Executive Summary
This document provides a comprehensive comparison of Normative Appendix G (Performance Rating Method) between ASHRAE Standard 90.1-2019 and ASHRAE Standard 90.1-2022. The analysis identifies all changes including new sections, removed sections, renumbered sections, and content modifications.
SECTION 4.2.1.1 - NEW BUILDINGS (Referenced by Appendix G)
This section defines the compliance requirements when using the Performance Rating Method (Appendix G) as an alternative compliance path.
Section 4.2.1.1 Comparison
Compliance Path Options
2019 Compliance Options:
New buildings shall comply with Sections 4.2.2 through 4.2.5 and either the provisions of:
Section 5, "Building Envelope"; Section 6, "Heating, Ventilating, and Air Conditioning"; Section 7, "Service Water Heating"; Section 8, "Power"; Section 9, "Lighting"; and Section 10, "Other Equipment," or
Section 11, "Energy Cost Budget Method," or
Normative Appendix G, "Performance Rating Method."
2022 Compliance Options:
New buildings shall comply with Section 4.2.2 through 4.2.5 and either the provisions of:
Sections 5, "Building Envelope"; 6, "Heating, Ventilating, and Air Conditioning"; 7, "Service Water Heating"; 8, "Power"; 9, "Lighting"; 10, "Other Equipment"; and 11, "Additional Efficiency Requirements," or
Section 12, "Energy Cost Budget Method," or
Normative Appendix G, "Performance Rating Method."
Key Change:
Energy Cost Budget Method
Additional Efficiency Requirements (mandatory for prescriptive path)
Where:
PCIt = Performance Cost Index Target
BBUEC = Baseline Building Unregulated Energy Cost
BPF = Building Performance Factor from Table 4.2.1.1
BBREC = Baseline Building Regulated Energy Cost
BBP = Baseline Building Performance
Where (NEW definitions in bold):
PCIt = Performance Cost Index Target
BBUEC = Baseline Building Unregulated Energy Cost
BPF = Building Performance Factor from Table 4.2.1.1
BBREC = Baseline Building Regulated Energy Cost
PRE = PBPnre − PBPpre (NEW)
PBPnre = Proposed building performance without any credit for reduced annual energy costs from on-site renewable energy generation systems (NEW)
PBPpre = Proposed building performance, excluding any renewable energy system in the proposed design and including an on-site renewable energy system that meets but does not exceed the requirements of Section 10.5.1.1 (NEW)
BBP = Baseline Building Performance
Subtracted from numerator
Limits renewable energy credit
Performance without renewables
Performance with prescriptive renewables only
Capped at prescriptive requirement
Prevents over-reliance on renewables
2022 Additional Renewable Energy Compliance Requirement 🟢 NEW
When on-site renewable energy exceeds the prescriptive requirement by more than 5%, the following additional compliance check applies:
This requirement ensures that buildings with large renewable energy systems still achieve meaningful efficiency improvements in building systems and envelope.
BPF Definition Changes
Default for unlisted types
Area-weighted average based on gross floor area
Existing building + addition
Area-weighted average of existing BPF (per 4.2.1.3) and addition BPF
2022 Alterations BPF Modifications 🟢 NEW
Alteration Type
BPF Requirement
Substantial alterations (per Section G3.1.4(a))
Table 4.2.1.1 value × 1.05 (5% relaxation)
Other alterations (per Section G3.3)
BPF = 1.0 (no efficiency improvement required beyond code)
Climate Zone Column Changes
2022 now provides separate BPF values for Climate Zones 0A, 0B, 1A, and 1B instead of combining them.
BPF Value Comparison by Building Type
Climate Zone
2019
2022
Change
Healthcare/Hospital
Climate Zone
2019
2022
Change
Note: Healthcare/Hospital BPF values have increased significantly (relaxed) across all climate zones, with changes ranging from +0.08 to +0.15.
Climate Zone
2019
2022
Change
Note: Hotel/Motel BPF values have increased significantly (relaxed) across all climate zones.
Climate Zone
2019
2022
Change
Climate Zone
2019
2022
Change
Note: School BPF values have increased dramatically (relaxed) across all climate zones, with changes ranging from +0.06 to +0.18.
Climate Zone
2019
2022
Change
Note: Warehouse BPF values have decreased dramatically (more stringent) across all climate zones, with changes ranging from −0.12 to −0.28.
Climate Zone
2019
2022
Change
Climate Zone
2019
2022
Change
Climate Zone
2019
2022
Change
BPF Changes Summary
Building Type
Overall Trend
Range of Change
Interpretation:
Lower BPF = More stringent (building must perform better relative to baseline)
Higher BPF = Less stringent (building can perform closer to baseline)
Key Observations:
Warehouses became much more stringent - BPF values dropped by 0.12 to 0.28, requiring significantly better performance.
Schools, Hotels, and Healthcare became less stringent - BPF values increased by 0.06 to 0.18, reflecting recognition of the challenges in achieving deep efficiency in these building types.
Retail became more stringent - BPF values dropped by up to 0.12 in some climate zones.
Renewable energy credit now capped - The new PRE term and additional compliance check prevent over-reliance on renewable energy to meet compliance targets.
Alterations get BPF relief - Substantial alterations can use BPF × 1.05; other alterations use BPF = 1.0.
Key Structural Changes
1. Major Reorganization
G3.1.2.x (General Baseline HVAC System Requirements) → G3.2.2.x
G3.1.3.x (Baseline Building Envelope) → G3.2.3.x
G3.1.1.x subsections → G3.2.1.x subsections
2. New Section G3.3
Added "Performance Calculations for Alterations (Other Than Substantial Alterations)" with subsections G3.3.1 through G3.3.2.9
3. Table G3.7 Split
The single Table G3.7 in 2019 has been split into Table G3.7-1 and Table G3.7-2 in 2022
4. New Table G3.4-9
Added for Climate Zone 9 building envelope requirements
5. Expanded Simulation Requirements
Section G2.2.4 expanded with detailed subsections G2.2.4.1, G2.2.4.2, G2.2.4.3 for simulation program testing
6. 🟢 NEW Thermal Bridging Requirements
Significant new content in Table G3.1 (Building Envelope): Linear and point thermal bridges per Section 5.5.5 must now be modeled in proposed design; baseline building design explicitly excludes thermal bridges (creating credit opportunity)
Color/Status Legend
Section number changed but content similar
PART 1: SECTION-BY-SECTION COMPARISON
G1 - General Header
Content: Header section only - no substantive change.
