[Federal Register Volume 67, Number 135 (Monday, July 15, 2002)]
[Notices]
[Pages 46464-46488]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-17637]


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DEPARTMENT OF ENERGY

Office of Energy Efficiency and Renewable Energy

[Docket No. EE-DET-02-001]


Building Energy Standards Program: Determination Regarding Energy 
Efficiency Improvements in the Energy Standard for Buildings, Except 
Low-Rise Residential Buildings, ASHRAE/IESNA Standard 90.1-1999.

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of 
Energy (DOE).

ACTION: Notice.

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SUMMARY: The Department of Energy (DOE or Department) today determines 
that the 1999 edition of the Energy Standard for Buildings, Except Low-
Rise Residential Buildings, American Society of Heating, Refrigerating 
and Air-Conditioning Engineers (ASHRAE) Illuminating Engineering 
Society of North America (IESNA) Standard 90.1-1999, (Standard 90.1-
1999 or the 1999 edition) would achieve greater energy efficiency in 
buildings, except low-rise residential buildings, than the 1989 edition 
(Standard 90.1-1989 or the 1989 edition). As a result of this positive 
determination regarding Standard 90.1-1999, each State is required to 
certify that it has reviewed and updated the provisions of its 
commercial building code regarding energy efficiency to meet or exceed 
Standard 90.1-1999 for any ``building'' within the meaning of Section 
303(2) of the Energy Conservation and Production Act, as amended. This 
Notice provides guidance to States on Certifications, and Requests for 
Extensions of Deadlines for Certification Statements.

DATES: Certifications and Requests for Extensions of Deadlines, with 
regard to Standard 90.1-1999, are due at DOE on or before July 15, 
2004.

ADDRESSES: Certifications, or Requests for Extensions of Deadlines 
should be directed to the Assistant Secretary for Energy Efficiency and 
Renewable Energy, Office of Building Technology Assistance, EE-42, 1000 
Independence Avenue, SW., Washington, DC. 20585-0121. Envelopes or 
packages should be labeled, ``State Certification of Commercial 
Building Codes Regarding Energy Efficiency.''

FOR FURTHER INFORMATION CONTACT: Jean J. Boulin, U.S. Department of 
Energy, Office of Energy Efficiency and Renewable Energy, Forrestal 
Building, Mail Station EE-2K, 1000 Independence Avenue, SW., 
Washington, DC 20585-0121, Phone: 202-586-9870, FAX: 202-586-1233.

SUPPLEMENTARY INFORMATION:

I. Introduction
    A. Statutory Requirements
    B. Background
    1. Publication of Standard 90.1-1999
    2. Workshop and Comments on Analysis Methodology
    3. Comments on Preliminary Quantitative and Textual Analyses
    C. Summary of the Comparative Analysis
    1. Quantitative Analysis
    2. Detailed Textual Analysis
    D. Determination Statement
II. Results of Quantitative Analysis
III. Discussion of Detailed Textual Analysis
    A. Lighting and Power
    1. Interior Lighting Power Exemptions
    2. Exterior Lighting Power
    3. Lighting Controls--Interior
    4. Ballast Efficacy Factor
    5. Exit Signs
    6. Interior Lighting Power--Whole Building
    7. Interior Lighting Power--Space-By-Space
    8. End Use Metering
    9. Transformers
    10. Motors
    B. Building Envelope
    1. Air Leakage
    2. Insulation Installation
    3. Allowance for Speculative Buildings
    4. Envelope Thermal Transmittance in Cold Climates
    5. Skylight Thermal Transmittance and Solar Heat Gain
    6. Slab-On-Grade and Below Grade Wall Insulation
    7. Roof Thermal Transmittance
    8. Floors Over Unconditioned Spaces
    9. Opaque Wall Thermal Transmittance
    10. Window Thermal Transmittance and Solar Heat Gain
    11. Opaque Doors
    C. Mechanical Equipment and Systems
    1. Load Calculations and Sizing
    2. Separate air distribution systems
    3. Temperature Controls
    4. Off-Hour Controls and Setback
    5. Dampers
    6. Humidity Control
    7. Radiant Heating
    8. Ventilation
    9. Pipe and Duct Insulation
    10. Heat Recovery
    11. Completion Requirements
    12. Simultaneous Heating and Cooling Controls
    13. Economizer Controls
    14. Fan System Design Criteria
    15. Pumping System Design
    16. Temperature Reset Controls
    17. Hot Gas Bypass Restriction
    18. Heating Ventilation and Air-Conditioning Equipment
    19. Service Water Heating Equipment Efficiency

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    20. Service Water Heating Controls
    D. Energy Cost Budget
    E. Conclusion About Detailed Textual Analysis
IV. Filing Certification Statements with DOE
    A. Review and Update
    B. Certification
    C. Request for Extensions
    D. Submittals

Appendix A. Description of Proposed Analysis

Appendix B. Description of the Quantitative Analysis

I. Analysis Methodology
II. Simulation Input Characterization
    A. Envelope
    B. Lighting
    1. Lighting Power--1989 Edition
    2. Lighting Power--1999 Edition
    C. Mechanical Equipment
    1. Cooling Equipment
    2. Space Heating Equipment
    3. Economizers
    4. Service Water Heating Equipment
    D. Aggregation of Results

I. Introduction

A. Statutory Requirements

    Title III of the Energy Conservation and Production Act (ECPA), 
establishes requirements for the Building Energy Efficiency Standards 
Program (42 U.S.C. 6831-6837).
    ECPA provides that whenever the Standard 90.1-1989, or any 
successor to that code, is revised, the Secretary must make a 
determination, not later than 12 months after such revision, whether 
the revised code would improve energy efficiency in commercial 
buildings and must publish notice of such determination in the Federal 
Register (42 U.S.C. 6833 (b)(2)(A)). The Secretary may determine that 
the revision of Standard 90.1-1989, or any successor thereof, improves 
the level of energy efficiency in commercial buildings. If the 
Secretary makes a determination that the revised standard will improve 
energy efficiency in commercial buildings, then not later than two 
years after the date of the publication of such affirmative 
determination, each State is required to certify that it has reviewed 
and updated the provisions of its commercial building code regarding 
energy efficiency with respect to the revised or successor code for any 
``building'' within the meaning of Section 303(2) of ECPA. The State 
must include in its certification a demonstration that the provisions 
of its commercial building code, regarding energy efficiency, meet or 
exceed the revised standard (in this case, Standard 90.1-1999) (42 
U.S.C. 6833(b)(2)(B)(i)). If the Secretary makes a determination that 
the revised standard will not improve energy efficiency in commercial 
buildings, State commercial codes shall meet or exceed Standard 90.1-
1989 or the last revised standard for which the Secretary has made a 
positive determination (42 U.S.C. 6833(b)(2)(B)(ii)).
    ECPA also requires the Secretary to permit extensions of the 
deadlines for the State certification if a state can demonstrate that 
it has made a good faith effort to comply with the requirements of 
Section 304(b) and that it has made significant progress in doing so 
(42 U.S.C. 6833(c)).

B. Background

1. Publication of Standard 90.1-1999
    The American Society of Heating, Refrigerating and Air-Conditioning 
Engineers (ASHRAE) and the Illuminating Engineering Society of North 
America (IESNA) approved the publication of the 1999 edition of Energy 
Standard for Buildings Except Low-rise Residential Buildings, in June 
1999. Several appeals to this decision were heard and subsequently 
rejected and the 1999 edition was published in February 2000.
    The Standard was developed under American National Standards 
Institute approved consensus standard procedures. The American Society 
of Heating Refrigerating and Air-Conditioning Engineers submitted the 
standard to the American National Standards Institute (ANSI) for 
designation as an approved ANSI standard. In December 2000, after 
several appeals by the American Gas Association, the 1999 edition of 
Standard 90.1 was approved as an American National Standard.
2. Workshop and Comments on Analysis Methodology
    In arriving at a determination, the Department first reviewed all 
significant changes between the 1989 edition and the 1999 edition of 
Standard 90.1. Standard 90.1 is complex and covers a broad spectrum of 
the energy related components and systems in buildings ranging from 
simple storage buildings to complex hospitals and laboratories. The 
size of buildings addressed range from those smaller than single family 
homes to the largest buildings in the world. The approach to 
development of the standard changed from that used for the 1989 
edition, as did the scope and the way components were defined. We 
concluded that a simple comparison of the two editions would not be 
possible. Therefore, we decided to hold a public workshop and seek 
public comment on our proposed analysis methodology. On February 8, 
2000, we proposed a methodology, announced a public workshop, and 
sought public comment. 65 FR 6195. On February 17, 2000, we held a 
workshop to obtain comment on the approach we proposed to use. See the 
summary of the proposed approach in Appendix A.
    We requested comments and/or data concerning issues relating to the 
comparative analysis of Standard 90.1-1989 and Standard 90.1-1999. We 
especially expressed interest in any comments or data regarding: (1) 
The seven building types selected for analysis; (2) the 11 
representative climate locations proposed for the analysis; (3) the 
frequency of use of alternative paths to compliance in building 
standards (e.g., space-by-space versus whole building lighting power 
allowances); (4) new non-residential building construction data by 
state or census division and building type; (5) data to quantify the 
impact of Standard 90.1-1999 on additions and renovations to existing 
buildings; (6) the prevalence of the semi-heated building envelope 
subcategory in the building types proposed for analysis; and (7) 
specific comments on the preliminary energy savings analysis 
distributed in June 1999.
    We received comments from American Electric Power, the American Gas 
Association, the Edison Electric Institute, GARD Analytics, Inc., the 
New Buildings Institute, and Virginia Power.
    American Electric Power, the Edison Electric Institute, and 
Virginia Power recognized that, given the numerous assumptions required 
to simulate the potential impact of the new standard, reasonable minds 
could differ over both the specific model employed and over the 
assumptions used in those models. For that reason, they cautioned the 
Department against becoming involved in a lengthy process aimed at 
reconciling all approaches. They expressed belief in the results of the 
initial analysis that the 1999 edition would save energy across a broad 
section of commercial buildings. We recognized their cautions about the 
complexity of the problem and magnitude of alternative compliance 
approaches in the standard. However, we felt obligated to extend the 
analysis as far as feasible.
    The New Buildings Institute supported the proposed methodology for 
the purpose of a simple yes/no determination but felt that the proposed 
methodology was inadequate for determining energy savings estimates 
associated with using Standard 90.1-1999. Here too, we recognized the 
difficulty of absolute quantification of savings, and make no such 
claim for the

[[Page 46466]]

analysis on which this determination relies.
    The American Gas Association argued that the Department should rely 
solely on quantitative estimates of energy savings as a means of 
comparing the two editions of Standard 90.1 and minimize the use of 
qualitative comparisons. We tend to agree with the previous comments 
from American Electric Power, the Edison Electric Institute, and 
Virginia Power, and the New Buildings Institute regarding the details 
of the analysis, and concluded that it was necessary to note changes 
that individually, or in net, result in increased energy efficiency, 
even where they could not be accurately quantified. We believe that 
States can use this information when upgrading their energy codes.
    The American Gas Association also expressed a strong belief that 
the analysis should be based on the minimum requirements of each 
edition and not on typical design and construction practice. In the 
area of heating, ventilating and air-conditioning and water heating 
equipment, the American Gas Association expressed the opinion that the 
Department should include analysis of equipment market share impacts in 
its analysis. It also expressed the opinion that the analysis be based 
on consensus forecasts of commercial construction activity, rather than 
on existing building stock, and use these forecasts as the basis for 
energy consumption calculations. It was concerned that the Department 
select the correct version of the 1989 edition for the baseline and 
recommended that the baseline be the 1989 edition plus all addenda to 
that edition, up to the publication of the 1999 edition. Finally, the 
American Gas Association expressed the belief that the analysis must 
include a cost-effectiveness and economic justification review.
    We agree that the analysis should be based on the minimum 
requirements of each standard but in assessing the impact of those 
requirements, we believe that assessment should be based on a realistic 
estimate of what is being built. We believe that we have done this in 
our analysis.
    We do not believe it is necessary for the Department to perform a 
quantitative analysis of the likely effects of Standard 90.1-1999 on 
fuel and equipment market shares in order to support a conclusion 
regarding the likely net energy savings that would result. Without 
performing a quantitative analysis of the possible effects on fuel or 
equipment market shares, there are several reasons why the Department 
has concluded that these effects are likely to be insignificant. First, 
since Standard 90.1-1999 places the same requirements on buildings with 
different types of heating or cooling equipment (and this was also true 
of previous ASHRAE standards), the impacts of the standard on most 
building costs should be identical, regardless of the type of energy or 
equipment used. Second, if the comparative costs and market shares of 
equipment used in buildings covered by the ASHRAE standard are 
influenced by other administrative actions taken by the Department of 
Energy or other government agencies, any effects on fuel market shares 
that result from such other actions cannot properly be attributed to 
the ASHRAE standard that is the subject of today's determination. 
Finally the choice of fuels and equipment by new building designers, 
builders, and owners is affected by many factors, only a few of which 
are related to the comparative first costs of the equipment and 
building systems involved. In cases where comparative equipment and 
system costs are a significant factor in fuel choice, the small changes 
in these costs that might be attributable to the ASHRAE 90.1-1999 
building standard are very unlikely to significantly affect market 
shares or the resulting energy savings.
    We considered using what the American Gas Association referred to 
as consensus forecasts of commercial construction activity, rather than 
data on the existing building stock in our analyses. We concluded, 
however, that available forecasts are not really consensus forecasts. 
These latter forecasts are extremely short term in perspective, and 
reflect that the construction market is likely to remain volatile over 
the intermediate term. We have therefore used the new construction 
square footage data from 2001-2010, extracted from the Energy 
Information Administration's National Energy Modeling System, as the 
basis for our analysis.
    Furthermore, AGA believes that each addendum should be treated as a 
revision to the standard, thus requiring DOE to issue a determination 
for each addendum pursuant to Section 304(b)(2) of ECPA, as amended, 42 
U.S.C. 6834 (b)(2). AGA has also questioned the appropriateness of the 
baseline DOE used when comparing the revised ASHRAE Standard 90.1-1999 
with its predecessor, ASHRAE Standard 90.1-1989, in order to determine 
whether the new ASHRAE Standard improves energy efficiency. AGA would 
have DOE use ASHRAE Standard 90.1-1989 with all of the addenda up until 
the publication of ASHRAE 90.1-1999 for the comparison.
    Section 304(b)(2) of ECPA, as amended, which applies to commercial 
building code updates, requires that when the provisions of ASHRAE 
Standard 90.1-1989, or any successor standard, are revised, the 
Secretary shall, not later than 12 months after the date of such 
revision, publish a notice in the Federal Register, with its 
determination as to whether the revised standard will improve energy 
efficiency in commercial buildings. Once the Secretary issues a 
determination, States have two years, with possible extensions for good 
faith efforts, to comply with the certification requirements in Section 
304(b)(2).
    DOE interprets the language in Section 304(b)(2) to mean that when 
a comprehensive revision of the ASHRAE Standard is published, which in 
this case is ASHRAE Standard 90.1-1999, then that revised or successor 
standard triggers the Secretary's obligation to issue a determination 
as to whether the revised standard improves energy efficiency. This 
determination is made by comparing the revised or successor standard to 
the last predecessor standard.
    While it is true that the addenda process is part of the ongoing 
maintenance of the standard and thus continually modifies the existing 
standard over time, it would be an unreasonable reading of the statute 
to categorize each addendum in this maintenance process as a ``revised 
or successor standard'' within the meaning of Section 304(b)(2), so as 
to require a determination by the Secretary. Such an interpretation of 
the statute would put an unreasonable burden both on the States and 
DOE. For the States, a determination by the Secretary requires some 
State action, and what is required depends upon whether the Secretary 
issues an affirmative or a negative determination. If the Secretary 
were required to issue a determination after each addendum was 
published, the States would be constantly required to change their 
codes. This would affect the stability and certainty of State 
commercial building codes. DOE believes that Congress could not have 
intended this result. Therefore, DOE concludes that the statute only 
requires a determination by the Secretary when there is a comprehensive 
revision to the standard.
    With respect to the baseline for comparing the energy efficiency of 
revised ASHRAE Standard 90.1-1999 with its predecessor, ASHRAE Standard 
90.1-1989, DOE's position is that the appropriate baseline is ASHRAE

[[Page 46467]]