2019 Content:
This appendix offers an alternative path for minimum standard compliance in accordance with Section 4.2.1.1 when administered by a building official. It is also provided for those who wish to use this appendix to quantify performance that exceeds the requirements of this standard when administered by a rating authority and not seeking minimum standard compliance in accordance with Section 4.2.1.1. It shall be used for evaluating the performance of all such proposed designs, including alterations and additions to existing buildings, except designs with no mechanical systems. In the case where this appendix is administered solely by a building official to determine compliance with this standard in accordance with Section 4.2.1.1, all references to "rating authority" shall be replaced with "building official."
2022 Content:
This appendix offers an alternative path for minimum standard compliance in accordance with Section 4.2.1.1 when administered by a building official. It is also provided for those who wish to use this appendix to quantify performance that exceeds the requirements of this standard when administered by a rating authority and not seeking minimum standard compliance in accordance with Section 4.2.1.1. It shall be used for evaluating the performance of all such proposed designs, including alterations and additions to existing buildings, except designs with no mechanical systems. In the case where this appendix is administered solely by a building official to determine compliance with this standard in accordance with Section 4.2.1.1, all references to "rating authority" shall be replaced with "building official."
Informative Note: To fully utilize the investment made to create a building energy model during the design process, the methodology described in ASHRAE Standard 209 should be considered.
Change Summary:
Added: Informative Note referencing ASHRAE Standard 209 for building energy modeling methodology
Content: Section header only.
G1.2.1 - Mandatory Provisions
2019 Content:
The proposed building design shall comply with all of the following:
a. Sections 5.2.1, 6.2.1, 7.2.1, 8.2.1, 9.2.1, and 10.2.1.
Interior lighting power shall not exceed the interior lighting power allowance determined using either:
Table G3.7 and the methodology described in Section 9.6.1, or
Table G3.8 and the methodology described in Section 9.5.1.
Energy efficiency levels of installed components and systems that meet or exceed the efficiency levels used to calculate the proposed building performance.
Verification, testing, and commissioning requirements of Section 4.2.5 shall be met.
Proposed building systems, controls, or building envelope documented in Section G1.3(c) that do not have criteria in Sections 5 through 10 shall have verification or testing to document proper installation and operation in accordance with Section 4.2.5.
2022 Content:
The proposed building design shall comply with all of the following:
a. Sections 5.2.1, 6.2.1, 7.2.1, 8.2.1, 9.2.1, and 10.2.1.
Interior lighting power shall not exceed the interior lighting power allowance determined using either:
Tables G3.7-1 and G3.7-2 and the methodology described in Section 9.5.2, or
Table G3.8 and the methodology described in Section 9.5.1.
Energy efficiency levels of installed components and systems shall meet or exceed the efficiency levels used to calculate the proposed building performance.
For new buildings, one of the following shall be met:
The building envelope complies with Section 5.5, "Prescriptive Building Envelope Compliance Path."
Using Section 5.6, "Building Envelope Trade-Off Compliance Path," the proposed envelope performance factor shall not exceed the base envelope performance factor by more than 15% in multifamily residential, hotel/motel, and dormitory building area types. For all other building area types, the limit shall be 7%. For buildings with both residential and nonresidential occupancies, the limit shall be based on the area-weighted average of the gross conditioned floor area.
Verification, testing, and commissioning requirements of Section 4.2.5 shall be met.
Proposed building systems, controls, or building envelope documented in Section G1.3(c) that do not have criteria in Sections 5 through 10 shall have verification or testing to document proper installation and operation in accordance with Section 4.2.5.
Change Summary:
Building envelope compliance requirement for new buildings (Section 5.5 or 5.6 with limits)
2019 Content:
Performance Cost Index = Proposed building performance/Baseline building performance
Both the proposed building performance and the baseline building performance shall include all end-use load components within and associated with the building when calculating the Performance Cost Index.
Exception to G1.2.2: Energy used to recharge or refuel vehicles that are used for off-building site transportation purposes shall not be modeled in the baseline building performance or the proposed building performance.
Informative Note: Neither the proposed building performance nor the baseline building performance are predictions of actual energy consumption or costs for the proposed design after construction...
2022 Content:
Performance Cost Index = Proposed building performance/Baseline building performance
Both the proposed building performance and the baseline building performance shall include all end-use load components within and associated with the property when calculating the Performance Cost Index.
Exception to G1.2.2: Energy used to recharge or refuel vehicles that are used for off-site transportation purposes shall not be modeled in the baseline building performance or the proposed building performance.
Informative Notes:
Neither the proposed building performance nor the baseline building performance are predictions of actual energy consumption or costs for the proposed design after construction...
See Informative Appendix I for using other metrics, including site energy, source energy, and carbon emissions, in conjunction with the Normative Appendix G Performance Rating Method when approved by the rating authority.
Change Summary:
Added second informative note referencing Appendix I for alternative metrics (site energy, source energy, carbon emissions)
G1.3 - Submittals
Content: Section header only.
G1.3.1 - General
Compliance documentation and supplemental information shall be submitted in accordance with Section 4.2.2 of this standard.
G1.3.2 - Application Documentation 🟢 NEW/EXPANDED
2022 Content (New Explicit Section):
The following documentation shall be submitted to the rating authority:
The simulation program used, the version of the simulation program, and the results of the energy analysis, including the calculated values for:
baseline building unregulated energy cost (BBUEC)
baseline building regulated energy cost (BBREC)
building performance factor (BPF)
baseline building performance
proposed building performance
Performance Cost Index (PCI)
Performance Cost Index Target (PCIt)
An overview of the project that includes the number of stories (above and below grade), the typical floor size, the uses in the building, the gross area of each use, and whether each use is conditioned space.
A list of the energy-related features that are included in the design and on which the performance rating is based.
A list showing compliance for the proposed design with all the requirements of Sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4 (mandatory provisions).
A list identifying those aspects of the proposed design that are less stringent than the requirements of Sections 5.5, 6.5, 7.5, and 9.5 (prescriptive provisions).
A list identifying those aspects of the proposed design that are more stringent than the requirements of Sections 5 through 10. (NEW)
A table with a summary by end use of the proposed building performance and baseline building performance, with each end use separated into regulated and unregulated components. (NEW detail)
A site plan showing all adjacent buildings and topography that may shade the proposed building.