Standard 90.1-1989 with addenda in effect at the time EPACT was 
enacted. Since this is the first determination for commercial building 
codes since ECPA was amended by EPACT on October 24, 1992, it is 
reasonable to interpret section 304(b)'s reference to ASHRAE Standard 
90.1-1989 to include the addenda in effect on the date of enactment. 
DOE interprets the statute to require a comparison of that version of 
ASHRAE 90.1-1989 (and not any subsequent addenda) with ASHRAE Standard 
90.1-1999. If DOE were to adopt the AGA position and include all of the 
intervening addenda to ASHRAE Standard 90.1-1989 up to the adoption of 
ASHRAE 90.1-1999 in the baseline, it would render DOE's determination 
almost meaningless. That is, if all of the post-enactment addenda to 
ASHRAE Standard 90.1-1989 were included in the baseline, the real 
energy efficiency improvements (assuming there are any) of the revised 
standard would be reflected in the baseline. A comparison of a revised 
standard and the previous standard (under such an interpretation) would 
always show little, if any, energy efficiency gains. That would defeat 
the statute's purpose of requiring DOE to compare the energy efficiency 
of revised standards (i.e., comprehensive revisions of ASHRAE Standard 
90.1-1989 or successor standards) with the prior or last standard.
    AGA and the Natural Resources Defense Council argue that DOE has a 
statutory responsibility to determine whether the revised standard 
would improve energy efficiency in commercial buildings and also 
whether all new energy efficiency measures are technologically feasible 
and economically justified. (Letter dated April 12, 2000, from the 
American Gas Association and the Natural Resources Defense Council, 
signed by Charles H. Fritts and Katherine Kennedy, to Dan W. Reicher, 
Assistant Secretary Energy Efficiency and Renewable Energy) They 
contend that DOE is required to conduct cost-effectiveness and economic 
justification analyses as part of the process in making its 
determination concerning ASHRAE Standard 90.1-1999 pursuant to Section 
304 of ECPA, as amended. These who commented believe that the statutory 
scheme, including Section 307, entitled ``Support for Voluntary 
Building Energy Codes,'' supports its argument.
    The statutory language in Section 304(b) states that the Secretary 
is required to make a determination as to whether any successor 
standard to ASHRAE Standard 90.1-1989 will improve energy efficiency. 
The Secretary must publish a notice of this determination in the 
Federal Register. The language does not require that DOE perform an 
independent economic analysis as part of the determination process. As 
a matter of fact, Section 304(b) omits any reference to language 
concerning economic justification.
    However, Congress was concerned that the technological feasibility 
and cost effectiveness of the Voluntary Building Energy Codes be 
considered. Section 307 clearly requires DOE to participate in the 
ASHRAE process and to assist in determining the cost effectiveness and 
technical feasibility of the ASHRAE standard. It also requires DOE to 
periodically review the economic basis of the voluntary building energy 
codes and participate in the industry process for review and 
modification, including seeking adoption of all technologically 
feasible and economically justified energy efficiency measures.
    Unlike Section 307 which specifically includes language concerning 
economic justification, Section 304 omits any reference to economic 
justification. It is generally presumed that Congress acts 
intentionally and purposefully where it includes particular language in 
one section of a statute but omits it in another section. See Bates v. 
United States, 522 U.S. 23, 29-30 (1997). Accordingly, the statutory 
scheme cannot be read to require an economic analysis as part of the 
determination process in Section 304(b).
    The fact that the Section 304 determination process does not 
require the Secretary to perform an economic analysis does not diminish 
the importance that the ASHRAE standards be technologically feasible 
and economically justified. However, it appears that Congress assumed 
that these concerns would be worked out by stakeholders, with DOE 
participating in the ASHRAE process itself. The language of Section 307 
clearly delineates DOE as one participant in the process, not the 
ultimate decision maker of the ASHRAE standard or successor revisions.
    Accordingly, for all of these reasons, DOE has determined that it 
is not required to perform an economic analysis as part of its 
determination process in Section 304 of ECPA, as amended.
    A number of the GARD Analytics comments were incorporated into our 
analysis. They include: (1) Extending the aggregation to cover 
buildings with different window area fractions instead of doing a 
sensitivity analysis; (2) use of the Alternate Component Packages 
tables in the 1989 edition's envelope section, to make it easier to 
identify the criteria which should be used in modeling the 1989 
edition's envelope criteria; and (3) eliminating estimates of equipment 
operating hours in weighting equipment efficiency. In addition, we 
estimated efficiency improvement for cooling equipment and incorporated 
estimates of both single and three phase unitary cooling equipment less 
than 65,000 Btu per hour, shipped to commercial buildings.
    GARD Analytics suggested we use specific prototype buildings as it 
did in its analysis, instead of our scaling approach. It also urged us 
to select specific building sizes for analysis. We believe that by 
using a scaling approach, we can better assess the impact of building 
envelope changes. Scaling permits us to better account for the actual 
ratio of building wall area to floor area in a population of buildings, 
rather than assume some fraction of the building population has a 
single size and geometry and that those characteristics hold for all 
buildings in that fraction of the building population. The size 
selection of the prototype used for scaling is near the median square 
footage for most building categories. Using a building size that is 
close to the median helps ensure that the characterization of secondary 
effects, such as the transitional performance of the building under 
thermostat setback conditions, is captured in a manner that is 
reasonable for the majority of the building population.
    GARD Analytics also commented on our use of a one-to-one aspect 
ratio (the ratio of length to width of a building) in the prototype. 
While we use an aspect ratio of one-to-one in the prototype simulation, 
to make the simulation orientation neutral, our scaling process does 
include typical aspect ratios for all building types to correctly 
determine the ratio of perimeter and core areas in the building 
population. GARD Analytics commented that the use of scaling does not 
allow the use of different lighting power densities for different 
building sizes, as are shown in the 1989 edition. In our approach the 
weighted average lighting power density over all Commercial Building 
Energy Consumption Survey building sizes was used as the basis of our 
simulation of the 1989 edition's requirements. This correctly 
characterizes the average lighting improvement over all building sizes.
    GARD Analytics also had a number of comments on our proposed 
methodology. It suggested that selection of building types by baseline 
energy use was less correct than if it was done by square footage. We 
disagree. The purpose of selection by energy use, as

[[Page 46468]]

opposed to square footage, is to select the building types that will be 
most significant in terms of national energy use. We believe that as 
the number of building types used is increased, the set of buildings 
types selected by either method will converge to the same set.
    GARD Analytics also questioned elimination of the in-patient health 
care facilities category from our analysis and stated that available 
hospital models could be used. In-patient health care facilities are 
perceived to have high thermal loads and equipment loads within the 
health care category. Given the requirements of the 1999 edition, 
inclusion of this category would increase estimates of energy savings. 
However, we considered the relatively low ranking of in-patient health 
care buildings in terms of net energy use and the modest level of 
future in-patient health care new building growth. This reduced the 
importance of modeling this category. Finally, we did not have 
confidence in the representative nature of available in-patient 
healthcare models. We therefore chose not to simulate this building 
type separately in our analysis. We believe that not doing so resulted 
in a conservative estimate of the energy savings attributable to the 
1999 edition.
    GARD Analytics also commented that we should use the operating 
schedules and loads from the 1999 edition for the analysis. Our 
selected schedules are based on accurate measured data and we believe 
that they are at least as representative of typical buildings as those 
in the 1999 edition.
    GARD Analytics commented on the use of supplemental lighting power 
allowances. We concluded that the most appropriate lighting power 
allowances for our quantitative comparison were the whole-building 
lighting requirements. We commented on the space-by-space requirements 
and the impact of the supplemental lighting power allowances in our 
detailed textual analysis.
    GARD Analytics commented that we should use the maximum fan power 
allowances under both standards in our comparison. However, since the 
maximum fan power allowances are effectively the same in both 
standards, and are not believed representative of typical building 
design, we chose to use a more typical fan power usage and thus show a 
more realistic level of energy usage for buildings under both 
standards. Utilizing the maximum fan power would increase internal 
building loads, decrease heating loads and lower building balance 
temperature. The impact would be to increase absolute energy savings 
over the 1989 edition.
    DOE2.1 and BLAST (Building Loads and System Thermodynamics) are 
both building energy analysis computer programs. GARD Analytics 
commented that DOE should use DOE2.1, instead of BLAST, as the basis of 
the energy simulations. They state that DOE2.1 is more commonly used by 
building designers and that further development of BLAST is being 
phased out. DOE disagrees with the comment since BLAST forms the basis 
of the Department's new, improved simulation tool, Energy Plus, and 
since DOE is actually phasing out support for DOE2.1.
    GARD Analytics commented that we should use the most stringent 
compliance path on which to do our quantitative analysis. The 
Department considered this but selected the prescriptive compliance 
paths on which to base its quantitative analysis, since it is those 
paths for which specific requirements can be accurately identified for 
``prototype'' buildings. Selecting representative requirements from the 
variable requirements in the other paths becomes highly speculative. We 
have addressed requirements from these other compliance paths in the 
detailed textual analysis.
    GARD Analytics commented on the selection of climates and regional 
weighting for our analysis. It felt that DOE's strategy to select the 
cities (which represent sets of climate data) is suboptimal and ignores 
the real effect of the standard having different criteria in different 
climates. We have reviewed our selection of climates and methodology 
and believe it to be entirely representative and appropriate for this 
analysis. GARD Analytics also commented that it was unnecessary to use 
sub-census regions in our aggregation approach. However, we feel that 
the use of sub-census regions is necessary to correctly represent the 
variation in energy costs in the western U.S. We believe that it 
introduces no additional error in the remainder of the analysis.
    GARD Analytics made a number of comments that we should do more 
detailed analyses. Examples of further analysis suggested by GARD 
Analytics included: state by state comparisons of the standards, the 
development of lighting power usage using the space-by-space method, 
inclusion of room air conditioners in the development of the cooling 
equipment efficiencies, the use of below ground building spaces in the 
comparison, and the use of marginal energy costs. We reviewed these 
comments, but concluded that the limited data available for describing 
building populations and weighting the results of more simulations 
would not result in a more accurate conclusion to our analysis. A 
number of these comments are addressed in our detailed textual 
analysis.
3. Comments on Preliminary Quantitative and Textual Analyses
    As a matter of policy to further the determination process, we 
sought further comments on the application of the methodology and the 
validity of preliminary conclusions posted on our web site. A summary 
of comments and responses on common topical issues, regarding the 
application of the methodology and the preliminary conclusions, follows 
below. For detailed responses to the comments received, see Response to 
Comments on Preliminary Analyses Supporting DOE's Determination 
Regarding Standard 90.1-1999, which is part of the administrative 
record for this Determination Notice. This document may be viewed at 
the DOE Freedom of Information Reading Room, U.S. Department of Energy, 
Forrestal Building, Room 1E-190, 1000 Independence Avenue S.W., 
Washington, D.C. 20585, (202) 586-3142, between the hours of 9:00 a.m. 
and 4:00 p.m., except Federal holidays, or a copy may be obtained from 
the Department from the contact person identified above.
    We received 12 comments, two from design practitioners (G. Johnson 
and Kay), four from States or code officials (Lloyd, Weitz, Cowen, 
Hogan), one representing States in a region (Coakley), one jointly from 
the two professional societies sponsoring the consensus process that 
developed the Standard (Wolf and Timmings), one from a public interest 
group (Goldstein), one from an energy code consultant (J. Johnson), and 
two representing the gas industry (Ranfone and Hemphill). Two who 
commented (Johnson and Kay) did not comment on the analysis. One of 
those who did not comment on the analysis joined four others who 
commented that the Department was late in making its determination and 
that the delay was hampering the Region's or State's updating of its 
energy codes (G. Johnson, Lloyd, Coakley, and Weitz). Of the nine 
commenting on the analysis, seven felt the analysis was well done or 
reasonable and agreed with the results. (Lloyd, Cowen, Coakley, Weitz, 
Wolf and Timmings, Goldstein and J. Johnson). One who commented 
suggested a change and wanted some further analysis done (Hogan), and 
another who commented had 35 detailed comments (Hemphill).

[[Page 46469]]

    Five complained about the amount of time it is taking the 
Department to make a determination (Johnson, Cowen, Coakley, Weitz, and 
Goldstein). They stated that the delay was adversely impacting States 
ability to update their energy codes and gain energy and greenhouse gas 
benefits.
    Five commented that they interpreted the analyses to conclude that 
there would be a net positive increase in commercial building energy 
efficiency and agreed with the conclusion for a positive determination. 
(Coakley, Lloyd, Weitz, Wolf and Timmings, Goldstein, and J. Johnson). 
Three of these further commented that the analyses were reasonable. One 
(Weitz) expressed the opinion that this is an achievable standard and 
indicated that Massachusetts has already adopted a new construction 
energy code based on the 1999 edition. However, one (Ranfone) commented 
that DOE should not complete its determination, until such time as an 
analysis is done to determine whether all new energy efficiency 
measures are technologically feasible and economically justified, a 
comment DOE previously addressed above.
    One (Hogan) commented, and we agree, that the building envelope 
criteria for the ``lodging'' category in our quantitative analysis 
should be taken from the ``residential'' column in the tables in 
Appendix B of the 1999 edition, rather than from the ``nonresidential'' 
category, since the only change was in the opaque envelope. We have 
revised the analysis accordingly.
    Hogan also commented that the quantitative analysis should be 
expanded to include all energy used in buildings, including elevators, 
exterior lighting for entrances and facades, parking lighting, and 
parking ventilation, and be expanded to differentiate part-load 
operation between fan systems with and without variable frequency fans. 
Data on buildings and building component characteristics are 
insufficient to accurately include these in our analysis. However, each 
is addressed in the detailed textual analysis, except for elevators 
which are not addressed in either the 1989 or 1999 editions of Standard 
90.1.
    One who commented (Hemphill) submitted 35 detailed comments on our 
analyses. We agreed in whole or in some part with eleven of these 
comments and have accordingly made changes or clarifications to our 
textual analysis. These eleven include comments on: exterior lighting 
power, interior lighting power--space-by-space, envelope air leakage, 
floors over unconditioned spaces, opaque wall thermal transmittance, 
opaque doors, load calculations and sizing, off-hour controls and 
setbacks, simultaneous heating and cooling controls, air-conditioning 
equipment, and non-code language. In several cases, while we disagreed 
with comments, we further clarified our rationale, as noted below.
    Six comments received had to do with differing interpretations of 
the standard. These included comments having to do with lighting power 
exemptions, lighting integral to equipment, transformers, 
transportation systems, energy management systems, and the energy cost 
budget compliance path. On review, we disagreed with the 
interpretations presented in the comment and made no change. For 
example, in the case of energy management systems, they are recommended 
not required, as implied in the comment, in buildings over 40,000 
square feet in the 1989 edition. In the 1999 edition, energy management 
systems are not omitted but are addressed differently, under controls. 
In the case of the comment on the energy cost budget compliance path, 
we believe that both editions establish a baseline of requirements from 
the prescriptive compliance approach and require the energy cost of the 
design to be equivalent or less than the baseline. We therefore believe 
that in each edition the energy cost budget compliance path criteria 
are roughly equivalent to the prescriptive compliance path.
    The comments of Hemphill, which related to transformers, 
transportation systems, and energy management systems, suggested that 
we might have missed some differences between the two editions of the 
standard. On inspection we found that we had missed some differences. 
Therefore we have added analysis that addresses the subdivision of 
electric power feeders and provisions for check metering of loads.
    Eight comments received had to do with differing opinions on 
appropriate approaches to the textual analysis. These included comments 
on the subjective nature of the analysis of the envelope section, exit 
signs, the use of the prescriptive compliance path and not the 
performance paths in the analysis, our conclusions on the lighting 
power exemptions, window thermal transmittance and solar heat gain, 
temperature reset controls, and heating equipment. Four of these 
comments provide no suggestion of an alternative approach. We believe 
that our approach in the textual analysis provides useful information 
to states which will adopt the standard, even if the changes cannot be 
fully quantified. In the case of exit signs, and heating equipment, we 
did not agree that, where there were no criteria in the 1989 edition 
and there were criteria in the 1999 edition, we could not or should not 
project savings. No changes were made in response to these comments 
except for the comment on window thermal transmittance, where 
explanatory text was added to the textual analysis.
    Six other comments were received with which we disagreed but which 
led us to adding explanatory text to the textual analysis. This was 
done in the analysis relative to speculative building envelopes, 
envelope thermal transmittance in cold climates, slab on grade and 
below grade wall insulation, roof thermal transmittance, temperature 
controls, and pipe and duct insulation. One of these, the comment on 
pipe and duct insulation appeared to be a misinterpretation of what we 
wrote. In addition, more analysis was done on the subject of roof 
thermal transmittance.
    Five comments appear to have been a misinterpretation of our 
written analysis. These comments concerned parts of our whole building 
interior lighting power criteria, interior lighting controls and 
separate air distribution systems, radiant heating, and service water 
heating equipment. In the case of the comment on interior lighting 
controls, there are also opinions stated without support. Review of our 
explanations did not suggest any change.
    One (Hemphill) argued that there was no difference in scope between 
the two editions. However, four others (Coakley, Weitz, Wolf and 
Timmings, and Goldstein) all recognized the expansion of the scope of 
the 1999 edition to renovations of existing buildings. We agree with 
the latter majority opinion including those representing the 
organizations sponsoring the two editions. We note that through the mid 
1990s the American National Standards Institute recognized the ASHRAE 
Standard 100 series, that explicitly addressed existing buildings. 
Under American National Standards Institute policy, two standards 
(Standard 90.1-1989 and ASHRAE Standard 100) could not address existing 
buildings.
    One (Hemphill) interpreted our analysis regarding increasing the 
scope of the 1999 edition to existing buildings to imply that the 
increased energy efficiency could approach 50 percent of the energy use 
reduction from new construction and expressed the opinion that there 
was absolutely no basis for this assertion, and that the implication 
was wholly inappropriate. Another

[[Page 46470]]

(Wolf and Timmings) commented on the subject that industry estimates 
indicate that at least 60 percent of heating and cooling equipment 
sales are for replacement markets, and only 40 percent for new 
buildings, but did not provide a source for this estimate. We continue 
to believe that it is difficult to quantify the energy efficiency 
impact of the change in scope to include existing buildings. We will 
not attempt to estimate the impact of this change. Today's 
determination does not address or rely on this difference.