Building elevations and floor plans.
A diagram showing the thermal blocks used in the computer simulation.
An explanation of any significant modeling assumptions.
Backup calculations and material to support data inputs.
Reports from the simulation program showing:
a breakdown of energy use by components
the amount of unmet load hours
a description of energy-related features of the budget building design and the proposed design (NEW)
Purchased energy rates used in the simulations.
An explanation of any error messages noted in the simulation program output.
For any exceptional calculation methods employed, document the predicted energy savings.
The reduction in proposed building performance associated with on-site renewable energy.
The version of the software and the link to the website that contains the ASHRAE Standard 140 results for the version used in accordance with Section G2.2.4. (NEW)
Simulation input files for the budget building design and the proposed design shall be made available if requested by the building official. (NEW)
Change Summary:
Formalized as explicit numbered section
Added BBUEC, BBREC, BPF to required calculated values
Added requirement for list of features MORE stringent than prescriptive
Required end-use separation into regulated/unregulated components
Added requirement for ASHRAE Standard 140 results website link
Added requirement for simulation input files upon request
G1.3.3 - Completion Requirements
Completion requirements shall be in compliance with Sections 5.7.3, 6.7.3, 7.7.3, 8.7.3, 9.7.3, and 10.7.3.
G2. SIMULATION GENERAL REQUIREMENTS
The proposed building performance and baseline building performance shall be calculated using the following:
The same simulation program
G2.2 - Simulation Program
The simulation program shall be a computer-based program for the analysis of energy consumption in buildings (a program such as, but not limited to, DOE-2, BLAST, or EnergyPlus).
G2.2.1 - Simulation Program Requirements 🟢 NEW
The simulation program shall be approved by the rating authority and shall, at a minimum, have the ability to explicitly model all of the following:
Hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat setpoints, and HVAC system operation, defined separately for each day of the week and holidays
Ten or more thermal zones
Part-load performance curves for mechanical equipment
Capacity and efficiency correction curves for mechanical heating and cooling equipment
Air-side economizers with integrated control acting in conjunction with mechanical cooling
Baseline building design characteristics specified in Section G3
G2.2.2 - Simulation Program Capabilities
The simulation program shall have the ability to either directly determine the proposed building performance and baseline building performance or produce hourly reports of energy use by energy source that can be postprocessed.
G2.2.3 - Design Load Calculations
The simulation program shall be capable of performing design load calculations to determine required HVAC equipment capacities in accordance with Section 6.4.2.
G2.2.4 - Simulation Program Testing
🟡 MODIFIED (restructured)
2019 Content:
The simulation program shall be tested according to ASHRAE Standard 140, except for Sections 7 and 8 of Standard 140. The test results and modeler reports shall be posted on a publicly available website and shall include the test results of the simulation program along with the results of the other simulation programs included in ASHRAE Standard 140, Annexes B8 and B16. The modeler report in Standard 140, Annex A2, Attachment A2.7 shall be completed for results exceeding the maximum or falling below the minimum of the reference values or for missing results.
Informative Note: There are no pass/fail criteria established by this requirement.
2022 Content:
Simulation Program Testing Requirements (Now a parent section with subsections)
G2.2.4.1 - Testing Requirements 🟢 NEW
2022 Content:
The simulation program shall be tested according to ASHRAE Standard 140, except for Sections 7 and 8 of Standard 140. The required tests shall include:
Building thermal envelope and fabric load tests (Sections 5.2.1, 5.2.2, and 5.2.3)
Ground coupled slab-on-grade analytical verification tests (Section 5.2.4)
Space-cooling equipment performance tests (Section 5.3)
Space-heating equipment performance tests (Section 5.4)
Air-side HVAC equipment analytical verification tests (Section 5.5)
along with the associated reporting (Section 6)
G2.2.4.2 - Test Results Publication 🟢 NEW
2022 Content:
The test results and modeler reports shall be posted on a publicly available website and shall include the test results of the simulation program and input files used for generating the results along with the results of the other simulation programs included in ASHRAE Standard 140, Annexes B8 and B16. The modeler report in Standard 140, Annex A2, Attachment A2.7 shall be completed for results exceeding the maximum or falling below the minimum of the reference values and for omitted results.
Change from 2019:
Added "and input files used for generating the results"
Changed "missing results" to "omitted results"
G2.2.4.3 - Testing Version Requirements 🟢 NEW
2022 Content:
The testing shall be performed for the version of the simulation program used to calculate the proposed building performance and baseline building performance.
G2.3 - Climatic Data
The simulation program shall perform the simulation using hourly values of climatic data, such as temperature, solar radiation, humidity, and wind speed from representative climatic data (e.g., typical meteorological year [TMY] or equivalent)...
G2.4 - Renewable, Recovered, and Purchased Energy 🟢 NEW PARENT
G2.4.1 - On-Site Renewable Energy and Site-Recovered Energy
Site-recovered energy shall not be considered purchased energy and shall be subtracted from the proposed design energy consumption prior to calculating the proposed building performance. On-site renewable energy shall be subtracted from the proposed design energy consumption prior to calculating the proposed building performance, provided that the building owner:
owns the on-site renewable energy system or
has signed a lease agreement for the on-site renewable energy system for at least 15 years or
has signed a contractual agreement to purchase energy generated by the on-site renewable energy system for at least 15 years.
G2.4.2 - Annual Energy Costs
The design energy cost and baseline energy cost shall be determined using either actual rates for purchased energy or state average energy prices published by USDOE's Energy Information Administration (EIA) for commercial building customers...
G2.5 - Exceptional Calculation Methods
When the simulation program does not model a design, material, or device of the proposed design, an exceptional calculation method shall be used as approved by the rating authority...
The simulation model for calculating the proposed and baseline building performance shall be developed in accordance with the requirements in Table G3.1.
G3.1.1 - Scope/Baseline HVAC System Type
G3.1.1 Baseline HVAC System Type and Description
2019 Content:
Contained detailed HVAC system selection criteria including building area types, floor counts, and system assignment rules.
2022 Content:
Scope. The simulation model for calculating the proposed building performance and baseline building performance shall be developed in accordance with the requirements in Table G3.1 and other provisions of Section G3.
Change Summary:
The detailed HVAC system selection content from 2019's G3.1.1 has been moved to G3.2.1 and its subsections in 2022.
G3.1.3 - Additions 🟢 NEW
2022 Content:
Additions. The simulation model for calculating the proposed building performance and baseline building performance for additions shall be developed in accordance with the requirements in Section G3.2.
This is a new organizational structure in 2022 that reorganizes content previously in G3.1.x.
G3.2.1 - Baseline HVAC System Type and Description
2022 Content:
Baseline HVAC System Type and Description. HVAC systems in the baseline building design shall conform with the system descriptions in Table G3.1.1-4 and comply with the requirements in Sections G3.2.1 through G3.2.3.
G3.2.1.1 - Baseline HVAC System Types based on Building Area Types 🟢 NEW
2022 Content:
HVAC system types in the baseline building design shall be determined as follows:
(a) Determine the combined area of the gross conditioned floor area and semiheated floor area of each of the following building area types in the proposed design:
Residential. HVAC zones that include dwelling units, guest rooms, living quarters, private living spaces, and sleeping quarters, and residential associated HVAC zones shall be classified as residential. Other space types, including patient rooms in hospitals, shall not be classified as residential.
Public Assembly. Houses of worship, auditoriums, movie theaters, performance theaters, concert halls, arenas, enclosed stadiums, ice rinks, gymnasiums, convention centers, exhibition centers, and natatorium buildings shall be classified as public assembly.
Heated-Only Storage. Nonrefrigerated warehouse buildings and heated parking garages that are not mechanically cooled, shall be classified as heated-only storage.
Retail. Grocery stores, retail stores, and supermarket buildings with two floors or fewer shall be classified as retail.
Hospitals. Hospital building area types, including patient rooms, shall be classified as hospitals.
Other Nonresidential. Buildings and areas within buildings that are not classified as residential, public assembly, heated-only storage, hospital, or retail shall be classified as other nonresidential.
(b) Classify the nonresidential building area type with the largest combined area from Section G3.2.1.1(a) as the predominant nonresidential building area type. Add the combined area of any remaining nonresidential building area types with less than 1900 m² to the combined area of the predominant nonresidential building area type.
(c) Select a baseline HVAC system type from Table G3.1.1-3 for each of the following building area types included in the proposed design:
Residential based on Section G3.2.1.1(a)
Predominant nonresidential based on Section G3.2.1.1(b)
Each additional nonresidential building area type with more than 1900 m² of combined area based on Section G3.2.1.1(a)
G3.2.1.2 - Additional and Adjusted Baseline HVAC System Types 🟢 NEW
2022 Content:
Baseline HVAC systems shall be added or adjusted for individual HVAC zones based on the following criteria:
(a) If the baseline HVAC system type is 5, 6, 7, or 8 use separate single-zone systems conforming with the requirements of system 3 or system 4 for any HVAC zones that have occupancy, or internal gains that differ significantly from the rest of the HVAC zones served by the system. Total peak internal gains that also differ by 37.9 W/m² or more from the average of other HVAC zones served by the system, or occupied hours that are more than 40 hours per week higher than the average of other HVAC zones served by the system, are considered to differ significantly.
(b) In a building having a total laboratory exhaust rate greater than 7100 L/s, use a single system of type 5 or 7 serving only those HVAC zones that include the laboratory spaces. The lab exhaust fan shall be modeled as constant kilowatts reflecting constant-volume stack discharge with outdoor air bypass.
(c) HVAC zones designed with heating-only systems in the proposed design serving storage rooms, stairwells, vestibules, electrical/mechanical rooms, and restrooms not exhausting or transferring air from mechanically cooled thermal zones in the proposed design shall use system type 9 or 10 in the baseline building design.
(d) If the baseline HVAC system type is 9 or 10, use additional system types for all HVAC zones that are mechanically cooled in the proposed design.
KEY VALUE CHANGE:
Schedule difference metric
40 equivalent full-load hours per week
40 occupied hours per week
5, 6, 7, 8, 9, 10, 11, 12, or 13
G3.2.1.3 - Baseline System Grouping 🟢 NEW
2022 Content:
For baseline HVAC systems 1, 2, 3, 4, 9, 10, 11, 12, and 13, each HVAC zone or thermal block shall be modeled with its own HVAC system. For systems 5, 6, 7, and 8, each floor shall be modeled with a separate HVAC system. Floors with identical HVAC zones can be grouped for modeling purposes.
Exception to G3.2.1.3: Baseline system 5 or 7 serving laboratory spaces in accordance with Section G3.2.1.2(b) shall be modeled as a single system serving all laboratory HVAC zones regardless of floor.
G3.2.1.4 - Purchased Heat 🟢 NEW
2022 Content:
Purchased Heat. For systems using purchased hot water or steam, the heating source shall be modeled as purchased hot water or steam at the rates documented in accordance with Section G2.4.2.
G3.2.1.5 - Purchased Chilled Water
Content (Similar):
Purchased Chilled Water. For systems using purchased chilled water, the cooling source shall be modeled as purchased chilled water at the rates documented in accordance with Section G2.4.2.
G3.2.1.6 - Baseline HVAC System Requirements for Purchased Systems
G3.2.1.6.1 - Purchased Heat Only
G3.2.1.6.2 - Purchased Chilled Water Only
G3.2.1.6.3 - Purchased Chilled Water and Purchased Heat
G3.2.1.6.4 - On-Site Distribution Pumps
G3.2.1.7 - Modeling Building Envelope Air Leakage
🔵 RENUMBERED + 🟡 MODIFIED
Key Changes:
"Building Envelope Infiltration"
"Building Envelope Air Leakage"
ASTM E 779, ASTM E1827, or ASTM E3158
2022 Additional Standards:
Added ASTM E1827 and ASTM E3158 as acceptable testing methods for measuring air leakage rate
G3.2.2 - General Baseline HVAC System Requirements
G3.2.2.1 - Equipment Efficiencies
G3.2.2.2 - Equipment Capacities
G3.2.2.2.1 - Sizing Runs
G3.2.2.3 - Unmet Loads
G3.2.2.4 - Fan System Operation
G3.2.2.5 - Ventilation
G3.2.2.6 - Minimum Outdoor Air
G3.2.2.7 - Chilled-Water Pumps
G3.2.2.7.1 - Chilled-Water Loop Design
G3.2.2.7.2 - Condenser-Water Loop Design
G3.2.2.8 - Service Hot-Water Pumps
G3.2.2.8.1 - Hot-Water Loop
G3.2.2.9 - Dehumidification
G3.2.3 - Baseline Building Envelope
G3.2.3.1 through G3.2.3.19 - Envelope Subsections
All subsections have been renumbered from G3.1.3.x to G3.2.3.x:
2019 Section
2022 Section
Topic
Manual Fenestration Shading
Demand Controlled Ventilation
This is an entirely new major section in the 2022 edition addressing alterations that are not classified as "substantial alterations."