C. Summary of the Comparative Analysis

    We carried out both a broad quantitative analysis and a detailed 
textual analysis of the differences between the requirements and the 
stringencies in the 1989 and the 1999 editions.
1. Quantitative Analysis
    The quantitative comparison of energy codes was done using whole-
building energy simulations of buildings built to each standard. We 
simulated seven representative building types in 11 representative U.S. 
climates. Only differences between new building requirements were 
considered in this quantitative analysis. The simulations were based on 
a 15 zone building prototype used in previous DOE building research. 
The simulated Energy Use Intensities (EUI) for each zone were scaled to 
correctly reflect variations in building size and shapes for each 
representative building type. Energy use intensities developed for each 
representative building type were weighted by total national square 
footage of each representative building type to provide an estimate of 
the difference between the national energy use in buildings constructed 
to both editions. A more detailed explanation is located in Appendix B 
to this notice.
    The quantitative analysis of the energy consumption of buildings 
built to the 1999 edition, compared with buildings built to the 1989 
edition for new buildings, indicates national source energy savings of 
approximately 6.4 percent of commercial building energy consumption. 
Site energy savings are estimated to be approximately 4.5 percent. 
These figures represent a conservative estimate of energy savings for 
new buildings.
2. Detailed Textual Analysis
    We also performed a detailed analysis of the differences between 
the textual requirements and stringencies of the two editions of 
Standard 90.1 concerning the scope of the standard, the building 
envelope requirements, the building lighting and power requirements, 
and the building mechanical equipment requirements. The detailed 
textual analysis addresses a number of differences that, while very 
real, we could not accurately or reliably quantify because of lack of 
reliable information about the building stock and the incorporation of 
various components and equipment in various parts of the country. 
Therefore, the detailed textual analysis makes no attempt to quantify 
the differences between the 1989 and 1999 editions.
    The emphasis of our detailed requirement and stringency analysis 
was on differences between the envelope, lighting, and mechanical 
sections of both editions of Standard 90.1.
    The lighting requirements comparison focused on the impact the 
different lighting requirements have on lighting energy use, as well as 
on building loads. The comparison looked separately at the whole 
building and space-by-space lighting requirements in both standards in 
a variety of commercial building types, as well as examined the effect 
of any ``additional lighting power allowances.'' It also looked at 
controls.
    The mechanical requirements comparison looked at equipment 
efficiency requirements and system design requirements. The system 
design requirements affect the system efficiency, system thermal load, 
and also had some direct energy impacts.
    In comparing the envelope requirements, we made judgements of 
relative stringency and frequency of occurrence of components.
    Each standard has multiple ways to demonstrate compliance. We did 
not perform a detailed comparison of the relative stringency of the 
alternate paths internal to a single standard or between standards. The 
large number of variables among the alternative compliance paths made 
such a comparison prohibitive to undertake. Further, we knew of no data 
on which to base the selection of representative requirements for such 
an analysis. Assignment of requirements would have been arbitrary. 
Rather we focused on the prescriptive compliance paths in each section, 
which we believe represent the most common approach to using the 
standard in question for most buildings.

D. Determination Statement

    The Department's review and evaluation found that there are 
significant differences between the 1989 edition and the 1999 edition. 
Our overall conclusion is that the 1999 edition will improve the energy 
efficiency of commercial buildings, even though in certain limited 
instances stringencies for some requirements are reduced. However, we 
found a number of changes in textual requirements and stringencies that 
will decrease energy efficiency. Overall, we concluded the changes in 
textual requirements and stringencies are ``positive,'' in the sense 
that they will improve energy efficiency in commercial construction. 
Our quantitative analysis shows, nationally, new building efficiency 
should improve by about six percent, looking at source energy, and by 
about four percent, when considering site energy. DOE has therefore 
concluded that the 1999 edition should receive an affirmative 
determination under Section 304(b) of the Energy Conservation and 
Production Act for ``buildings'' within the meaning of Section 303(2).

II. Results of Quantitative Analysis

    Tables 1 and 2 show the aggregated energy use and associated energy 
savings by building type for the seven categories analyzed and on an 
aggregated national basis for the 1989 and 1999 editions, respectively. 
See Appendix B for an explanation of the methodology we used. For each 
edition the building floor area weight is used to calculate the 
building energy or cost use intensity. The electric and gas building 
energy use intensity is presented for each type analyzed with electric 
predominating in all types. Site energy use intensities ranges from 
more than 137 thousand Btu per square foot annually for the Food 
building type to more than 18 thousand Btu per square foot annually for 
the Warehouse building type. Source energy use intensities have similar 
ranges as site energy ranges but vary in quantitative order from site 
energy intensities. (Lodging and Office rank 4th and 5th respectively 
for site energy, while for source energy their ranking is reversed, 5th 
and 4th respectively.). Building energy cost intensities are also 
presented.

[[Page 46471]]



                     Table 1.--Estimated Energy Use Intensity by Building Type--1989 Edition
----------------------------------------------------------------------------------------------------------------
                                      Building     Whole building energy use intensity  (kBtu/sf-yr or $/sf-yr)
           Building type             type floor ----------------------------------------------------------------
                                    area weight    Electric       Gas        Site EUI    Source EUI      $UI
----------------------------------------------------------------------------------------------------------------
Assembly..........................        0.068        61.55        32.18        93.73       231.78         1.48
Education.........................        0.218        35.65        18.86        54.50       134.47         0.87
Food..............................        0.027       101.60        35.52       137.12       363.04         2.32
Lodging...........................        0.079        42.80        17.61        60.41       155.88         1.00
Office............................        0.190        49.85         5.61        55.45       165.00         1.09
Retail............................        0.246        57.14         3.95        61.09       186.39         1.23
Warehouse.........................        0.173        10.43         8.19        18.62        42.32         0.27
National..........................  ...........        43.36        12.09        55.44       151.52         0.99
----------------------------------------------------------------------------------------------------------------


                     Table 2.--Estimated Energy Use Intensity by Building Type--1999 Edition
----------------------------------------------------------------------------------------------------------------
                                      Building     Whole building energy use intensity  (kBtu/sf-yr or $/sf-yr)
           Building type             type floor ----------------------------------------------------------------
                                    area weight    Electric       Gas        Site EUI    Source EUI      $UI
----------------------------------------------------------------------------------------------------------------
Assembly..........................        0.068        55.71        33.88        89.59       215.04         1.37
Education.........................        0.218        31.59        20.05        51.64       122.88         0.79
Food..............................        0.027       102.78        34.91       137.69       366.12         2.35
Lodging...........................        0.079        41.04        15.94        56.98       148.41         0.95
Office............................        0.190        44.56         6.32        50.88       148.95         0.98
Retail............................        0.246        48.14         5.17        53.31       159.08         1.05
Warehouse.........................        0.173        17.91         9.11        27.02        67.15         0.43
National..........................  ...........        40.04        12.91        52.95       141.88         0.92
----------------------------------------------------------------------------------------------------------------

    Table 3 presents the estimated percent energy savings between the 
1989 and 1999 editions. Overall, considering those differences that can 
be reasonably quantified, the 1999 edition will increase the energy 
efficiency of commercial buildings. However, this is not true for new 
buildings of all building types. In the case of the Food Service and 
the Warehouse building categories, the 1999 edition will allow 
increased energy usage. This is primarily due to an increased lighting 
power allowance for these building categories under the 1999 edition. 
Numbers in Table 3 represent percent energy savings. Thus, negative 
numbers represent increased energy use.

                 Table 3.--Estimated Percent Energy Savings With 1999 Edition--by Building Type
----------------------------------------------------------------------------------------------------------------
                                      Building       Percent reduction in whole building energy use intensity
           Building type             type floor ----------------------------------------------------------------
                                    area weight    Electric       Gas        Site EUI    Source EUI      $UI
----------------------------------------------------------------------------------------------------------------
Assembly..........................        0.068          9.5         -5.3          4.4          7.2          7.5
Education.........................        0.218         11.4         -6.3          5.2          8.6          9.0
Food..............................        0.027         -1.2          1.7         -0.4         -0.8         -0.9
Lodging...........................        0.079          4.1          9.5          5.7          4.8          4.7
Office............................        0.190         10.6        -12.7          8.2          9.7          9.8
Retail............................        0.246         15.7        -30.7         12.7         14.7         14.9
Warehouse.........................        0.173        -71.6        -11.3        -45.1        -58.7        -59.7
National..........................        1.000          7.6         -6.8          4.5          6.4          6.6
----------------------------------------------------------------------------------------------------------------

    A comparison of energy savings by building type for each of the 
different standard scenarios modeled is shown in Table 4, to give an 
idea of where most of the savings or increases derive. For example, we 
estimate a slight percentage increase in energy use intensity indicated 
in the ``1989 edition with 1999 edition envelope requirements'' row, 
indicated by the negative savings. Similarly there is an estimated 
percentage increase in gas energy use intensity indicated in the ``Gas 
EUI'' column, also indicated by negative savings. Conversely, other 
rows indicate estimated percentage reduction in energy use intensity 
for lighting and mechanical requirements.

                               Table 4.--Percent Energy Savings From 1989 Edition
                                     [National figures, all building types]
----------------------------------------------------------------------------------------------------------------
                                                   Electric
               Standard scenario                     EUI        Gas EUI      Site EUI    Source EUI      $UI
----------------------------------------------------------------------------------------------------------------
1989 edition...................................            0            0            0            0            0
1989 edition with 1999 edition envelope                 -0.1         -4.3         -0.9         -0.3         -0.3
 requirements..................................
1989 edition with 1999 edition lighting                  5.9         -8.3          2.8          4.6          4.9
 requirements..................................
1989 edition with 1999 edition lighting and              6.0        -10.1          2.5          4.6          4.8
 envelope requirements.........................

[[Page 46472]]

 
1989 edition with 1999 edition mechanical                2.2          3.0          2.4          2.3          2.2
 requirements..................................
1999 edition compliant buildings...............          7.6         -6.8          4.5          6.4          6.6
----------------------------------------------------------------------------------------------------------------

III. Discussion of Detailed Textual Analysis

    The 1999 edition is written in code language and as a result 
excludes some of the guidance provided in the 1989 edition. Although 
the guidance in the 1989 edition is not enforceable, it provided 
designers with suggestions for implementing energy efficient solutions. 
However, the guidance in the 1989 edition made it difficult for 
designers and code officials to quickly identify the relevant criteria.

A. Lighting and Power

1. Interior Lighting Power Exemptions
    The 1989 edition entirely exempts a number of lighting categories 
such as display or accent lighting for galleries, and lighting in 
spaces designed for the visually impaired. In doing so, it also exempts 
controls for those lights. While the 1999 edition exempts the lighting 
power requirements, it retains requirements for controls in the 
exempted areas. Lighting for outdoor manufacturing, commercial 
greenhouses, and process facilities; and special lighting for research 
are exempt in the 1989 edition but not in the 1999 edition. These 
differences can be expected to result in some reduction in lighting 
power use as a result of the additional coverage in the 1999 edition. 
Conversely, there are a number of narrowly targeted exemptions in the 
1999 edition that are not in the 1989 edition. These include: lighting 
integral to equipment installed by its manufacturer; lighting integral 
to open and glass enclosed refrigerator and freezer cases; lighting 
integral to food warming and preparation equipment; lighting in 
interior spaces that have been designated as a registered interior 
historic landmark; exit signs; lighting that is for sale or lighting 
educational demonstration systems; and casino gaming areas. The first 
three of these are not generally controlled by the 1989 edition because 
they are rarely known at the time the lighting plans are approved. 
While portions of gaming areas are often considered entertainment areas 
and exempt, the broader 1999 edition exemption can be expected to 
increase energy use in casinos. Lighting for landmark interiors might 
also increase in some cases. The net effect of these differences in 
exempted spaces is expected to be a small increase in efficiency in the 
1999 edition.
2. Exterior Lighting Power
    The 1989 edition prescribes maximum installed lighting power 
(Watts/square foot or Watts/ linear foot) for exterior building and 
grounds areas that, when added together, become the allowed exterior 
wattage. The 1999 edition sets similar criteria for exits, entrances 
and surface areas or facades, but also adds an efficacy requirement of 
60 lumens per Watt in luminaries of more than 100 Watts. There is a 
three Watts per lineal foot increase in allowable wattage for entrances 
without canopies in the 1999 edition. However, there is a decrease in 
allowable wattage for all exits (five Watts per lineal foot), and for 
high traffic canopied entrances (seven Watts per square foot), and for 
light traffic canopied entrances (one Watt per square foot). The net 
impact is unknown as data on the number of building entrances and exits 
and their characteristics are not known.
    For loading areas, loading doors, storage and non-manufacturing 
work areas, and driveways, walkways, and parking lots, the 1999 edition 
deviates from the 1989 edition by eliminating any Watts/square foot or 
Watts/linear foot maximums and instead sets an efficacy requirement of 
60 lumens per Watt (more than 100 Watts per luminaire). This 
requirement in the 1999 edition eliminates the use of low efficiency 
technologies, such as incandescent lamps, and allows the economics of 
fixture and energy cost to restrict the exterior lighting use to the 
minimum needed. We are aware of no data on which to make a judgement as 
to net decrease or increase in energy use from this change.
3. Lighting Controls--Interior
    The 1989 edition requires control points for each task or group of 
tasks within a 450 square foot area. It ``counts'' control ``points'' 
(one for manual, two for occupancy sensors, etc.) to show compliance 
with this requirement, giving credit to automatic controls versus 
manual ones. It further sets a minimum of one control for each 1,500 
Watts of lighting. In place of this task control requirement, the 1999 
edition requires all buildings more than 5,000 square feet in size to 
have automatic lighting shutoff in all spaces using time of day, 
occupancy sensor or similar methods. Buildings more than 5,000 square 
feet make up approximately half the number of commercial buildings 
built and more than 89 percent of the floor area constructed. This 
should save energy in these buildings during unoccupied hours. Where 
occupant sensors are used to comply with the requirement, the savings 
should be greatest, since this will shut off lights in unoccupied 
individual spaces, even during regular business hours.
    The 1999 edition adds control requirements for six specific 
lighting functions: all task lighting, hotel/motel guest rooms, 
display/accent lighting, case lighting, nonvisual (plant growth, food 
warming), and demonstration (for sale or for lighting demonstration). 
Furthermore, the 1999 edition requires that spaces up to 10,000 square 
feet in size have at least one control per 2,500 square feet and that 
larger spaces have one control per 10,000 square feet. In buildings 
with large open areas with multiple task areas lit by general lighting, 
the 1989 edition would require more (total manual or automatic) 
switching than the 1999 edition. The 1999 edition instead reduces 
lighting use in unoccupied spaces with automatic controls that do not 
require human intervention. The 1999 automatic control requirements are 
more likely to reduce lighting energy use in these spaces, than the 
manual controls permitted in the 1989 edition.
    The 1989 edition provides lighting control credits for use in 
calculating interior lighting power densities to encourage the use of 
automatic controls. For each area or group of lights that are 
controlled by an occupancy sensor, lumen maintenance sensor, daylight 
sensor, or combination of sensors, the design connected lighting power 
value, used in showing compliance, can be reduced from 10 percent to 40 
percent, depending on the controls used. This allows more lighting 
power to be used in the space in exchange for the use of an automatic 
lighting control. The 1999 edition requires the use of automatic