2022 Content:
The simulation model for calculating the proposed building performance shall be developed in accordance with the requirements in Table G3.1, Proposed Building Performance column and the following additional requirements:
New and retrofitted systems and equipment shall be consistent with design documents.
Systems and equipment excluded from the scope of retrofit shall reflect the existing conditions.
2022 Content:
(Parent section for baseline requirements specific to alterations)
G3.3.2.1 - General Approach 🟢 NEW
2022 Content:
System and equipment included in the scope of retrofit shall be modeled at efficiency levels meeting the mandatory and prescriptive requirements in Sections 5 through 10 and as described in this section. All other baseline systems and equipment shall be modeled the same as in the proposed design.
G3.3.2.2 - Schedules 🟢 NEW
2022 Content:
Schedules modeled in the baseline design are allowed to differ from the proposed design following Table G3.1(4), Baseline Building Performance column, Exceptions 1 through 3.
G3.3.2.3 - Building Envelope 🟢 NEW
2022 Content:
Building envelope that is not included in the scope of the alteration shall be modeled identically in the baseline building design and proposed design. Building envelope that is included in the scope of the alteration shall meet the requirements of Sections G3.2.3.1 through G3.2.3.19.
G3.3.2.4 - Lighting 🟢 NEW
2022 Content:
Lighting systems that are not included in the scope of the alteration shall be modeled identically in the baseline building design and proposed design. Lighting systems that are included in the scope of the alteration shall be modeled in accordance with Table G3.1(6).
G3.3.2.5 - HVAC Systems 🟢 NEW
2022 Content:
HVAC systems that are not included in the scope of the alteration shall be modeled identically in the baseline building design and proposed design...
G3.3.2.6 - HVAC System Fans 🟢 NEW
G3.3.2.7 - Service Water Heating 🟢 NEW
G3.3.2.8 - Receptacle and Process Loads 🟢 NEW
G3.3.2.9 - On-Site Renewable Energy 🟢 NEW
PART 2: TABLE COMPARISON
Table G3.1 - Modeling Requirements
Note: Title changed from "Modeling Requirements for Calculating Proposed and Baseline Building Performance" to "Modeling Requirements for Calculating Proposed Building Performance and Baseline Building Performance"
Table G3.1.1-1 through G3.1.1-4 - HVAC System Tables
Renumbered Tables (G3.1.2.x → G3.2.2.x)
2019 Table
2022 Table
Content
Part-Load Performance Curves
Service Hot-Water Pump Power
Renumbered Tables (G3.1.3.x → G3.2.3.x)
2019 Table
2022 Table
Content
Building Envelope Tables (G3.4 Series)
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
⚪ Review for value changes
Equipment Efficiency Tables (G3.5 Series)
Lighting Tables (G3.6, G3.7, G3.8)
Note: The single Table G3.7 (Space-by-Space Method) in 2019 has been split into two tables in 2022.
Motor and Elevator Tables (G3.9 Series)
⚪ Building Performance Factor
PART 3: SUMMARY OF KEY CHANGES
Structural Changes Summary
Change Type
Count
Description
Including G3.3.x series for alterations
G3.1.2.x→G3.2.2.x, G3.1.3.x→G3.2.3.x
Table G3.7 → G3.7-1 and G3.7-2
Table G3.4-9, Table G3.7-2
Content Changes Summary
Parameter
2019 Value
2022 Value
Schedule difference metric
40 equivalent full-load hours/week
ASTM E779, E1827, or E3158
NEW requirement (see below)
🟢 NEW: Thermal Bridging Requirements (Table G3.1 - Building Envelope)
This is a significant NEW addition in 2022 that did not exist in 2019.
Each linear thermal bridge and point thermal bridge as identified in Section 5.5.5 shall be modeled using either of the following techniques:
A separate model of the assembly within the energy simulation model.
Adjustment of the clear-field U-factor in accordance with Section A10.2.
Each uninsulated assembly not identified in Section 5.5.5 shall be modeled using either of the following techniques:
A separate model of the assembly within the energy simulation model.
The U-factors of uninsulated assemblies can be averaged with larger adjacent surfaces of the same class of construction using an area-weighted average method.
Linear and Point Thermal Bridges. Where linear thermal bridges and point thermal bridges, as identified in Section 5.5.5 are modeled in the proposed design, they shall not be modeled in the budget building design.
Thermal bridge modeling in proposed design
Required per Section 5.5.5
Thermal bridge modeling methods
Two options: direct modeling OR U-factor adjustment per A10.2
Thermal bridges in baseline
Explicitly excluded from baseline when modeled in proposed
Reference to Section 5.5.5
Multiple references for thermal bridge identification
Reference to Section A10.2
New reference for U-factor adjustment methodology
This change means that projects using the Performance Rating Method in 2022 must now:
Identify linear and point thermal bridges per Section 5.5.5
Model these thermal bridges in the proposed design using approved methods
NOT include thermal bridges in the baseline building design (creating a credit opportunity for addressing thermal bridges)
PART 4: KEY ADDENDA AND TECHNICAL CHANGES
This section summarizes the major addenda that drove changes between 2019 and 2022, based on the ASHRAE Journal article "ASHRAE/IES Standard 90.1-2022 Performance Path Changes" (November 2023).
The BPF values in Table 4.2.1.1 were recalculated using a fundamentally different approach.
Aspect
2019 Methodology
2022 Methodology
Ratio of regulated loads in prototype models compliant with current 90.1 vs. 90.1-2004
New prototype models configured to align with Appendix G baseline rules
Based on 2004 prototype configurations
Aligned with Appendix G baseline system types and assignments
~60% of BPFs became less stringent
More accurate representation of actual baseline performance
Why this matters: The old methodology didn't account for differences between 2004 prototype model configurations and actual Appendix G baseline modeling requirements. PNNL developed new prototypes that better match what modelers actually create when following Appendix G rules.
A persistent pain point for energy modelers has been finding appropriate performance curves for baseline/budget chillers. This addendum adds Appendix J: Sets of Performance Curves.