[[Page 46473]]

controls without allowing an increase in connected power.
    The 1989 edition requires permanently wired lighting fixtures and 
switched receptacles in hotel suites of rooms to be controlled at the 
entrance to each room. The 1999 edition further requires this control 
to be at the entrance of the entire suite area. The 1999 edition should 
save energy by making it easier to turn off all the lights on the way 
out.
4. Ballast Efficacy Factor
    The 1989 edition includes a minimum ballast efficacy factor. The 
1999 edition does not. However, new ballast manufacturing standards, 
required under the Energy Policy and Conservation Act, serve the same 
purpose and no longer make it necessary to include such criteria in the 
1999 edition. There will be no change in energy use as a result of this 
difference.
5. Exit Signs
    The 1999 edition includes an additional section specifying a 
minimum efficiency (35 lumens per Watt) for all exit signs operating at 
greater than 20 Watts that is intended to eliminate the use of standard 
incandescent lamps in exit signs. This will essentially eliminate the 
use of incandescent exit signs thereby reducing energy consumption.
6. Interior Lighting Power--Whole Building
    The 1999 edition provides greater clarity in specifying the 
calculation of luminaire or lighting system wattage that covers self 
ballasted, remote ballasted, track lighting systems and other 
miscellaneous lighting. This could eliminate some underestimation of 
installed lighting power. For example, it is common for a fluorescent 
lighting fixture to be described by builders (with respect to power 
consumption) as the simple sum of the lamp wattages while ignoring 
ballast energy use.
    The 1989 edition presents a set of whole building lighting power 
density requirements for 11 building types in six different building 
size ranges (0-2,000; 2,001-10,000; 10,001-25,000; 25,001-50,000; 
50,001-250,000; and greater than 250,001 square feet). The 1999 edition 
presents a single set of whole building lighting power density 
requirements for 31 building types without building size variation. For 
four of the building types, where there is a reasonable match between 
1989 and 1999 editions, the 1999 allowance is higher by 0.06 to 0.64 
Watts per square foot. Seven other matched building types show the 1989 
edition having lighting power allowances 0.20 to 0.80 Watts per square 
foot higher than in the 1999 edition. Considering all eleven matched 
building types, there is an average reduction of 0.11 Watts per square 
foot with the 1999 edition. Within the two building types representing 
the largest percentage of building floor area in the commercial sector 
(office and retail) the reductions with the 1999 edition are 0.40 Watts 
per square foot for office and 0.60 Watts per square foot for retail 
buildings. Because there is an average reduction of lighting power 
densities from the 1989 edition to the 1999 edition in all matching 
building types, and also a reduction in the lighting power densities 
allowed in the two largest building types (office and retail), the 
overall effect of the whole building lighting power density 
requirements in the 1999 edition will be to provide increased energy 
efficiency in most building types. However, it should be noted that 
there is an increase in the lighting power allowance for warehouse and 
storage type buildings which are significant in terms of total 
commercial building area. We expect a net reduction in energy use, with 
the whole building requirements. (See also the quantitative analysis of 
lighting requirements, Table 4.)
7. Interior Lighting Power--Space-By-Space
    Both the 1989 and 1999 editions present individual building space 
lighting power allowance values for use in applying a space-by-space 
compliance method where individual space lighting power is aggregated 
to arrive at a building total power allowance. The 1989 edition's 
tabulated space-by-space allowances are used in the compliance process 
only after they have been adjusted by an Area Factor (AF) ranging from 
1.0 to 1.8. This factor is used to increase the allowed lighting power 
when the shape of the room (the size and height) necessitates the use 
of additional lighting power to achieve certain levels of illuminance. 
The area factor that can be used to calculate some space type 
allowances is limited. For example, the allowance for sports playing 
areas, corridors, open offices, and mechanical rooms cannot be modified 
by an area factor, while the allowance for enclosed offices can be 
modified by an area factor of up to 1.55. Spaces that are used for 
multiple functions, such as auditoriums, conference, banquet, and 
meeting rooms, are allowed an additional lighting power adjustment 
factor of 1.5. By contrast, this adjustment for room dimensions is 
already built into the 1999 edition's space lighting power values, so 
adjustments for space dimensions are not permitted. The 1999 edition 
does allow some additional lighting power allowances to accommodate 
specific lighting needs. These include additional power for decorative 
lighting (1.0 Watt per square foot), additional power for VDT terminal 
lighting (0.35 Watts per square foot), and additional power for retail 
display lighting. In the latter case, either 1.6 Watts per square foot 
of specific display area is allowed for general merchandise 
highlighting, or 3.9 Watts per square foot of specific display area is 
allowed for valuable merchandise highlighting. This additional power is 
only allowed if the specified luminaries are installed and can only be 
used for the specific purpose noted.
    It is difficult to assess the actual impact from the use of the 
1999 edition's space-by-space method versus the 1989 edition's. This is 
because the allowed power density for a building will depend greatly on 
the space makeup of the building, the individual room dimensions 
(affecting the area factor adjustment) and any additional allowances 
that may apply. However, the average of all matching 1989 and 1999 
edition power density space values shows a 0.36 Watts per square foot 
decrease in the 1999 edition's values from those in the 1989 edition. 
Identical room geometry configurations (based on those used in the 
development of the 1999 edition's lighting power densities) were taken 
into account in reaching this conclusion. Furthermore, it is important 
to consider the items in both editions that can modify these lighting 
allowances. For example, the 1989 edition would allow the use of a 1.5 
additional lighting power adjustment factor for multipurpose spaces, 
such as ``Auditorium,'' ``Conference/Meeting Room,'' and ``Banquet/
Multi-Purpose Space.'' Whereas the 1999 edition would be even more 
energy efficient because there is no such area factor adjustment.
    Determining the impact of the additional power allowances in the 
1999 edition is difficult, since any comparison with values in the 1989 
edition uses either example buildings or lighting models. Using either 
example buildings or lighting models requires many assumptions 
regarding what is ``typical `` in each type of space and how each space 
is used. For example, in the 1989 edition, the base lighting power 
density for a mass merchandise store in a warehouse type setting is 3.3 
Watts per square foot. With the application of an appropriate area 
factor (1.05), the 1989 edition's adjusted

[[Page 46474]]

power allowance is 3.46 Watts per square foot. The 1999 edition starts 
with a base lighting power density for all retail establishments of 2.1 
Watts per square foot. The 1999 edition allows additional lighting 
power for certain lighting activities including retail sales lighting. 
These come in the form of an additional 1.6 Watts per square foot of 
lighted area for merchandise highlighting and 3.9 Watts per square foot 
of specific fine merchandise display. The application of these 
allowances will depend on the layout of the retail space and how and at 
what height lighting is employed. This is similar to how the area 
factor in the 1989 edition depends on the geometry of the individual 
space.
    Office space lighting has a similar difference between the two 
editions. The 1999 edition offers an additional power allowance for 
visual display terminal lighting. Spaces with decorative lighting 
similarly are allowed extra power only for the decorative lighting 
used. No such allowances are included in the 1989 edition's values.
    To make some assessment of the possible impact of these additional 
allowances, we developed characteristics of a space under the 1999 
edition whose total space lighting power allowance would match that of 
the 1989 edition. For this comparison, we determined what additional 
lighting power allowances would need to be applied to the 1999 
edition's base value to match the 1989 edition's value. This comparison 
allows for a determination of any stringency associated with the use of 
the low base numbers in the 1999 standard. In some of these cases a 
range of power values represents the possible variation in calculated 
values using the 1989 standard. The 1999 standard allows for only one 
base value. Table 5 presents comparisons for a variety of 
representative cases.

               Table 5.--Additional Lighting Power Allowance in the 1999 Edition Needed To Match the 1989 Edition Lighting Power Allowance
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          1989 edition adjusted total                                   Possible scenarios of use of additional power in
 Space type [Additional lighting type]               power                 1999 edition base power              1999 to equal 1989 edition value
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hotel Lobby [Decorative]..............  2.51..........................  1.7..........................  Permits 20 percent of the entire space to have
                                                                                                        decorative lighting.
Office--enclosed [Visual Display        2.38..........................  1.5..........................  Cannot reach the1989 edition's value (Max 1999
 Terminal].                                                                                             value = 1.85).
Office--open [Visual Display Terminal]  2.51..........................  1.3..........................  Cannot reach the 1989 edition's value (Max 1999
                                                                                                        value = 1.65).
Jewelry Retail [Highlight Merchandise]  5.88 to 7.40..................  2.1..........................  In most cases, one cannot reach the 1989
                                                                                                        edition's value (Max 1999 value = 6.00). Need to
                                                                                                        have 97 percent of the entire space covered with
                                                                                                        spotlighted fine merchandise displays, to reach
                                                                                                        the 1989 edition's lower value.
Fine Merchandise Retail [Highlight      3.36 to 4.23..................  2.1..........................  Need to have between 32 and 55 percent of space
 Merchandise].                                                                                          dedicated to spotlighted fine merchandise
                                                                                                        displays--or, more than 78 percent of the space
                                                                                                        dedicated to spotlighted general displays, to
                                                                                                        reach the 1989 edition's value.
Mass Merchandise (big box) Retail       3.30..........................  2.1..........................  75 percent of space dedicated to spotlighted
 [Highlight Merchandise].                                                                               general displays--OR--30 percent of space
                                                                                                        dedicated to spotlighted fine merchandise
                                                                                                        displays, to reach the 1989 edition's values.
Department Store Retail [Highlight      3.10 to 4.10..................  2.1..........................  Need to have between 26 and 51 percent of space
 Merchandise].                                                                                          dedicated to spotlighted fine merchandise
                                                                                                        displays, or over 62 percent of the space
                                                                                                        dedicated to spotlighted general displays, to
                                                                                                        reach the 1989 edition's values.
Food and Misc. Retail [Highlight        2.80..........................  2.1..........................  Need to have 43 percent of space dedicated to
 Merchandise].                                                                                          spotlighted general displays, to reach the 1989
                                                                                                        edition's values.
Service Retail [Highlight Merchandise]  2.84 to 3.57..................  1.05 to 1.32.................  Need to have between 46 and 92 percent of the
                                                                                                        entire space dedicated to spotlighted general
                                                                                                        displays, to reach the 1989 edition's values.
Mall Concourse [Highlight Merchandise]  1.40 to 1.85..................  1.8..........................  The 1999 value is within or close to possible
                                                                                                        1989 values.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In the case of the hotel lobby it would be possible to use the 
decorative lighting power credit in 20 percent of the entire space 
without exceeding the requirements of the 1989 edition, which is quite 
reasonable. However, in the case of the mall concourse example, no 
additional lighting power allowance is required for the 1999 edition 
lighting power allowance to equal or exceed the 1989 edition value. By 
contrast, the enclosed and open office examples show that the 1989 
edition lighting value cannot be achieved, even with the maximum 
allowance possible applied.
    In the case of Jewelry stores, in most cases one cannot reach the 
1989 value. Where one can reach the 1989 value, it would require an 
unreasonable 97 percent of the entire sales area to be covered with 
fine merchandise displays, in order to meet the 1989 value. In the Mass 
Merchandising, Food and Miscellaneous Retail and Service Retail 
categories, the additional areas of highlighted merchandise required to 
match the 1989 values are excessive and generally unrealistic. In the 
remaining two examples (fine Merchandise and Department Store) the 1989 
edition lighting values can be achieved with additional lighting power 
scenarios that are generally reasonable for some of the spaces, but 
only where low room cavity ratio values occur. Overall, these results 
indicate that the 1999 edition lighting values are more stringent, with 
the additional lighting power allowances more than compensated for by 
the reduction in base lighting power in the 1999 edition.
8. End Use Metering
    The 1989 edition had requirements for the subdivision of electrical 
power feeders by use category, to facilitate end-use metering in 
buildings with more than 250 kVA connected load. In addition it had 
provisions to check meter loads of individual tenants with more than 
100 kVA of connected load. The removal of requirements for

[[Page 46475]]

subdividing metering loads, in the 1999 edition, will make check 
metering and commissioning of these systems more difficult. In doing 
so, it will likely result in some increase in energy consumption.
9. Transformers
    The 1989 edition suggested that building transformers be selected 
to optimize the combination of no-load, part-load, and full-load 
losses, and had a requirement that an annual operating cost calculation 
be done and added to the electrical design documentation for buildings 
with total building transformers more than 300 kVA. The requirement has 
been removed from the 1999 edition. However, the 1989 edition did not 
provide for a comparison over multiple possible system designs, that 
might have produced more efficient options. Thus, the removal of the 
requirement is unlikely to have a significant impact on building 
efficiency.
10. Motors
    The 1989 edition had motor efficiency requirements for motors 
operating more than 500 hours per year. However, the efficiency levels 
included are less efficient than Federal manufacturing standards 
enacted in 1992 and thus have no impact on building efficiency.

B. Building Envelope

1. Air Leakage
    The 1989 edition provides a series of air-leakage standards or 
requirements that individual components must meet. The 1999 edition 
replaces all these standards with a requirement to use the National 
Fenestration Rating Council's, Procedure for Determining Fenestration 
Product Air Leakage, NFRC 400, as the test procedure. Table 6 compares 
the air leakage requirements for envelope openings in the two editions. 
The number in the right-hand column indicates that the 1999 edition 
permits more air leakage and is therefore less stringent.

                Table 6.-- Comparison of Air Leakage Requirements in the 1989 and 1999 Editions.
----------------------------------------------------------------------------------------------------------------
                                                                                                   1989-1999
             Product                       1989 edition                  1999 edition              difference
----------------------------------------------------------------------------------------------------------------
Windows:                            ...........................
    Aluminum Framed, Operable...  0.37 cfm/lon ft..............  0.4 cfm/ft \2\..............              +0.03
    Aluminum Framed, Jalousie...  1.5 cfm/f2...................  0.4 cfm/ft \2\..............              -1.10
    Aluminum Framed, Fixed......  0.15 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.25
    Vinyl Framed................  0.06 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.34
    Wood Framed, Residential....  0.37 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.03
    Wood Framed, Light            0.25 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.15
     Commercial.
    Wood Framed, Heavy            0.15 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.25
     Commercial.
Skylights.......................  0.05 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.35
Doors:                              ...........................
    Aluminum Sliding............  0.37 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.03
    Vinyl Sliding...............  0.37 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.03
    Wooden, Residential.........  0.34 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.06
    Wooden, Light Commercial....  0.25 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.15
    Wooden, Heavy Commercial....  0.10 cfm/ft \2\..............  0.4 cfm/ft \2\..............              +0.30
    Commercial Entrance, glazed.  1.25 cfm/ft \2\..............  1.0 cfm/ft \2\..............              -0.25
    Commercial Entrance, opaque.  1.25 cfm/f2..................  0.4 cfm/ft \2\..............              -0.85
    Residential Swinging........  0.50 cfm/ft \2\..............  0.4 cfm/ft \2\..............              -0.10
Aluminum Wall Sections..........  0.06 cfm/ft \2\..............  Not covered.................                  +
----------------------------------------------------------------------------------------------------------------

The impact of these changes on energy efficiency is hard to evaluate. 
Air leakage requirements for windows are less stringent for six window 
types and more stringent in one window type in the 1999 edition. 
Skylight requirements are more stringent in the 1999 edition than in 
the 1989 edition. Doors are more stringent for three types and less 
stringent for five other types, in the 1999 edition. Jalousie windows 
are not a predominate window type in commercial construction, but there 
has been a significant increase in allowed leakage rate for other 
window types under the 1999 edition. Therefore, the overall impact in 
comparing the requirements for window air leakage is a reduction in 
stringency.
    For doors, there are significant increased leakage rates for wooden 
doors and slight increased leakage for sliding doors. However for the 
categories of ``Commercial entrance doors'' and for ``All other 
commercial doors,'' there are expected to be significant reductions in 
allowed leakage. Because of the predominance of commercial steel doors 
in the latter category, we believe door air leakage requirements are 
more stringent in the 1999 edition.
    The 1999 edition does include additional requirements for loading 
dock weather seals in colder climates (greater than 3,600 heating 
degree days, base 65 degrees Fahrenheit) and also a requirement for 
vestibules in commercial building entrance doors. Vestibules are not 
required in climates of less than 1,800 heating degree days, base 65 
degrees Fahrenheit; in buildings of less than four stories; where doors 
open directly from a dwelling unit; where doors open directly from a 
space less than 3,000 square feet in area; in buildings entrances with 
revolving doors; and where doors are used primarily to facilitate 
vehicular movement or material handling and adjacent personnel doors. 
These requirements are not present in the1989 edition. The combination 
of the more stringent requirements for ``commercial'' doors and loading 
dock and vestibule requirements should improve energy efficiency in 
buildings where they are required.
    We would expect there to be fewer doors than windows in most 
commercial buildings. We therefore expect an overall decrease in 
stringency due to air leakage under the 1999 edition.
2. Insulation Installation
    The 1999 edition requires that insulation be installed in 
substantial contact with the inside surface of cavities. It also 
requires that lighting fixtures, heating, ventilating, and air-
conditioning, and other equipment not be recessed in such a manner as 
to affect the insulation performance. Finally, the 1999 edition bans 
installation of insulation on suspended ceilings with

[[Page 46476]]

removable ceiling panels. The 1989 edition does not address this 
subject at all. These 1999 edition insulation installation requirements 
are expected to save energy in commercial buildings.
3. Allowance for Speculative Buildings
    Buildings constructed on speculation that they will be leased or 
occupied by as yet unknown occupants are referred to as ``speculative'' 
buildings in the 1999 edition. Speculative buildings are often designed 
and the envelope constructed prior to the final occupancy being known. 
Both the 1989 and 1999 editions cover this issue, albeit in somewhat 
different fashion. The 1989 edition sets the most stringent envelope 
requirements likely to be encountered to be installed in the building 
from the start, while the 1999 edition allows a less stringent envelope 
to be installed to accommodate a less demanding occupancy (such as a 
semi-heated warehouse), but then requires an upgrade to the envelope 
efficiency if the building use changes to a more demanding occupancy 
(such as office space). We believe that under the 1999 edition the 
transition from a semi-heated space (such as the conversion of a 
warehouse heated for freeze protection only to a conditioned space for 
other use such as office) would entail the addition of heating 
capacity, and likely cooling capacity in most climates. Similarly, 
changes in lighting would likely occur. Building inspections would 
normally be required which would trigger a review of energy code 
requirements. While these approaches differ, we do not believe the 
difference will impact the overall energy use of commercial buildings.
4. Envelope Thermal Transmittance in Cold Climates
    The 1989 edition has an explicit set of requirements for the 
building envelope (wall, roof, and fenestration) for cold climates with 
more than 15,000 heating degree days, base 65 degrees Fahrenheit. The 
1999 edition addresses these cold climates in three bins, or groupings 
of ranges of degree days, that are slightly different from the 1989 
edition. These three bins include criteria for buildings in climates 
with heating degree day, base 65 degrees Fahrenheit between 12,601 and 
16,200 (bin 24), between 16,201 and 19,800 (bin 25) and more than 
19,801 (bin 26). The envelope criteria vary with differences in 
construction (see Table 7). The U-factor requirements in the 1999 
edition are generally less stringent. However, the only U.S. climate in 
the 1989 or 1999 edition's weather data that would fall under the 
``cold climate'' requirements would be Barrow Alaska. Thus we expect 
any impact to be negligible because of the small amount of construction 
in Barrow and similar smaller cold climate communities.

 Table 7.--Differences in Building Envelope Thermal Requirements in Cold
               Climates Between the 1989 and 1999 Editions
------------------------------------------------------------------------
                                1989 edition cold
                                climate (15,000 HDD65)       (16,201-19,800
                                  requirements       HDD65) requirements
------------------------------------------------------------------------
Opaque Wall.................  U-0.053 for large     U-0.045 to 0.071,
                               buildings.            depending on type
                              U-0.040 for small      of wall.
                               buildings.
Fenestration................  U-0.52 (for window    U-0.43, for the
                               to wall ratios of     corresponding WWR
                               less than 0.2 for     values.
                               large buildings and
                               0.15 for small
                               buildings).
Roof........................  U-0.024.............  U-0.027 to 0.049,
                                                     depending on type
                                                     of roof.
Floor Over Unconditioned      U-0.023.............  U-0.033 to 0.064,
 Space.                                              depending on type
                                                     of floor.
Slab on Grade Insulation....  R-15 for 48 inches..  R-15, for 24 inches.
Skylight....................  Not allowed.........  U-0.95.
------------------------------------------------------------------------

5. Skylight Thermal Transmittance and Solar Heat Gain
    For buildings whose overall roof U-factor, including skylights, is 
less than the 1989 edition's requirements, no separate skylight 
requirements must be met. For buildings that cannot meet this 
requirement, the 1989 edition contains skylight thermal transmittance 
requirements that are a function of heating degree days, base 65 
degrees Fahrenheit, as well as provides credit toward the overall roof 
U-factor requirement, where lighting controls are used to reduce 
lighting consumption. The 1999 edition has separate requirements for 
glass skylights with curbs, plastic skylights with curbs, and skylights 
without curbs, which vary by climate bin. The least stringent of these 
are for glass skylights with curbs. The 1999 edition provides no 
envelope credits for using lighting controls in conjunction with 
skylights. A comparison of the 1989 and 1999 editions' U-factor 
requirements is shown in Table 8. The original 1989 edition had U-
factors based on center of window measurements. The 1999 edition has U-
factors based on whole window measurements. We used U-factors based on 
whole window measurements which are incorporated in Addenda F to the 
1989 edition, for an accurate comparison.

              Table 8.--Comparison of Skylight U-factor Requirements in the 1989 and 1999 Editions
----------------------------------------------------------------------------------------------------------------
             Climates with:                       1989 edition                        1999 edition
----------------------------------------------------------------------------------------------------------------
HDD65 <8000.............................  U-0.7                         U-1.17 to 1.98 (glass).
HDD65 [ge]8000..........................  U-0.52                        U-0.88 to 1.17 (glass).
Skylight curbs all climates.............  U-0.21                        Included in U-factor for skylights with
                                                                         curbs.
----------------------------------------------------------------------------------------------------------------

    Furthermore, the 1989 edition limits the maximum allowable percent 
of skylight area, based on skylight visible light transmittance, number 
of heating degree days, base 65 degrees Fahrenheit, number of cooling 
degree hours, base 80 degrees Fahrenheit, foot candle level, and 
interior lighting power density. The allowable percent of roof area in 
skylight ranges from about 2 percent to 12 percent for specific 
combinations. The 1999 edition limits skylights to 5 percent of roof 
area.
    The 1989 edition is more stringent than the 1999 edition in terms 
of

[[Page 46477]]

required skylight U-factor. On the other hand, the total area of 
skylight that can be installed is less in the 1999 edition. In other 
words, the 1999 edition has greater restriction on the total roof area 
in skylights, but does allow skylights with a higher U-factor to be 
used. This essentially allows the user of the 1999 edition to put in a 
smaller amount of less efficient skylight than the 1989 edition.
    The 1989 edition does not have any requirements for skylight solar 
heat gain. The 1999 edition does include specific solar heat gain 
coefficient requirements for skylights. Solar heat gain coefficient 
values for glass skylights range from 0.16 in very warm climates to 
``No Requirement'' in very cold climates. Implicit in the1989 edition's 
thermal transmittance requirements, however, are SHGC values associated 
with the required glass. With required U-factors at 0.7 and 0.52 for 
skylights, skylights would have to be constructed with glazing similar 
to double pane and double low-emissivity glazing. Such construction 
would have solar heat gain coefficient values of 0.68 and 0.59. Using 
this logic, a comparison of skylight solar heat gain coefficient values 
is constructed in Table 9. Values are taken for five percent of the 
roof area in skylights, as this is the maximum prescriptive level in 
the 1999 edition. The upper range of solar heat gain coefficient values 
in the 1999 edition column is for cooler climates within each range.

  Table 9.--Comparison of Solar Heat Gain Coefficients in the 1989 and
                              1999 Editions
------------------------------------------------------------------------
        Climates with:          1989 edition SHGC    1999 edition SHGC
------------------------------------------------------------------------
HDD65 [le]7,500...............  0.68               0.16 to 0.62.
HDD65 [ge]7,500 <10,801.......  0.59               0.36 to 0.64.
HDD65 10,801.......  0.59               No requirement.
------------------------------------------------------------------------

    The 1999 edition solar heat gain coefficient requirement is more 
stringent for virtually all locations in the US. The 1989 edition does 
have lower solar heat gain coefficient requirements in very cold 
climates, but since solar gain is a net benefit in these climates, 
restricting solar gain provides no benefit.
    The lack of data on the amount of skylight in various parts of the 
country makes it inappropriate for us to reach a conclusion as to the 
net impacts of these changes.
6. Slab-On-Grade and Below Grade Wall Insulation
    Slab-on-grade insulation requirements are nonexistent in both 
editions in warm climates. For cooler climates, the 1989 edition 
requires between R-7 and R-8 for vertical insulation, extended 24 
inches deep, whereas there are effectively no requirements for slab 
insulation in the 1999 edition in the continental U.S. For heated 
slabs, the 1989 edition requires an additional insulation level of R-2, 
to that required for unheated slabs, in all cases. For below grade 
walls, the 1989 edition requires insulation levels from R-7 to R-16, 
for the first story below grade, depending on location. Whereas there 
are effectively no requirements for below grade wall insulation in the 
1999 edition, until above 9,000 heating degree days, base 65 degrees 
Fahrenheit (much of Alaska and some northern Minnesota locations). The 
reduction of slab-on-grade and below grade wall insulation requirements 
in the 1999 edition will result in higher heating loads in cold 
climates, particularly for small buildings, resulting in more energy 
use. While a reduction in stringency, the impact of the removal of 
below grade or slab wall insulation is tempered by the insulating 
effect of the surrounding earth, relative to removing insulation from 
envelope components exposed to the air and sun (such as walls and 
roofs).
7. Roof Thermal Transmittance
    We looked at roof thermal transmittance requirements first by 
estimating the building footprint area (assumed to approximate the roof 
area) by dividing the floor area by the number of floors for each 
building type. We then applied the Commercial Building Energy 
Consumption Survey statistical weights to each building type, to 
develop a table of the estimated roof area. This was done for each roof 
surface type classification for each of the 18 building use 
classifications in the 1992 Commercial Building Energy Consumption 
Survey. There are 17 Commercial Building Energy Consumption Survey roof 
surface classifications, which were aggregated into the three roof 
types in the 1999 standard as shown in Table 10, below. Where a 
significant fraction of a particular roof surface classification could 
be divided into one or more construction categories, estimates were 
made of the relative percentage in each category and are shown in 
parentheses in Table 10. Finally, the fraction of estimated roof area 
for each roof construction is shown for non-residential, semi-heated, 
and residential space types.

               Table 10.--Estimated Roof Area Fractions by 1999 Edition Roof Construction Category
----------------------------------------------------------------------------------------------------------------
                                     CBECS 1992 roof            Estimated roof area fraction  (in percent)
 1999 edition room construction          surface        --------------------------------------------------------
                                     classifications      Non-residential    Semi-heated \a\    Residential \b\
----------------------------------------------------------------------------------------------------------------
Insulation Entirely Above Deck.  Built-up, Built-up &                 50.2               45.9               45.6
                                  metal, Built-up & s/m
                                  ply, Composite, Foam/
                                  Styrofoam, Single/
                                  multiple ply (33%),
                                  Shingles & built-up
                                  (50%).
Metal Building.................  Metal/Rubber (80%),                  16.5               32.9                4.9
                                  Metal Surfacing
                                  (80%), Single/
                                  multiple ply (33%).

[[Page 46478]]

 
Attic and Other................  Concrete Roof, Metal/                33.3               21.2              49.4
                                  Rubber (20&), Metal
                                  Surfacing (20%),
                                  Other (specify),
                                  Shingles & metal,
                                  Shingles & s/m ply,
                                  Shingles (not wood),
                                  Single/multiple ply
                                  (33%), Shingles &
                                  built-up (50%), Slate
                                  & shingles, Slate or
                                  tile, Wooden
                                  materials.
----------------------------------------------------------------------------------------------------------------
\a\ Non-refrigerated warehouse assumed.
\b\ Lodging buildings only.

    Metal surfacing (about 13% of floor area) can be considered part of 
a metal building roof or a roof with metal joists (big box buildings 
such as Walmarts). The 80/20 split here allocates most of these 
surfaces to metal buildings which are the more prevalent class of new 
commercial construction. The shingles/slate, tile/wooden materials, are 
likely to be in place on roofs with attics or single rafter roofs, 
because they rely on roof pitch to shed water. The remaining categories 
cover a variety of combinations of materials, mainly synthetic/rubber 
surfaces. Some of these may be flat roofs, but they could be metal 
joists roofs or deck roofs. We allocated these evenly over the 1999 
edition's roof construction categories.
    The fractions of roof types estimated were used to weight the 
required U-factors from the 1999 edition for each climate and for each 
category of building, non-residential, semi-heated, and residential.
    The results shown in Table 11 suggest that for most non-residential 
buildings, the 1999 edition has more stringent roof U-factor 
requirements in warm to mild climates (significantly so in Knoxville 
and Los Angeles, moderately so in Orlando, Seattle, and Shreveport, and 
slightly so in Fresno). It is slightly less stringent in the cooler 
climates of Denver, Detroit, and Providence, and is significantly less 
stringent in Minneapolis and Phoenix. Overall, we expect a slight 
increase in heating energy use and slight decrease in cooling energy 
use for most non-residential buildings from these requirements.
    The semi-heated building category in the 1999 edition shows a 
substantial increase in average U-factor for all buildings, which is 
expected to result in increased energy use due to increased heating 
loads for these buildings.
    A comparison of the requirements for the residential space category 
in the 1999 edition shows a reduction in U-factor (increase in 
stringency) for all climates except Los Angeles, which shows a 
substantial increase in U-factor (decrease in stringency).
    Overall, it is expected that the changes in U-factor requirements 
in the 1999 edition will result in some increase in heating energy use, 
primarily as a result of the significant changes in requirements for 
semi-heated spaces. It is expected that it will also result in some 
decrease in cooling energy use in most (but not all climates).

                                    Table 11.--Average Roof U-factor Required
----------------------------------------------------------------------------------------------------------------
                                                                   1999 edition                    Change 1989-
              City                 1989 edition  ------------------------------------------------    1999 Non-
                                                      Non-res       Semi-heated     Residential       res\1\
----------------------------------------------------------------------------------------------------------------
Denver..........................           0.051           0.054           0.123           0.045          -0.003
Detroit.........................           0.053           0.054           0.123           0.045          -0.001
Fresno..........................           0.059           0.054           0.172           0.045           0.005
Knoxville.......................           0.110           0.054           0.149           0.045           0.056
Los Angeles.....................           0.100           0.070           0.202           0.200           0.030
Minneapolis.....................           0.045           0.051           0.123           0.045          -0.006
Orlando.........................           0.063           0.054           1.140           0.045           0.009
Phoenix.........................           0.046           0.054           0.172           0.045          -0.008
Providence......................           0.053           0.054           0.123           0.045          -0.001
Seattle.........................           0.064           0.054           0.149           0.049           0.010
Shreveport......................           0.066           0.054           0.172           0.045          0.012
----------------------------------------------------------------------------------------------------------------
\1\ Negative U-factors indicate decreased stringency.

8. Floors Over Unconditioned Spaces
    For each climate, the 1989 edition provides a single prescriptive 
U-factor for floors, while the 1999 edition provides nine possible U-
factors (or R-values) depending on building type and floor type. The 
range of requirements for the 1999 edition addresses wood framed, steel 
framed, and mass (concrete) floor construction separately. Typically, 
wood framed floors have the lowest (most stringent) U-factor 
requirement, while mass floors have the highest (least stringent) U-
factor. The 1999 edition is typically more stringent for wood framed 
and steel framed floors, and less stringent for mass floors in 
nonresidential (and residential) buildings. The 1999 edition is less 
stringent for semi-heated buildings. See Table 12.

[[Page 46479]]



                         Table 12.--Comparison of Floor Over Unconditioned Space U-factor Criteria in the 1989 and 1999 Editions
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 1999 edition                                  1989-1999 difference
                                                      --------------------------------------------------------------------------------------------------
                                                               Non-residential                    Semi-heated                    Non-residential
                  City                   1989 edition --------------------------------------------------------------------------------------------------
                                          all floors      Wood                             Wood                             Wood
                                                        frame &     Steel       Mass     frame &     Steel       Mass     frame &     Steel       Mass
                                                         other      joists                other      joists                other      joists
--------------------------------------------------------------------------------------------------------------------------------------------------------
Orlando................................         0.28            No requirement
                                                   No requirement
                                                        0.280
--------------------------------------------------------------------------------------------------------------------------------------------------------
Phoenix................................         0.19       0.051      0.052      0.137           No requirement              0.139      0.138      0.053
------------------------------------------------------
------------------------------------------------------                                                                  --------------------------------
Shreveport.............................         0.11                                                                         0.059      0.058     -0.027
------------------------------------------------------                                                                  --------------------------------
Fresno.................................         0.10                                                                         0.049      0.048      0.037
--------------------------------------------------------------------------------------------------------------------------------------------------------
Knoxville..............................         0.074      0.051      0.052      0.107      0.660      0.069      0.322      0.023      0.022     -0.033
------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------
Denver.................................         0.049      0.033      0.052      0.087      0.066      0.069      0.322      0.016     -0.003     -0.038
------------------------------------------------------
------------------------------------------------------                                                                  --------------------------------
Providence.............................         0.048                                                                        0.015     -0.004     -0.039
------------------------------------------------------                                                                  --------------------------------
Minneapolis............................         0.040                                                                        0.007     -0.012     -0.047
--------------------------------------------------------------------------------------------------------------------------------------------------------

9. Opaque Wall Thermal Transmittance
    The 1989 edition provides a single prescriptive U-factor for 
lightweight walls and a range of possible U-factors for mass walls 
(depending on thermal mass, percent fenestration, and internal load 
density), while the 1999 edition provides 12 possible U-factors (or R-
values) depending on building type and wall construction. The maximum 
thermal transmittance requirements for mass walls in the 1999 edition 
generally fall within the range of allowable values in the 1989 
edition, except for semi-heated buildings where in all cases the 1999 
criteria are less stringent. However, since buildings in the semi-
heated category are expected to have relatively low heating loads (due 
to the low internal temperature and limited heating capacity) and no 
cooling loads, the reduction in stringency is expected to have a 
minimal impact.
    The difference in criteria for lightweight walls between the 1989 
and 1999 editions varies, with some wall types being more stringent in 
some locations and other less stringent. In general, wood framed wall 
requirements in the 1999 edition are most likely to be more stringent 
than corresponding requirements in the 1989 edition.
    To compare requirements for mass walls in the1989 edition, we used 
the Alternate Component Packages tables to determine U-factor 
requirements for 8 inch solid concrete and solid grouted concrete block 
mass walls (Heat Capacity  15 Btu/ft\2\-F) as well as for 8 
inch unfilled or insulated concrete block walls (10 Btu/ft\2\-F < Heat 
Capacity < 15 Btu/ft\2\-F). We did this for insulation on the inside of 
the wall; integral with the wall; and on the outside of the wall, under 
each of the three internal load density (ILD) ranges in the Alternate 
Component Packages tables. This was done for the 11 locations and for 
18 percent and 38 percent window to wall area ratios. The requirements 
used were based on interpolation across the tabulated fenestration 
levels. For each internal load density range, we averaged together all 
calculated U-factor requirements. These results are shown in Table 13. 
In addition, we show the 1999 edition's U-factor requirements by that 
edition's three space-type categories (non-residential, residential, 
and semi-heated).

                                                                          Table 13.--Mass Wall Requirements Comparison
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               1989 edition mass wall requirements    1999 edition mass wall requirements                     U-Factor difference
                                                             --------------------------------------------------------------------------------------------------------------------------------------
                          Location                                    Interior load density
                                                             ---------------------------------------     Non-     Residential  Semi-heated      Non-           Non-        Residential     Semi-
                                                                  Low         Medium        High     residential                            residential    residential         \b\         heated
---------------------------------------------------------------------------------------------------------------------------------------------------------------\a\--------------------- ----\c\----
ORL.........................................................        0.624        0.649        0.636         0.58        0.151         0.58       -0.062         -0.473          -0.044
PHX.........................................................        0.404        0.403        0.400         0.58        0.151         0.58        0.179         -0.253           0.176
LOS.........................................................        0.737        0.791        0.793         0.58        0.151         0.58       -0.212         -0.586          -0.157
SHR.........................................................        0.301        0.327        0.328         0.58        0.123         0.58        0.252         -0.178           0.279
FRS.........................................................        0.293        0.307        0.311         0.58        0.151         0.58        0.271         -0.142           0.287
KNX.........................................................        0.166        0.185        0.188        0.151        0.104         0.58       -0.036         -0.062           0.414
SEA.........................................................        0.123        0.140        0.147        0.151        0.104         0.58        0.007         -0.019           0.458
DET.........................................................        0.100        0.107        0.109        0.123         0.09         0.58        0.015         -0.010           0.480
DEN.........................................................        0.131        0.144        0.144        0.123         0.09         0.58       -0.021         -0.041           0.449
PRV.........................................................        0.100        0.107        0.109        0.123         0.09         0.58        0.015         -0.010           0.480
MNP.........................................................        0.078        0.087        0.088        0.104         0.09         0.58        0.017          0.012          0.502
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Non-Residential versus average of Medium and High Interior Load Density cases.