Not prescribed; modelers used software defaults
Prescribed curves in Appendix J
Budget chiller curves (ECBM)
Prescribed curves in Appendix J
Proposed design (no manufacturer data)
Software defaults or custom curves
Default curves provided in Appendix J
Practical impact:
Eliminates inconsistency between simulation programs using different default curves
Removes the need for modelers to create custom curves (which requires expertise most don't have)
Ensures baseline/budget chillers reflect intended IPLV values
Particularly helpful when proposed design doesn't include a chiller but baseline requires one
Addendum af: Lighting Clarifications
Three specific lighting modeling issues were addressed:
Change 1: Lighting Power Method Consistency
Lighting neither exists nor designed
Same method for proposed and baseline
Use Space-by-Space Method
Baseline when proposed uses BAM
Change 2: Exterior Lighting (Non-Tradable Surfaces)
Baseline had separate allowances
Baseline = same as proposed for non-tradable surfaces
Change 3: Retail Display Lighting
Not specifically addressed
Baseline = lesser of Section 9.5.2.2(b) limits or proposed
Addendum ch: Alternative Metrics (NEW Appendix I)
New Informative Appendix I provides alternative compliance metrics for jurisdictions that don't want to use energy cost.
Metric
Table Reference
Purpose
Direct energy consumption
Accounts for generation/transmission losses
Supports decarbonization goals
Why this exists: Using cost metrics with the PRM's independent baseline can discourage electrification in areas where electricity costs are high relative to gas. Site energy, source energy, or carbon metrics can better align with policy goals.
The appendix also includes:
Methodology for calculating custom BPFs using local energy costs or conversion factors
Sample amendment language showing how jurisdictions would adopt alternate metrics
Addenda ck & cp: Renewable Energy Requirements
New Prescriptive Requirement (Section 10.5.1.1)
2022 requires on-site renewable energy:
Not less than 0.50 W/ft² (5.4 W/m²) multiplied by the sum of the gross conditioned floor area for all floors up to the three largest floors
5% limit on renewable trade-offs
5% limit in excess of required amount
PCIt equation modified with PRE term; baseline has no renewables
Where PRE caps renewable credit at 5% above prescriptive requirement.
Translation: You can't just slap a huge PV array on a mediocre building and call it compliant. The building itself still needs to perform.
Addendum u: ECBM Economizer and HVAC System Changes
Economizer Type Simplification
Budget economizer type = same as proposed
Budget always uses air economizers
Why: Fluid economizers are complicated to model. Air economizers are straightforward. This also clarifies what to do when the proposed design has no economizer at all.
Equipment Capacity Methodology (New Section 12.5.2.i)
Added clear rules for determining budget equipment capacities when thermal blocks are combined:
Budget System Type
Capacity Basis
Thermal block load ÷ number of combined HVAC zones
Total load of all thermal blocks ÷ total number of HVAC systems
Addendum ab: PRM Baseline System Selection Clarifications
The baseline HVAC system selection process was clarified with a step-by-step methodology:
Step 1: Residential Spaces
All residential spaces, regardless of building size, use System Type 1 or 2 (based on climate zone).
Step 2: Nonresidential Spaces on Residential Floors
Corridors, storage, restrooms, lounges, offices that primarily serve residents and are on floors where majority is residential → System Types 3 or 4
Step 3: Baseline System Selection Process
Calculate combined floor area of conditioned + semi-heated floors by building area type
Identify predominant nonresidential building area type (largest floor area)
Any building area type < 20,000 ft² (1,858 m²) → treated as part of predominant type
Assign baseline systems for residential, predominant, and any other types > 20,000 ft²
Apply zone-specific modifications based on criteria in new section
Addendum co: PRM Retrofits (NEW Section G3.3)
Prior to 2022, PRM didn't distinguish between new construction and retrofits, which created situations where PRM was more stringent for retrofits than other compliance paths. The fix:
Substantial Alterations (per Section G3.1.4(a))
Table 4.2.1.1 value × 1.05
Standard Appendix G methodology
Limited Alterations (NEW Section G3.3)
New/retrofitted systems per design docs; existing systems per existing conditions
Same as proposed, except retrofit scope items modeled at minimum prescriptive compliance
Mixed Projects (Existing Building + Addition)
BPF = area-weighted average of:
Existing building BPF (per Section 4.2.1.3)
Addition BPF (from Table 4.2.1.1)
Addendum cr: Envelope Backstop (NEW G1.2.1)
This addresses the concern that weak envelopes can permanently limit building performance because envelope retrofits are expensive and unlikely.
For new buildings, one of the following must be met:
Option 1: Envelope complies prescriptively with Section 5.5
Option 2: Using Section 5.6 (Envelope Trade-Off), the proposed envelope performance factor shall not exceed the base envelope performance factor by more than:
Building Type
Maximum Exceedance
Multifamily, Hotel/Motel, Dormitory
Calculation method: Uses COMcheck software per Appendix C methodology.
Why this matters: You can no longer trade away envelope performance for efficient HVAC and lighting. The envelope has to be at least reasonably close to prescriptive requirements.
Addendum av: Thermal Bridging
Specifies how thermal bridges are modeled in baseline and proposed designs. (See Thermal Bridging section in Part 3 for details.)
Addendum t: Envelope Air Leakage
Specifies requirements for simulating envelope air leakage in both baseline and proposed buildings, including the change from single test method to multiple options:
ASTM E779, E1827, or E3158
Other Notable Addenda (Quick Reference)
Clarifies base space conditioning categories
Clarifies area-weighted BPF procedure for mixed-use buildings
Clarifies baseline fenestration apportionment
Fixes SI inconsistencies for fan power
Linear interpolation for transformer efficiency between size ranges
Consolidates fan system operation requirements
Baseline CW/HW pumps run only when load exists
"Water-cooled" → "fluid-cooled" terminology
Aligns PRM documentation requirements with ECBM
Exception from baseline energy recovery for labs with exhaust > 15,000 cfm
Baseline chillers sized on peak coincident load
Clarifies WWR determination; baseline excludes automatic shading
Updates PV temperature coefficient for PVWatts consistency
Baseline high-capacity gas boilers and SWH must meet prescriptive requirements
No baseline fan power credit for energy recovery when not in baseline
Solar reflectance requirements for baseline walls
Both ECBM and PRM
Updates Standard 140 required testing for simulation programs
Expands applicability to building sites and properties
Informative note recommending ASHRAE Standard 209
Clarifies documentation (including simulation files) to AHJ
Renumbers reference sections for consistency
PART 5: COMPLETE EXCEPTIONS COMPARISON
This section lists ALL exceptions from both the 2019 and 2022 editions of Appendix G, organized by section number.