[[Page 46480]]

 
\b\ Residential versus Low Interior Load Density case.
\c\ Semi-heated versus Low Interior Load Density case.

    The difference in required U-factors for typical buildings is also 
shown in Table 13. For this comparison, we have assumed that most non-
residential buildings in the 1999 edition would fall into either the 
medium or high interior load density ranges of the 1989 edition. The 
average U-factor for both of these interior load density ranges was 
used in the comparison. Most residential buildings would fall into the 
low interior load density range of the 1989 edition. Most semi-heated 
building spaces (assumed to be similar to warehouse buildings) would 
likely fall under the low interior load density range of the 1989 
edition. As can be seen from the table, the requirements of the 1999 
edition are more stringent for residential buildings, in almost all 
climates. This is particularly so in moderate to warm climates. The 
1999 edition is considerably less stringent for semi-heated buildings 
in all but Orlando and Los Angeles, where heating losses are not 
expected to be significant. The 1999 edition is generally less 
stringent for non-residential construction in moderate to warm climates 
and slightly less stringent for cool or cold climates. Overall, it is 
expected that the reduced U-factor requirements for mass walls in the 
non-residential and semi-heated category will result in increased 
heating energy use over the 90.1-1989 mass wall requirements.
10. Window Thermal Transmittance and Solar Heat Gain
    The 1989 edition does not specifically provide a prescriptive 
approach to window thermal transmittance or solar heat gain, but rather 
treats windows as a component of the building wall, where the wall must 
have certain overall heating and cooling performance to show 
compliance. However, the ACP (Alternate Component Packages) tables, 
which set out prescriptive requirements for the building envelope, 
provide tables of maximum percentage of wall glazing as a function of 
window U-factor, shading coefficient, projection factor, and building 
internal gains. The 1999 edition, by contrast, provides prescriptive U-
factor requirements and Solar Heat Gain Coefficient requirements for 
particular combinations of percentage of glazing and building category 
(non-residential, residential, semi-heated), simplifying use and 
enforcement. Both editions require the use of an energy tradeoff 
methodology for buildings with very high percentages of window area 
(typically greater than 50 percent).
    For our analysis, we assumed the mid-internal gain range of the ACP 
tables (1.51-3.00 W/ft\2\) as being typical of the non-residential 
building loads, and the low-internal gain range of the ACP tables (0.0-
1.5 W/ft\2\) as being typical of semi-heated buildings such as 
warehouses. For residential space types such as hotels and hospitals, 
we assumed either low-or mid-internal gain ranges of the ACP tables 
could be appropriate in the 1989 edition. For multi-family high rise 
buildings we assumed low-internal gain ranges.
    For these typical levels of internal gains, the requirements for 
window thermal transmittance in residential and non-residential 
buildings are very similar in both editions. The 1989 edition is 
somewhat more stringent in cold climates in buildings with a high 
percentage of glazing. The 1999 edition is marginally more stringent in 
the rest of the country. For semi-heated buildings, the requirements in 
the 1999 edition are less stringent, except for in warm climates where 
both editions require single pane glass.
    Window solar heat gain requirements in the 1999 edition are 
typically more stringent in buildings with lower glazing areas (less 
than 30 percent), but often less stringent in buildings with higher 
glazing areas (38 percent or 45 percent). Maximum solar heat gain 
requirements do not exist for semi-heated buildings in the 1999 
edition. However, limiting solar heat gain does not reduce energy use 
for a building that is only heated.
    For windows with northern orientations, the 1999 edition generally 
allows greater solar heat gain per window area than the 1989 edition. A 
review of six of the seven building types (not including warehouse 
buildings which are commonly semiheated buildings) in the quantitative 
analysis suggested that approximately 73% of the floor area of these 
buildings would be in buildings with glazing fractions of less than 
30%. This suggests that overall, the 1999 edition is more energy 
efficient in reducing solar heat gain in most buildings. It is somewhat 
less efficient with regard to window thermal transmittance, 
particularly in cold climates.
11. Opaque Doors
    The 1999 edition contains explicit U-factor requirements for both 
swinging and non-swinging doors, with requirements ranging from a U-
factor of 0.5 (for both door types in cold climates) to 1.45 for 
uninsulated doors of both types. An insulated metal door or a solid 
wood door requires a U-factor of 0.5. Glass doors that are more than 
one-half glass are considered to be equivalent to vertical fenestration 
and would need to meet vertical glazing requirements. The 1989 edition 
does not explicitly deal with either opaque or glazed doors, but 
instead treats them as part of the overall wall requirement. Opaque 
doors are part of the opaque wall, glass doors are part of the glazed 
area. Since the required thermal performance of opaque doors in the 
1999 edition is generally worse than that of the surrounding opaque 
wall area, and the opaque door requirements are included in the overall 
wall requirements of the 1989 edition, the requirements of the 1999 
edition are less stringent. Doors represent a small percentage of the 
wall area of multistory buildings. They also represent a fairly small 
percentage of the wall area of many large single story buildings. Most 
commercial entrance doors are glazed, reducing the impact of the 
difference in opaque door requirements. We therefore conclude that the 
energy impact of this change is likely to be small for most buildings. 
However, in individual buildings with a significant number of doors, 
such as some warehouses, the impact may be significant.

C. Mechanical Equipment and Systems

1. Load Calculations and Sizing
    The 1999 edition has no explicit sizing requirements for heating 
ventilation and air-conditioning systems. The1989 edition requires the 
use of a computational procedure for load calculations, and it details 
selection of indoor and outdoor design temperature, the use of Standard 
62-89 for minimum ventilation, and a selection of allowed sources for 
internal gain data. The 1989 edition also explicitly allows a ten 
percent safety factor for steady-state design loads and additional 30 
percent and ten percent multipliers beyond that to account for heating 
and cooling pick-up loads. However, these additional parameters 
represent typical values or sources for sizing calculation data. The 
omission of explicit sizing requirements for heating ventilation and 
air-conditioning systems, while unlikely to have much impact on large 
commercial buildings, which are typically designed by

[[Page 46481]]

engineering professionals, could have a significant impact on smaller 
commercial buildings, especially design-build facilities. The inclusion 
of explicit maximum safety factors in the 1989 standard recognizes the 
tendency for much larger values to be used by system designers. The 
exclusion of such factors in the 1999 standard has the potential for 
significantly oversizing equipment, resulting in operating 
inefficiency.
2. Separate Air Distribution Systems
    The 1989 edition requires that zones with special process, 
temperature, and/or humidity requirements, either be served by air 
distribution systems separate from those used to satisfy zones 
conditioned for comfort only, or have provisions to allow control for 
comfort conditioning only. An exception to this allows up to 25 percent 
of the air flow serving primarily process systems to be directed for 
comfort cooling only needs with no system design modification. This 
exception might be used for office space in an industrial facility. 
This requirement provides the ability to operate the primary heating 
ventilation and air-conditioning systems for comfort conditioning only 
when processes are not operating. The 1999 edition has no requirements 
explicitly for systems and equipment used for process applications. 
However, where systems would also serve spaces conditioned for comfort 
only, the equipment and system requirements of the 1999 edition would 
apply. In particular, requirements referring to zone isolation, 
dehumidification, and simultaneous heating and cooling would address 
most of the issues addressed by the separate air distribution system 
requirement in the 1989 edition. This will result in a minor reduction 
in stringency in a limited number of buildings.
3. Temperature Controls
    The 1999 edition has an additional requirement that all zone and 
loop controllers shall incorporate control error correction. In 
addition, it explicitly requires a set point overlap restriction when 
the heating and cooling to a zone are controlled by separate 
thermostats within that zone. In the 1989 edition, it is not clear 
whether individual thermostats are required that control both heating 
and cooling to a 5 degree Fahrenheit deadband, or whether it means that 
the space should be controlled to provide a 5 degree Fahrenheit 
deadband. The additional requirements make the 1999 edition clearer as 
to the requirements and better at controlling room temperature and will 
limit reheating and recooling done by separate systems, which will 
provide improved efficiency over the 1989 edition.
4. Off-Hour Controls and Setback
    The 1999 edition requirements for off-hour controls are limited to 
systems with heating or cooling capacity greater than 65,000 Btu per 
hour and fan system power greater than \3/4\ horsepower. The 
requirement for off-hour controls in the 1989 edition are for systems 
greater than two kilowatts. Exceptions are also made for heating 
ventilation and air-conditioning systems serving hotel or motel guest 
rooms. In these cases the 1999 edition is less stringent. However, the 
optimum start controls required in the 1999 edition for large systems, 
should reduce the number of hours needed to bring the building to 
operating temperature.
    The 1989 edition allows either independent shut-off controls or 
setback controls to reduce heating and cooling to the zone. The 1999 
edition requires automatic shutoff controls for the supply of 
conditioned air, outside air, and exhaust air to each independent 
isolation area, as well as automatic shutdown controls. However, it 
specifically allows substitution of a system air flow reduction in the 
non-occupied zones, but limits the total volume of air to those zones 
to 14 percent of the system airflow. The 1999 edition, by requiring 
maximum setback air volumes, has explicit, and therefore more 
stringent, off-hour requirements. These would be achieved by simple 
thermostat setback. Both editions incorporate different exceptions to 
these off-hour requirements for multi-zone systems. Our limited data on 
commercial building multi-zone systems and operating schedules is 
insufficient to evaluate these exceptions.
5. Dampers
    The 1999 edition requires motorized dampers in stair and elevator 
shafts and in all outdoor air supply exhaust hoods, vents, and 
ventilators. Gravity dampers are acceptable on buildings less than 
three stories and of any height in buildings in climates with less than 
2,700 heating degree days, base 65 degrees Fahrenheit. These damper 
performance requirements are more stringent than similar requirements 
in the 1989 edition. However, the requirements in the 1999 edition 
pertain to fewer systems (only to systems larger than 65,000 Btu per 
hour). The 1989 edition requires dampers (motorized or gravity) or 
other means of volume shut-off or reduction. It exempts supply and 
exhaust systems less than or equal to 3,000 cubic feet per minute, in 
warm climates (less than or equal to 3,000 heating degree days, base 65 
degrees Fahrenheit). Overall, the 1999 edition is considerably more 
stringent for large systems, but is less stringent for small systems in 
climates above 3,000 heating degree days, base 65 degrees Fahrenheit.
6. Humidity Control
    The 1989 edition had a requirement that any humidity control device 
(humidistat) be capable of limiting the use of fossil fuel or electric 
energy to provide relative humidities of greater than 30 percent or 
less than 60 percent. This range limit setpoint requirement for zone 
humidification is not included in the 1999 edition. Instead a 
requirement for having the capability to prevent simultaneous 
humidification or dehumidification was added, with an exception for 
zones with tight humidity requirements, approved by local authorities, 
or for desiccant systems used in series with evaporative cooling. 
Minimum impact is expected from this change as both editions 
effectively require systems with both humidification and 
dehumidification to have the controls to limit possible waste of energy 
that would result from simultaneous humidification and 
dehumidification.
7. Radiant Heating
    The title, purpose, and scope of the 1989 edition do not include 
unenclosed spaces, and has no requirements for heating such spaces. 
Hence, warm air heating systems may be used. By specifically including 
such spaces as loading docks without air curtains in the 1999 edition's 
title, purpose, and scope, and requiring radiant heating systems 
(excluding warm air systems), energy will be saved by requiring more 
efficient systems for that application.
8. Ventilation
    The 1989 edition requires ventilation systems be designed capable 
of providing the ventilation levels prescribed in Standard 62-1989. The 
1989 edition did not set the ventilation rate, but rather specified a 
minimum operational ventilation rate the system must be designed to 
provide. Operation of a system at higher or lower ventilation rates is 
allowed under the 1989 edition. The 1999 edition omits these 
requirements. No savings or loss in efficiency should occur from this 
specific change.
    Further, the new requirements in the 1999 edition for automatic 
ventilation controls for high occupancy areas make the 1999 edition 
more stringent than the

[[Page 46482]]

1989 edition and should provide some energy savings.
9. Pipe and Duct Insulation
    The 1999 edition has slightly less stringent pipe insulation 
requirements than the 1989 edition for most building applications. The 
1999 edition does not require insulation of piping unions in heating 
systems or hot water piping between the shutoff valve and coil (up to 4 
feet of pipe), in conditioned spaces. It requires more insulation on 
higher temperature ( 250 F) piping, and less insulation on 
lower temperature heating system and service hot water piping. In 
contrast, the 1989 edition requires more insulation on low temperature 
cooling system piping. Overall, there appears to be some small 
reduction in insulation requirements. However, since the piping is 
insulated under both standards, the incremental reduction in insulation 
is expected to have minimal impact.
    The 1999 edition has significantly less stringent duct insulation 
requirements for some categories of ducts than the 1989 edition. For 
cooling only ducts, the 1999 edition requires generally lower 
insulation levels for ducts located outside the building, and 
insulation levels at or lower than required in the 1989 edition for 
most spaces inside the building. The 1999 edition, generally requires 
higher insulation levels for ventilated attics and for unvented attics 
with non-insulated attic decks, which can be high temperature areas of 
the building. It requires no insulation for indirectly conditioned 
spaces including return air plenums.
    For heating only ducts, the 1999 edition requires somewhat less 
insulation on exterior heating ducts, except in the most extreme 
heating climates, where it requires more than the 1989 edition. It 
requires very little insulation on heating-only ductwork located inside 
the building envelope.
    For return ducts located exterior to the building, the 1999 edition 
requires lower insulation levels than the 1989 edition. The lower duct 
insulation requirements are likely to be most significant for heating-
only ducts in climates where insulation is not required for particular 
attics or unconditioned spaces. The reduction in the minimum insulation 
level for cooling only ductwork is significant for central systems that 
rely on year round cooling availability (such as variable air volume or 
dual duct systems). Both insulation reductions will decrease energy 
efficiency of the 1999 edition.
    Finally, the 1999 edition does not restrict the use of pressure 
sensitive tape at seal level C for supply pressures up to 2 inches of 
pressure, whereas the 1989 edition restricts its use for seal class C 
above 1 inch. Research is ongoing regarding the impact of this, 
however, we believe that there is a potential reduction in energy 
efficiency with the 1999 edition.
10. Heat Recovery
    New requirements in the 1999 edition for exhaust air heat recovery 
for systems of 5,000 cubic feet per minute or greater with 70 percent 
or greater outside air, will have significant positive impact on energy 
efficiency in heating ventilation and air-conditioning systems with 
high outside air requirements. However, the number of buildings that 
have these systems and that are exempted is significant.
    Requirements have also been added that condenser heat recovery be 
used to provide heating of service hot water for buildings with a 
combination of continuous operation, high water heating loads (greater 
than 1,000,000 Btu per hour) and high cooling loads (approximately 400 
tons). Primary examples are large hotel facilities. These requirements 
significantly increase efficiency, but in a relatively small percentage 
of buildings.
11. Completion Requirements
    Both editions have requirements for testing and balancing of 
heating ventilation and air-conditioning equipment. The 1999 edition 
requires a written balancing report for zones more than 5,000 square 
feet in area, as well as requires the ability to measure differential 
pressure across pumps greater than 10 horsepower in size. For buildings 
larger than 50,000 square feet conditioned area, detailed commissioning 
instructions for heating ventilation and air-conditioning systems are 
required to be provided by the designer in plans and specifications. An 
exception to this requirement is made for warehouses and semi heated 
spaces. The more detailed and extensive documentation requirements have 
the potential to provide long-term energy efficiency beyond what would 
be expected under the minimum completion requirements of the 1989 
edition.
12. Simultaneous Heating and Cooling Controls
    The 1989 and 1999 editions have essentially identical text 
requiring that zone thermostatic and humidistatic controls shall be 
capable of operating the supply of heating and cooling energy in 
sequence to prevent reheating, recooling, or mixing of previously 
heated and cooled air, or other simultaneous operation of heating and 
cooling systems in the same zone. Similarly, exceptions are provided 
for both editions regarding: (1) Zones with special pressurization or 
cross-contamination requirements; (2) zones where at least 75 percent 
of the reheat energy is provided from a site-recovered or site-solar 
source; and (3) where the reheated volume of supply air to a zone is no 
greater than the maximum of several defined limits. However, the 1999 
standard provides much more detail regarding the possible 
characterization of the circumstances under which these exceptions 
would apply. In the third category, the 1999 edition changes the 
stipulations to limit the use of most of these maximum-reheated-air 
exceptions. These changes should result in a reduction in building 
energy use for many common multi-zone heating ventilation and air-
conditioning system designs.
13. Economizer Controls
    The 1999 edition requires economizers in fewer locations than the 
1989 edition, but requires them in the locations of the country where 
they are expected to be most beneficial. The 1989 edition requires 
economizers on 7.5 ton or larger equipment in climates where 
economizers are required. The 1999 edition uses a sliding scale of 
economizer requirements. These requirements depend on climate and 
system size. They range from 65,000 Btu per hour equipment in climates 
where economizers are most effective to 135,000 Btu per hour where 
economizers are least effective. In addition, the 1999 edition requires 
air economizers to be capable of providing 100 percent of the design 
supply air quantity, versus only 85 percent in the 1989 edition. In 
addition, the 1999 edition specifies: (1) Allowed economizer control 
types to maximize economizer savings in specific climates, (2) leakage 
rates for outside air dampers, and (3) that economizer dampers in 
multi-zone systems be capable of being sequenced with the mechanical 
cooling equipment and not be controlled by only mixed air temperature. 
In general, the 1999 edition attempts to provide more economizer 
savings where economizers are most beneficial.
14. Fan System Design Criteria
    Both editions will result in similar fan power efficiencies. 
However, the 1999 edition requires the efficiencies be included on 
motor nameplates, in order to make them more easily inspected. In 
addition, the 1999 edition places these requirements on fan motors of 
five horsepower and above, whereas the 1989 edition places requirements 
on

[[Page 46483]]

motors that are ten horsepower and above. The 1999 edition also has 
more stringent unloading requirements for variable air volume fans. The 
1999 edition places those requirements on variable air volume systems 
of 30 horsepower and above, as compared to variable air volume systems 
of 75 horsepower and above, as specified in the 1989 edition. Both the 
constant volume and variable volume fan power requirements will be 
extended to far more system types in the 1999 edition. Overall, there 
is expected to be a reduction in allowed fan power use in the 1999 
edition, particularly for multi-zone systems.
15. Pumping System Design
    Both editions require that pumping systems designed for variable 
flow be designed to allow flow variation down to 50 percent of design 
flow rates. The 1999 edition also has a requirement that, for systems 
with more than 100 feet of pumping head and motors greater than 50 
horsepower power, consumption at 50 percent flow, be no more than 30 
percent of design flow. This will effectively require variable speed 
pump drives on these large pumping systems. Exceptions are made for 
pumps less than 75 horsepower where reduction of flow would be below 
the minimum flow requirements for heating ventilation and air-
conditioning equipment and for systems that include no more than three 
control valves. Significant energy savings will result from application 
of the 1999 edition in larger pumping systems due to these part-load 
performance requirements.
16. Temperature Reset Controls
    The 1989 edition requires system temperature reset controls on both 
multi-zone air systems and large, non-variable-flow hedonic systems. 
These controls shall be capable of providing a reset of at least 25 
percent of the design supply to room air temperature difference, with 
some exceptions, most notably for low zone flow rates or for systems 
not capable of providing reheat. The primary purpose of this 
requirement is to reduce reheat in air systems. Supply water 
temperatures must also be capable of a reset equivalent to 25 percent 
of the design supply-to-return water temperature difference. This 
requirement does not apply to hydronic systems that can provide a 50 
percent reduction in system flow, or are less than 600,000 Btu per hour 
in capacity. Nor does it apply to reset controls that would cause 
improper operation of heating, cooling, humidification, or 
dehumidification systems.
    The 1999 edition requires reset on chilled and hot water 
temperature controls used for heating ventilation and air-conditioning 
systems more than 300,000 Btu per hour design capacity. Direct energy 
savings are expected from the reset of the supply water temperature 
from chiller and boiler, and the air supply temperatures in the system 
are assumed to follow the water temperature reset. An exception is made 
for hydronic systems that use variable flow to reduce pumping energy, 
or for systems where reset would cause improper operation of heating, 
cooling, humidification or dehumidification systems. Overall, there is 
little net change in the reset requirements for hydronic systems other 
than the 1999 edition applying them to more systems.
    The 1999 edition removes the air supply reset requirements, while 
directly addressing simultaneous heating and cooling. This is addressed 
by better limiting the amount of air reheated or recooled and is set 
forth in a new section of the standard (see Simultaneous Heating and 
Cooling Controls above). Some minimal degradation in efficiency is 
expected from removal of the supply air reset requirements, but this is 
likely to be mitigated by the increase in efficiency from requiring 
reset on smaller hydronic systems.
17. Hot Gas Bypass Restriction
    The 1999 edition introduces a new requirement that restricts the 
use of hot gas bypass in cooling equipment unless the equipment is 
designed with multiple steps of unloading. In the latter case, hot gas 
bypass is allowed, but maximum hot gas bypass levels are specified as a 
fraction of total capacity for different sizes of cooling equipment. 
This requirement will provide an improvement in part-load performance 
for cooling equipment, where manufacturers are not already 
incorporating multiple steps of unloading.
18. Heating Ventilation and Air-Conditioning Equipment
    The 1999 edition provides updated equipment efficiency requirements 
with an effective date of October 29, 2001. Tables 6.2.1A-6.2.1G of the 
1999 edition show the existing 1989 edition's heating ventilation and 
air-conditioning equipment efficiency requirements (shown in the 
``minimum efficiency'' column) with the 1999 edition's update 
requirements shown in the ``Efficiency as of October 29, 2001'' column 
in each table across heating and cooling product categories. Where the 
1999 edition has equipment efficiency requirements but the 1989 edition 
does not (as is the case with absorption and heat rejection equipment 
for example) increased energy efficiency occurs unless the requirements 
are set at or below common practice. In these cases, we used ASHRAE's 
assessment of the minimum performance of the equipment used in common 
practice as a baseline. A summary of the shipped capacity weighted 
efficiency improvements across generic product categories is shown in 
Table 14.

   Table 14.--Shipped Capacity Weighted Efficiency Improvement Across
 Generic Product Categories, Including Equipment Shipments to Commercial
          Buildings Covered by Federal Manufacturing Standards
------------------------------------------------------------------------
                                                         Estimated full
                                                        load efficiency
                  Equipment category                    improvement (in
                                                            percent)
------------------------------------------------------------------------
Unitary Air Conditioners and Condensing Units........                  7
Unitary and Applied Heat Pumps.......................                9.2
Electrically Operated Water Chillers.................               16.8
Absorption Chillers..................................               5.2+
Packaged Terminal Air Conditioners and Heat Pumps....               22.4
Room Air Conditioners................................               10.1
Furnaces, Duct Furnaces, Unit Heaters................                 0+
Boilers..............................................                  0
------------------------------------------------------------------------

    The absorption chillers 5.2 percent estimated full load efficiency 
improvement is based on double effect chillers. The 1989 edition had no 
efficiency requirement for absorption chiller equipment. Based on an 
industry derived market baseline for double effect chillers provided 
during the development of the 1999 edition, the 1989 edition's 
performance coefficient is 0.95. Therefore, selection of the 1999 
edition's coefficient of performance of 1.0 will provide improved 
efficiency. Improvements of up to 25 percent above market minimums are 
estimated for single effect equipment.
    The full load efficiency improvement in room air-conditioners in 
the 1999 edition were adopted from the Department's manufacturing 
standard requirements, effective October 1, 2000 (10 CFR 430). These 
efficiency improvements cannot be attributed to the improved 
requirements of the 1999 edition.
    For furnaces, duct furnaces, and unit heaters, changes were made to 
test procedures and efficiency descriptors for unit heaters, but no net 
change was

[[Page 46484]]

made in efficiency in the 1999 edition. Improved prescriptive 
requirements in the 1999 edition for warm-air furnaces such as 
requirements for intermittent ignition or interrupted device and jacket 
loss limits, will improve annual efficiency.
    For boilers, the full load thermal efficiency descriptor was 
improved in the 1999 edition, but not the boiler efficiency 
requirements. The 1999 edition's requirements for thermal efficiency 
will remove some boilers from the market that currently meet the single 
80 percent combustion efficiency requirement in the 1989 edition, and 
have thermal efficiencies of less than 75 percent. This is particularly 
true of steam boilers.
    In addition to providing updated efficiency requirements for most 
commercial equipment, the 1999 edition subdivides several of the 
original 1989 edition product categories and adds new efficiency 
requirements for heat rejection equipment that were not covered under 
the 1989 edition. The 1999 edition provides coefficient of performance 
and integrated part-load value requirements for centrifugal chillers 
operating at other than nominal test conditions. It also expresses 
efficiency requirements, for boilers less than or equal to 2.5 million 
Btu per hour input rating, using true thermal efficiency, as opposed to 
combustion efficiency requirements in the 1989 edition. The 1999 
edition provides separate efficiency requirements for packaged terminal 
air conditioner and packaged terminal heat pump equipment. The 1999 
edition also updates efficiency requirements to reflect changing test 
procedures and mandates the use of either intermittent or interrupted 
ignition devices and power venting or flue dampers on forced air 
furnaces. Finally, the 1999 edition restricts jacket losses on gas and 
electric furnaces located outside the conditioned space.
    The 1999 edition provides significant improvement to cooling 
equipment efficiencies, and minor increases in average oil or gas space 
heating equipment efficiency due to a change in either efficiency 
designator or shell loss requirements. It also provides for a moderate 
increase in heat pump heating side efficiency. All of these 
requirements (except for room air-conditioners) will improve the 
general efficiency of commercial space conditioning products beyond 
that required in the 1989 edition and will thus contribute to energy 
savings with the 1999 edition.
19. Service Water Heating Equipment Efficiency
    The 1999 edition sets service water heating (SWH) equipment 
efficiencies for gas and oil fired equipment at, or moderately higher 
than, the 1989 edition levels. It improves thermal efficiencies from 
two to three percentage points for gas water heaters with integral 
storage, and improves thermal efficiencies one percent for oil fired 
instantaneous water heaters with integral storage, as well as for the 
similarly defined category of ``hot water supply boiler.''
    For the 1999 edition, the general form of the equations for standby 
loss for oil and gas water heaters were slightly modified and rewritten 
to include a fuel input rating variable and the definition of the 
volume in the equation. In the 1989 edition, the standby loss was 
purely a function of volume. With the modification in the 1999 edition 
of the standby loss equation, standby loss is now a function of both 
volume and input rating. For gas and oil water heaters, the 
stringencies of each standard are roughly the same within each of the 
individual product categories. This allows somewhat more standby loss 
for large input rating products and allows somewhat less standby loss 
for smaller input rating products. Without very detailed information 
about the shipped quantity of products within a size category, it is 
unknown whether there is a net change in efficiency. For electric water 
heaters greater than 12 kilowatt input, the 1999 edition does appear to 
allow marginally greater standby loss, as the formula is based on rated 
as opposed to measured volume. This allows a ten percent variation 
between the rated and measured volume. However, since this product is 
covered by a Federal national manufacturing standard that is more 
stringent than the requirements of the 1999 edition and the federal 
standard preempts state or local regulation, the reduced stringency in 
the 1999 will not reduce energy efficiency.
20. Service Water Heating Controls
    Both the 1989 and 1999 edition have requirements for a minimum 
service hot water temperature control capability set point, as well as 
a maximum control temperature requirement for public restrooms of 110 
degrees Fahrenheit. Since these are only capability and not set point 
requirements, no change in net building energy use is expected or 
assured. The 1989 edition also has a requirement that booster heaters 
be installed where outlet temperatures of more than 120 degrees 
Fahrenheit were required, which is absent in the 1999 edition. The 
energy impact of dropping this requirement is highly dependent on the 
fuel source used by the booster heater. Generally, a slight increase in 
site energy use in specific applications might be expected, however, 
there may also be a corollary reduction in source energy use occurring 
from the reduced use of electric booster heaters (a cheap first cost 
alternative to meeting the 1989 edition requirement). The net impact on 
hot water energy use is expected to be minimal.

D. Energy Cost Budget

    For both editions, the Energy Cost Budget section provides a whole-
building tradeoff methodology to allow innovative or unique buildings 
to comply with the standard. The Energy Cost Budget section requires 
the designer to simulate both a baseline building that complies with 
the standard and the actual design being proposed. The design building 
is not allowed to have a greater energy cost than the baseline building 
that complies with the standard. Neither edition of the standard allows 
designs to exceed the base standard, and as such, the stringency of the 
Energy Cost Budget method in each edition is roughly equivalent to the 
stringency that would be achieved if the building complied with the 
prescriptive requirements of the respective editions of the standard.

E. Conclusion About Detailed Textual Analysis

    Our assessment of seven areas of change in the Lighting and Power 
sections of the two editions leads us to conclude that there will be a 
net positive increase of efficiency in commercial buildings from these 
revisions. Conversely, our assessment of the eleven areas of change in 
the Envelope section of the two editions leads us to conclude that 
there will be a net decrease in efficiency of commercial buildings due 
to these changes. Finally, our review of the 22 areas of change in the 
Mechanical Equipment and Systems sections of the two editions leads us 
to conclude that these revisions will produce a net positive increase 
in the efficiency of commercial buildings.
    We therefore conclude from our detailed textual analysis that there 
will be a modest net gain from the changes.

IV. Filing Certification Statements with DOE

A. Review and Update

    On the basis of today's DOE determination, each State is required 
to

[[Page 46485]]

review and update the provisions of its commercial building code to 
meet or exceed the provisions of the 1999 edition for any ``building'' 
within the meaning of Section 303(2) of the Energy Conservation and 
Production Act, as amended. This action must be taken not later than 
two years from the date of today's notice, unless an extension is 
provided. Section 304(b)(2)(B)(i) and (c).
    The Department recognizes that some States do not have a State 
commercial building code or have a code that does not apply to all 
commercial buildings. If local building codes regulate commercial 
building design and construction rather than a State code, the State 
must provide for review and update of those local codes to meet or 
exceed the 1999 edition. States may base their certifications on 
reasonable actions by units of general purpose local government. Each 
such State must still review the information obtained from the local 
governments and gather any additional data and testimony for its own 
certification.
    States should be aware that the Department considers high-rise 
(greater than three stories) multi-family residential buildings and 
hotel, motel, and other transient residential building types of any 
height as commercial buildings for energy code purposes. Consequently, 
commercial buildings, for the purposes of certification, would include 
high-rise (greater than three stories) multi-family residential 
buildings and hotel, motel, and other transient residential building 
types of any height.

B. Certification

    Section 304(b) of ECPA requires each State to certify to the 
Secretary of Energy that it has reviewed and updated the provisions of 
its commercial building code regarding energy efficiency to meet or 
exceed the 1999 edition. The certification must include a demonstration 
that the provisions of its commercial building energy code regarding 
energy efficiency, meet or exceed Standard 90-1999 for any ``building'' 
within the meaning of Section 303(2) of the Energy Conservation and 
Production Act, as amended. If a State intends to certify that its 
commercial building code already meets or exceeds the requirements of 
the 1999 edition, it would be appropriate for the State to provide an 
explanation of the basis for this certification, e.g., the 1999 edition 
is incorporated by reference in the State's building code regulations. 
The Department believes that it would be appropriate for the chief 
executive of the State (e.g., the Governor) to designate a State 
official, such as the Director of the State energy office, State code 
commission, utility commission, or equivalent State agency having 
primary responsibility for commercial building codes, to provide the 
certification to the Secretary. Such a designated State official could 
also provide the certifications regarding the codes of units of general 
purpose local government based on information provided by responsible 
local officials.

C. Request for Extensions

    Section 304(c) of ECPA requires that the Secretary permit an 
extension of the deadline for complying with the certification 
requirements described above if a State can demonstrate that it has 
made a good faith effort to comply with such requirements and that it 
has made significant progress toward meeting its certification 
obligations. Such demonstrations could include one or more of the 
following: (1) A plan for response to the requirements stated in 
section 304; or (2) a statement that the State has appropriated or 
requested funds (within State funding procedures) to implement a plan 
that would respond to the requirements of section 304.

D. Submittals

    When submitting any certification documents in response to this 
notice, the Department requests that the original documents be 
accompanied by one copy of the same.

    Issued in Washington, DC, on July 8, 2002.
David K. Garman,
Assistant Secretary for Energy Efficiency and Renewable Energy.

Appendix A. Description of Proposed Analysis

    At the February workshop we explained that the proposed analysis 
would provide qualitative comparisons of the stringencies between 
the two editions of Standard 90.1 in: (1) The scope of the standard; 
(2) the building envelope requirements; (3) the building lighting 
requirements; (4) the building mechanical equipment requirements; 
and (5) the paths to compliance.
    We stated that the proposed emphasis of the qualitative 
comparison would differ between the envelope, lighting, and 
mechanical sections. In the building envelope section, the 
comparison would focus on the impact of the different building 
envelope requirements on the building heating and cooling loads for 
different building types and climates. The envelope comparison would 
examine requirements for all envelope components, including roofs, 
walls, floors, and fenestration as well as explore variations in 
construction types and in the window-to-wall ratio.
    In the lighting requirements comparison, we explained that the 
proposed focus would be primarily on the impact the different 
lighting requirements have on lighting energy use, as well as on 
building loads. The comparison would look separately at the whole 
building and space-by-space lighting requirements in a variety of 
commercial building types, as well as examine the effect of any 
``additional lighting power allowances.''
    We proposed that the mechanical requirements comparison be 
divided into comparisons of equipment efficiency requirements and 
system design requirements. We explained that the system design 
requirements affect both the system efficiency and system load 
impacts, and may have direct energy impacts as well. We also 
proposed that tables of relative stringency and estimated positive 
or negative national energy impact be prepared based on practical 
application of the system design requirements in each standard.
    We explained that each standard has multiple ways to demonstrate 
compliance. We proposed to enumerate the multiple paths to 
compliance, but did not propose to perform a detailed comparison of 
the relative stringency of alternate paths internal to a single 
standard or between standards. We explained that the large quantity 
of variables among the alternative compliance paths would make such 
analysis prohibitive to undertake. Further, we explained that we 
knew of no data on which to base the selection of representative 
requirements for such an analysis. Assignment of requirements would 
be arbitrary. Rather we proposed to focus on what we believed is the 
most common approach to using the standard in question for 
particular building types.
    Addressing the quantitative analysis, we proposed to base the 
quantitative comparison of energy codes on whole building energy 
simulations of buildings built to each standard. We proposed to 
simulate seven representative building types in 11 representative 
U.S. climates. The simulated buildings would utilize the 15 zone 
building prototypes used in previous DOE building research, and the 
energy use intensities for each zone from the simulations would be 
scaled to correctly reflect variations in characteristic building 
sizes and shapes for each representative building type. Energy Use 
Intensities (EUIs) developed for each representative building type 
would be weighted by total national square footage in each 
representative building category to provide an estimate of the 
national energy savings.
    We noted that only changes to requirements for new buildings 
would be considered in this quantitative analysis.