2019:
Energy used to recharge or refuel vehicles that are used for off-building site transportation purposes shall not be modeled in the baseline building performance or the proposed building performance.
2022:
Energy used to recharge or refuel vehicles that are used for off-site transportation purposes shall not be modeled in the baseline building performance or the proposed building performance.
Change: Minor wording change from "off-building site" to "off-site"
Table G3.1 Exceptions - Design Model (Proposed Building)
Exception - Heating Only Systems
Spaces designed with heating only systems serving storage rooms, stairwells, vestibules, electrical/mechanical rooms, and restrooms not exhausting or transferring air from mechanically cooled thermal zones in the proposed design shall not be modeled with mechanical cooling.
Exception - Space Use Classification
Where space types neither exist nor are designated in design documents, use type shall be specified in accordance with Section 9.5.1
Table G3.1 Exceptions - Schedules (Baseline Building)
Exceptions 1-3 for Schedules
Exception 1: Set points and schedules for HVAC systems that automatically provide occupant thermal comfort via means other than directly controlling the air dry-bulb and wet-bulb temperature may be allowed to differ, provided that equivalent levels of occupant thermal comfort are demonstrated via the methodology in ASHRAE Standard 55, Section 5.3.3, "Elevated Air Speed," or Standard 55, Appendix B.
Exception 2: Schedules may be allowed to differ between proposed design and baseline building design when necessary to model non-standard efficiency measures, provided that the revised schedules have been approved by the rating authority.
Exception 3: HVAC system fan schedules may be allowed to differ when Section G3.2.1.2(a) applies. (Note: 2019 referenced G3.1.1(b); 2022 references G3.2.1.2(a))
Table G3.1 Exceptions - Building Envelope
Exceptions - Building Elements Permitted to Differ from Drawings
2019 Exceptions allowed:
Exterior surfaces whose azimuth orientation and tilt differ by less than 45 degrees
Roof surface modeling with aged solar reflectance
2022 Exceptions (EXPANDED):
NEW: Each linear thermal bridge and point thermal bridge as identified in Section 5.5.5 shall be modeled using either:
A separate model of the assembly within the energy simulation model
Adjustment of the clear-field U-factor in accordance with Section A10.2
NEW: Each uninsulated assembly not identified in Section 5.5.5 shall be modeled using specified techniques
NEW: Any other building envelope assembly not subject to Section 5.5.5 that covers less than 5% of total area
Exterior surfaces whose azimuth orientation and tilt differ by less than 45 degrees
Roof surface modeling with aged solar reflectance
Exception - Air Leakage Testing
When whole-building air leakage testing, in accordance with Section 5.4.3.1.1, is specified during design and completed after construction, the proposed design air leakage rate of the building envelope shall be as measured.
Exceptions - Baseline Building Orientation
Exception 1: If it can be demonstrated to the satisfaction of the rating authority that the building orientation is dictated by site considerations.
Exception 2: Buildings where the vertical fenestration area on each orientation varies by less than 5%.
Exception - Semiheated Space Conditioning 🟢 NEW in 2022
2022:
Envelope components of the HVAC zones that are semiheated in the proposed design must meet conditioned envelope requirements in Tables G3.4-1 through G3.4-8 if, based on the sizing runs, these zones are served by a baseline system with sensible cooling output capacity ≥15 W/m² of floor area, or with heating output capacity greater than or equal to the criteria in Table G3.4-9, or that are indirectly conditioned spaces.
Table G3.1 Exceptions - Lighting
Exception - Lighting Power Reduction
Lighting use can be reduced for the portion of the space illuminated by the specified fixtures provided that they maintain the same illuminance level as in the baseline. Such reduction shall be demonstrated by calculations.
Table G3.1 Exceptions - Thermal Blocks
Exceptions - Combining HVAC Zones
Different HVAC zones may be combined to create a single thermal block or identical thermal blocks to which multipliers are applied, provided that all of the following conditions are met:
All HVAC zones in the thermal block that are adjacent to glazed exterior walls face the same orientation or their orientations vary by less than 45 degrees
All HVAC zones in the thermal block have the same thermostat setpoints or maximum 1.1°C difference
All HVAC zones are served by the same system or by systems of the same type
Table G3.1 Exceptions - HVAC Systems
Exception - Baseline HVAC System Types 9 and 10
Spaces using baseline HVAC system types 9 and 10. (Exception to cooling system requirements)
Exception - Humidification System
If the proposed building humidification system complies with Section 6.5.2.4 then the baseline building design shall use nonadiabatic humidification.
Exception - Natural Gas Not Available
For fossil fuel systems where natural gas is not available for the proposed building site as determined by the rating authority, the baseline HVAC systems shall be modeled using propane as their fuel.
2022:
Exception to (a) and (b): Where part-load performance of chillers in the proposed design is not available, and design temperature across the condenser is 5.56°C, the performance curves in Normative Appendix L, as referenced in Table J-1, shall be modeled for the specified chiller. When using performance curves from Normative Appendix L, chiller minimum part-load ratio and minimum compressor unloading ratio shall be equal to 0.25.
Exception - Condenser Heat Recovery
If a condenser heat recovery system meeting the requirements described in Section 6.5.6.2 cannot be modeled, the requirement for including such a system in the actual building shall be met as a prescriptive requirement in accordance with Section 6.5.6.2, and no heat recovery system shall be included in the proposed design or baseline building design.
Table G3.1 Exceptions - Service Water Heating
Exceptions - SWH System Types
Multiple exceptions for service water heating system configurations based on fuel availability and system types.
Exception - Natural Gas Not Available for SWH
Where natural gas is not available for the proposed building site, as determined by the rating authority, gas storage water heaters shall be modeled using propane as their fuel.
Table G3.1 Exceptions - Receptacle and Process Loads
Exception - Receptacle Controls
When receptacle controls installed in spaces where not required by Section 8.4.2 are included in the proposed building design, the hourly receptacle shall be reduced as follows: 10% for the first level of control and 15% additional for the second.