Appendix B. Description of the Quantitative Analysis

    The analysis methodology is briefly described below. This is 
followed by a description of the input assumptions.

I. Analysis Methodology

    To determine the aggregate impact of changes to the envelope, 
lighting, and mechanical sections of 90.1, a series of building 
simulations were made using the BLAST (Building Loads Analysis and 
System Thermodynamics) building simulation

[[Page 46486]]

software. Seven building types, shown in Table 15, were used in the 
analysis. These seven building types used represent approximately 80 
percent of commercial building energy consumption, according to the 
Energy Information Administration's 1995 Commercial Building Energy 
Consumption Survey (CBECS95) data. (The Office building type 
includes Outpatient Health Care at 76.6 thousand Btu per year.)

 Table 15.--Energy Consumption by Principal Building Activity (Trillion
                                  Btu)
------------------------------------------------------------------------
                                           Annual energy    Percent of
        Building types simulated                use            total
------------------------------------------------------------------------
Office..................................           1,095            20.6
Mercantile and Service..................             973            18.3
Education...............................             614            11.5
Lodging.................................             461             8.7
Public Assembly.........................             449             8.4
Food Service............................             332             6.2
Warehouse and Storage...................             325             6.1
                                         -------------------------------
    Total for above Categories..........           4,249  ..............
                                         -------------------------------
    Total for all commercial buildings..           5,323            79.8
------------------------------------------------------------------------

    Construction variation within each building category was 
simulated using four different window to wall area ratios, both mass 
(such as dense masonry) and light frame wall construction types, and 
gas and electric heating fuel types. Two scenarios of economizer 
usage were simulated in each climate to account for the variation of 
economizer usage requirements in combination with equipment size. 
The buildings were simulated in 11 different climate locations 
(Table 16). The climate locations were chosen based on statistical 
cluster analysis of 234 Typical Mean Year weather data tapes and 
were chosen to be representative of the variation in climate found 
in the U.S. Several of the more significant climate parameters are 
shown in Table 16. These include, Heating Degree Days, base 65 
degrees Fahrenheit (HDD 65); Vertical Solar radiation, in the North 
(VSN), East/West (VSEW), and South (VSS) orientations; Cooling 
Degree Day, base 50 degrees Fahrenheit (CDD 50); minimum recorded 
outdoor temperatures for 99.6 percent of the time for heating design 
calculations; maximum recorded Dry Bulb (DB) outdoor temperatures 
exceeded 1 percent of the time for cooling design calculations; and 
maximum recorded Wet Bulb (WB) outdoor temperatures exceeded one 
percent of the time, also for cooling design calculations.

                                                           Table 16.--Climates Locations Used
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                  Cooling      Cooling
                    Location                         HDD 65        VSN          VSEW         VSS         CDD 50      Heating     design (1%   design 1%
                                                                                                                   design 99.6      DB)          WB)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Denver, CO......................................         6083          428          971         1321         2611           -3           90           59
Detroit, MI.....................................         5997          390          676          858         3199            0           87           72
Fresno, CA......................................         2700          459         1029         1199         5070           30          101           70
Knoxville, TN...................................         3818          446          762          898         4455           13           90           74
Los Angeles, CA.................................         1494          482          962         1146         4456           43           81           64
Minneapolis, MN.................................         8060          380          709          972         2751          -16           88           71
Orlando, FL.....................................          532          511          881          974         8288           37           93           76
Phoenix, AZ.....................................         1382          488         1116         1310         7830           34          108           70
Providence, RI..................................         6022          393          677          874         2756            5           86           71
Seattle, WA.....................................         5281          350          621          828         1683           23           81           64
Shreveport, LA..................................         2265          484          843          954         6022           22           95           77
Tampa, FL.......................................          575          518          890          974         7985           36           91           77
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In addition to simulating buildings that complied with the 1989 
and 1999 editions, the changes in envelope, lighting and mechanical 
requirements were each separately simulated, without changing the 
1989 edition's requirements for the other components. Then, because 
the lighting and envelope requirements impact each other, 
particularly in the 1989 edition, the combined lighting and envelope 
requirement differences were analyzed, again without changing the 
1989 edition's requirements for the other components. Calculating 
the difference between this combination and all 1999 edition 
requirements allowed an assessment of the impact of the mechanical 
changes after adjusting for this thermal load shift. In all, six 
separate sets of requirement changes were simulated.
    In total, 2464 simulations were performed for each set of 
requirement changes. A prototypical 48,000 ft2, 15-zone, 
slab-on-grade building was used for all the simulations. Simulation 
results for this prototypical building size were then scaled to 
reflect aggregate energy use in buildings across a wide range of 
sizes and shapes using Commercial Building Energy Consumption Survey 
building data. Single zone air-conditioning and heating systems were 
assumed in the building model to permit this scaling. This 
simplification should result in a lower-bound estimate of energy 
savings with the standard as explained in mechanical system 
characterization below.

II. Simulation Input Characterization

A. Envelope

    The building envelope characteristics examined in the analysis 
were the opaque wall and roof U-factors, the fenestration U-factors, 
either the fenestration Shading Coefficient requirements (in the 
1989 edition) or Solar Heat Gain Coefficient requirements (in the 
1999 edition), and the effective slab U-factors for slab on grade 
construction. These characteristics were determined for each set of 
requirement changes, building type, and climate combination 
simulated.
    The 1989 edition's envelope requirements simulated were based on 
the 1989 edition's Alternate Component Packages (ACP) tables. These 
tables represent the prescriptive compliance path for the 1989 
edition's envelope requirements. Because the 1989

[[Page 46487]]

edition's requirements do not necessarily reflect the performance of 
typical building assemblies, the actual U-factors used in the 
simulations were chosen to reflect the U-factors of real building 
assemblies which best approach, without being less stringent than, 
the U-value requirements of the standard. This is expected to be 
more representative of the real envelope performance resulting from 
application of the 1989 edition. Note that by being more stringent 
than the U-factor requirements, this procedure provides a 
conservative estimate of the envelope energy savings.
    In addition, the 1989 edition's ACP tables represent more 
stringent envelope requirements than that specified for most 
climates or buildings, using these equations outlined in Chapter 8 
of the 1989 edition. The equations are embodied in the ENVSTD, 
version 2.4, software. For this reason, the use of the ACP tables as 
the basis for the 1989 edition's envelope provides a lower boundary 
to the estimate of energy savings from the building envelope 
requirements.

B. Lighting

    The lighting power density requirements were developed from the 
whole building lighting requirements for both the 1989 and 1999 
editions, for comparable building types, where available. The 1999 
edition provides single value whole building lighting power density 
values for 31 different building types. The 1989 edition provides 
whole building lighting power density values for only 11 different 
building types. However, it provides different lighting power 
densities for six different building size categories within each 
building type. In neither case do the whole building lighting power 
density values correspond perfectly to the building types simulated. 
The following procedure was used to develop whole building lighting 
numbers for each of these categories.

1. Lighting Power--1989 Edition

    For office and warehouse building types, where there is a direct 
match with the 1989 standard whole building lighting power 
categories, the lighting power density was estimated by weighting 
the whole lighting power density across the six building size 
categories by the fraction of each building type's floor space in 
each size category using CBECS95 data.
    In the case of Food Service and Education, the 1989 edition 
provides lighting power density values for subcategories of these 
building types. Food Service is composed of Fast Food/Cafeteria and 
Leisure Dining/Bar subcategories, Education is composed of 
Preschool/Elementary, Jr. High/High School, and Technical/Vocational 
subcategories. In these cases, first the lighting power densities 
for the different building sub types were averaged together for each 
building area category. Then, a weighting of these new lighting 
power densities by building size category was made, using CBEC's 
data for Food Service or Education building types, as appropriate.
    In the case of retail type buildings, the 1989 edition has three 
basic retail building subcategories, Retail, ``Mall Concourse, and 
``Service. Commercial Building Energy Consumption Survey floor area 
data is categorized as Enclosed Shopping Center/Mall, Retail (except 
Mall), Service (except Food), and Strip Shopping. To make a 
realistic weighting by retail type the following allocation of 
Commercial Building Energy Consumption Survey retail type floor area 
was made.

         Table 17.--Allocation of CBECS95 Retail Type Floor Area
------------------------------------------------------------------------
                                                Allocation of CBECS95
 Retail building categories--1989 edition   building category floor area
------------------------------------------------------------------------
Retail....................................  Retail (except Mall) plus
                                             Strip Shopping plus half of
                                             Enclosed Shopping/Mall.
Mall Concourse............................  Half of Enclosed Shopping/
                                             Mall.
Service...................................  Service (except Food).
------------------------------------------------------------------------

Then a weighted average of the allowed lighting power densities was 
constructed, using the 1989 edition's lighting power density values 
and the CBECS95 floor area data for each building type and size 
category.
    For Lodging and Public Assembly building types, the 1989 edition 
has no direct match in the whole building lighting power density 
tables. For a comparison of these building types, the 1989 edition's 
whole building lighting power density values were developed by 
applying the appropriate 1989 edition's space-type lighting power 
density values (with appropriate Area Factor adjustments) to the 
building specific space type square footage data used in the 
development of the 1999 edition lighting power densities. The 1989 
edition building specific space type data models the actual 
weighting of space type square footage, within a specific building 
type, based on actual current U.S. construction data. The lighting 
power density value for the Lodging category is made up of the 
average of the whole building lighting power densities constructed 
for the 1999 edition's building categories: Dormitory, Hotel, and 
Motel. The lighting power density value for the Public Assembly 
categories is similarly made up of the average 1999 edition's whole 
building lighting power density values for Convention Center, Motion 
Picture Theater, Performing Arts Theater, Town Hall, Sports Arena, 
Museum, and Gymnasium.

2. Lighting Power--1999 Edition

    The 1999 edition provides single value, whole building, lighting 
power density requirements for Office, Retail, Education, and 
Warehouse buildings, and these requirements were used in the 
simulations. The 1999 edition does not provide single lighting power 
density values for Food Service, Lodging, or Public Assembly 
buildings. For these cases, the average whole building lighting 
power density requirements, for building types falling in each 
category, was taken to form a single lighting power density 
requirement. In these cases, the same specific building types used 
to develop the 1989 edition's lighting power density values were 
used to derive the 1999 edition's lighting power densities for 
Lodging and Public Assembly building types. The 1999 edition's Food 
Service value was derived as the average of the 1999 edition's three 
whole building food service building type values.
    Table 18 shows a comparison of Whole Building lighting 
requirements under both editions.

                    Table 18.--Lighting Power Density
                              [Watts/ft\2\]
------------------------------------------------------------------------
           Building type               1989 edition       1999 edition
------------------------------------------------------------------------
Education.........................               1.79               1.50
Food Service......................               1.62               1.73
Lodging...........................               1.53               1.73
Offices...........................               1.63               1.30
Public Assembly...................               1.72               1.53
Retail............................               2.36               1.90
Warehouse/Storage.................               0.53               1.20
------------------------------------------------------------------------

C. Mechanical Equipment

    Single zone cooling and heating systems were used in the 
analysis. The choice of single zone system in the analysis is 
expected to provide a lower boundary to our estimate of cooling 
energy savings. First, this is because the improvement in the 1999 
edition's average efficiency requirements, for single zone cooling 
systems (typically unitary equipment), is relatively small compared 
to that for typical central system cooling equipment (typically 
water chillers). This is more obvious when one realizes that 
shipments of all products to commercial buildings includes 
residential type cooling

[[Page 46488]]

products shipped to small commercial buildings. Additionally, 
modeling single zone systems does not take into account the fact 
that the 1999 edition has introduced requirements for central system 
heat rejection equipment, where none existed in the 1989 edition. 
There is relatively little improvement in heating equipment 
efficiency requirements, in the 1999 edition, for equipment used in 
single zone systems (typically furnaces), or central systems 
(typically boilers). The impact of the 1999 edition on heating 
energy use will typically be determined principally by changes in 
heating loads rather than heating equipment efficiency.

1. Cooling Equipment

    Cooling equipment efficiencies were developed by weighting the 
energy efficiency rating for each of 20 categories of single zone 
cooling equipment in the standard, by an estimate of shipped cooling 
capacity for each category. The primary source of shipping data was 
1998 U.S. Census Data. In the case of the less than 65,000 Btu per 
hour unitary air source heat pumps and air conditioners, this census 
data was augmented by our interpretation of Air-Conditioning and 
Refrigeration Institute and Lawrence Berkeley National Laboratory 
data on single phase air-conditioners and heat pumps shipped to 
commercial buildings. Using the weighting information and equipment 
efficiencies in each edition, the average unitary equipment 
efficiency requirement for commercial buildings increased 7.5 
percent, from an average energy efficiency ratio of from 9.28 to 
9.98. This improvement was simulated for all building types except 
Lodging. For Lodging, it was assumed that the majority of single 
zone cooling equipment would be packaged terminal equipment. The 
average efficiency requirement for packaged terminal equipment 
increased 22 percent, from 8.4 to 10.28, based on a shipped capacity 
weighting. These efficiencies were used in the Lodging simulations 
for the respective Standard levels.

2. Space Heating Equipment

    No change in heating equipment combustion efficiency is required 
in the 1999 edition. However, for commercial furnaces, a reduction 
in the loss through the equipment casing from 1.5 percent to 0.75 
percent was modeled to reflect differences in the requirements in 
the two editions. No change in furnace casing losses was assumed 
where electric resistance heat was assumed.

3. Economizers

    For each building type, simulations were made both assuming 
economizer operation and not assuming economizer operation. Based on 
the economizer requirements in each edition and the available 
cooling equipment shipment data, shipped cooling capacity weights 
were developed for systems requiring economizer usage in each 
climate.

4. Service Water Heating Equipment

    Service water heating equipment efficiencies increased from 78 
percent to 80 percent for most tank-type gas fired water heaters. 
This was reflected in the input assumptions. We did not account for 
shipments of residential size water heating equipment (regulated by 
manufacturing standards under Subpart C of 10 CFR 430) to commercial 
buildings. While these units may be used in some commercial 
buildings, increased efficiencies are the result of regulatory 
actions under 10 CFR 430, not Standard 90.1. Nor did we account for 
the use of tankless instantaneous water heaters in commercial 
buildings. Correctly accounting for shipped capacity of both the 
residential size and tankless equipment to commercial buildings 
would reduce the average efficiency improvement somewhat, but 
accurate shipment data to commercial buildings is largely 
unavailable.
    No change in water heater standby loss efficiencies was modeled. 
For fossil fuel fired equipment, the standby loss efficiencies 
within a given size category are essentially the same. While a 
different formulation of the standby loss equations was used in the 
1999 edition, there are both standby loss increases and decreases in 
any given product category. We are unaware of a data base that 
categorizes this data to permit accurate estimation of a net result. 
For electric water heaters, there appears to be a reduction in 
standby loss efficiency in the 1999 edition. However, the Energy 
Policy and Conservation Act, as amended, does not permit the 
manufacture or sale of these lower efficiency products. Therefore, 
there is no predicted impact on actual buildings.

D. Aggregation of Results

    Aggregation to a national estimate of energy use is based on 
energy use intensities (EUI) developed from simulations, under each 
edition. Aggregation of energy use intensity from the simulations 
was done as follows: (1) Extract zone-based energy use intensities 
from simulations; (2) aggregate results by required economizer usage 
in each climate; (3) map simulation results by climate to 11 
geographical areas (augmented census divisions); (4) scale 
simulation results to existing building stock floor area by building 
type and census region; (5) weight results for frame and mass wall 
construction by appropriate building type and census region weights 
for these types of construction; (6) weight results for heating fuel 
by augmented census division weights for electric resistance heating 
usage in commercial buildings (Commercial Building Energy 
Consumption Survey data); (7) convert energy use intensities by fuel 
type to site energy, source energy, and energy cost intensities, by 
building type, and augmented census division; (8) weight energy use 
intensity results by building construction floor area estimates, by 
building type and in each augmented census division. The building 
construction data was derived from the Energy Information 
Administration's National Energy Modeling System data sets.

[FR Doc. 02-17637 Filed 7-12-02; 8:45 am]
BILLING CODE 6450-01-P