Exception - Process Loads Variations
When quantifying performance that exceeds the requirements of Standard 90.1 (but not when using the Performance Rating Method as an alternative path for minimum standard compliance per Section 4.2.1.1) variations of the power requirements, schedules, or control sequences of the equipment modeled in the baseline building design from those in the proposed design shall be approved by the rating authority...
Exception to G3.1.1.4 / G3.2.1.7 - Building Envelope Air Leakage
A multizone airflow model alternative method to modeling building envelope air leakage may be used, provided the following criteria are met:
Where the calculations are made independently of the energy simulation program, the proposed method must comply with Section G2.5.
The method for converting the air leakage rate of the building envelope at 75 Pa, to the appropriate units for the simulation program is fully documented and submitted to the rating authority for approval.
Exception to G3.1.2.2.1 / G3.2.2.2.1 - Sizing Runs
For cooling sizing runs in residential dwelling units, the infiltration, occupants, lighting, gas and electricity using equipment hourly schedule shall be the same as the most used hourly weekday schedule from the annual simulation.
Exception to G3.1.2.4 / G3.2.2.4 - Fan System Operation
For Systems 6 and 8, only the terminal-unit fan and reheat coil shall be energized to meet heating set point during unoccupied hours.
2022 adds additional exception:
For baseline systems serving only laboratory spaces that are prohibited from recirculating return air by code or accreditation standards, the baseline system shall be modeled as 100% outdoor air.
Exception to G3.1.2.5 / G3.2.2.4 - Ventilation
Exception (a): When modeling demand control ventilation in the proposed design in systems with outdoor air capacity ≤1400 L/s serving areas with an average design capacity of 100 people per 93 m² or less.
Exception (b): When designing systems in accordance with Standard 62.1, Section 6.2, "Ventilation Rate Procedure," reduced ventilation airflow rates may be calculated for each HVAC zone in the proposed design with a zone air distribution effectiveness (Ez) > 1.0.
Exception to G3.1.2.6 / G3.2.2.5 - Economizers
Economizers shall not be included for systems meeting one or more of the following:
Gas-phase air cleaning (Std 62.1, Section 6.1.2)
Supermarket open refrigerated casework
Computer rooms (Section G3.1.2.6.1 / G3.2.2.5.1)
Exceptions to G3.1.2.8.1 / G3.2.2.7.1 - Supply Air Temperature (Systems 1-8, 11-13)
Exception (a): For systems serving laboratory spaces, airflow rate shall be based on a supply-air-to-room temperature set-point difference of 9°C or the required ventilation air or makeup air, whichever is greater.
Exception (b): If the proposed design HVAC system airflow rate based on latent loads is greater than the design airflow rate based on sensible loads, then the same supply-air-to-room-air humidity ratio difference (gr/kg) used to calculate the proposed design airflow shall be used to calculate design airflow rates for the baseline building design.
Exception to G3.1.2.10 / G3.2.2.9 - Exhaust Air Energy Recovery
If any of these exceptions apply, exhaust air energy recovery shall not be included in the baseline building design:
Spaces not cooled, heated <16°C
Toxic, flammable, corrosive fumes
Commercial kitchen hoods (Type 1)
Cooling systems CZ 3C, 4C, 5B, 5C, 6B, 7, 8
Largest exhaust <75% of outdoor airflow
Systems with dehumidification using series energy recovery
Exception to G3.1.3.4 / G3.2.3.4 - Hot-Water Supply Temperature Reset
Systems served by purchased heat.
Exception to G3.1.3.5 / G3.2.3.5 - Hot-Water Pumps
The pump power for systems using purchased heat shall be 220 W·s/L.
Exception to G3.1.3.7 / G3.2.3.7 - Type and Number of Chillers
Systems using purchased chilled water shall be modeled in accordance with Section G3.1.1.3 / G3.2.1.6.
Exception to G3.1.3.9 / G3.2.3.9 - Chilled-Water Supply Temperature Reset
Exception (a): If the baseline chilled-water system serves a computer room HVAC system, the supply chilled-water temperature shall be reset higher based on the HVAC system requiring the most cooling. The maximum reset chilled-water supply temperature shall be 12°C.
Exception (b): Systems served by purchased chilled water.
Exception to G3.1.3.10 / G3.2.3.10 - Chilled-Water Pumps
For systems using purchased chilled water, the building distribution pump shall be modeled with variable-speed drive, a minimum flow of 25% of the design flow rate, and a pump power of 250 kW/1000 L/s.
Exception to G3.1.3.13 / G3.2.3.13 - VAV Minimum Flow Set Points
Systems serving laboratory spaces shall reduce the exhaust and makeup air volume during unoccupied periods to the largest of 50% of zone peak airflow, the minimum outdoor airflow rate, or the airflow rate required to comply with applicable codes or accreditation standards.
Exception to G3.2.1.3 - Baseline System Grouping 🟢 NEW in 2022
Baseline system 5 or 7 serving laboratory spaces in accordance with Section G3.2.1.2(b) shall be modeled as a single system serving all laboratory HVAC zones regardless of floor.
G3.3 Exceptions - Alterations (Other Than Substantial) 🟢 ALL NEW in 2022
Exception to G3.3.2.8(a) - HVAC System Types
If the proposed design includes variable refrigerant flow heat pumps or single-zone systems with electric resistance heat, then air source heat pumps shall be used in the baseline design.
Exception to G3.3.2.8(d) - Fan Power for Energy Recovery
When a proposed design includes energy recovery but it is not required in the baseline building design per Section 6.5.6, the fan power of the baseline system shall be equal to either the proposed design system or the fan power limit in Section 6.5.3.1 calculated without fan power credit for energy recovery, whichever is less.
Summary of Exceptions Changes
Category
2019 Count
2022 Count
Change
Formal "Exception to G#.#.#" sections
Table G3.1 inline exceptions
G3.3 Alterations exceptions
New Exceptions in 2022:
Exception to G3.2.1.3 - Laboratory baseline system grouping
Exception to G3.3.2.8(a) - VRF/electric resistance → heat pump baseline
Exception to G3.3.2.8(d) - Fan power for energy recovery in alterations
Chiller part-load performance exception (Table G3.1)
Semiheated space conditioning exception (Table G3.1)
Largest exhaust <75% of outdoor airflow (exhaust air energy recovery)
100% outdoor air for laboratory spaces (fan system operation)
Thermal bridging modeling exceptions (Table G3.1, Building Envelope)
