The energy standard for buildings has been revised: ANSI/ASHRAE/IES 90.1-2019: Energy Standard For Buildings Except Low-Rise Residential Buildings.
The earliest human shelters guarded Paleolithic gatherers with basic protection from the elements and few amenities. Today, things are quite different, as buildings comprise complex systems that provide occupants with comfortable, safe, and attractive living and working environments. However, this necessitates superior architecture and engineering designs and quality construction practices. In result, lighting, major appliances, electronics, and heating, ventilation, and air conditioning (HVAC) can consume a great deal of energy.
As noted by the U.S. Department of Energy (DOE), the buildings sector accounts for about 76% of electricity use and 40% of all U.S. primary energy use and associated greenhouse gas (GHG) emissions. To face energy and environmental challenges, it is crucial to reduce energy consumptions in buildings. This also can lower costs to building owners and tenants.
ANSI/ASHRAE/IES 90.1-2019 helps meet this need by offering minimum energy-efficient guidelines for the design, construction, operation, and maintenance of buildings. It applies to new buildings and new portions of buildings and their systems, new systems and equipment in existing buildings, and new equipment or building systems specifically identified in the standard that are part of industrial or manufacturing processes. The standard also provides criteria for determining compliance with these specifications.
ANSI/ASHRAE/IES 90.1-2019 does not apply to single-family houses, multifamily structures of three stories or fewer above grade, manufactured houses (mobile homes), manufactured houses (modular), and buildings that use neither electricity nor fossil fuel.
Changes to ANSI/ASHRAE/IES 90.1-2019
ANSI/ASHRAE/IES 90.1-2019 revises the 2016 edition of the same American National Standard. In all, the current edition incorporates over 100 addenda to the 2016 edition, as well as numerous energy-saving measures. Changes were made to various areas throughout, including administration and enforcement, the building envelope, lighting, mechanical, energy cost budget (ECB), the performance rating method, and compliance paths.
Notable changes to ANSI/ASHRAE/IES 90.1-2019 include:
- “Commissioning requirements” were added to the standard.
- Substantial expansions to section 4.2.5, “Verification, Testing, and Commissioning.”
- New Informative Appendix H, “Additional Guidance for Verification, Testing, and Commissioning.”
- The categories of “nonmetal framed” and “metal framed” products were combined for vertical fenestration.
- Minimum criteria for solar heat gain coefficient (SHGC) and U-factor were upgraded across all climate zones.
- The air leakage section was revised to clarify compliance.
- In the vestibule section, the standard refined exceptions and added a new option for using air curtains.
- To reflect the outcomes of the fully reconstructed ANSI/ASHRAE Standard 90.1 lighting model, lighting power allowances for the Space-by-Space Method and the Building Area Method were modified. As mentioned in the standard, this model is “more representative of real-world conditions with the inclusion of updated IES recommendations, room cavity ratios, additional surface reflectance categories, light loss factors, and a 100% LED technology baseline with updated efficacy values.”
- New section 9.2, “Compliance Paths,” was added to cover a simple approach for designers who design or renovate office and retail buildings up to 25,000 ft2.
- Lighting control information for parking garages were updated to account for the use of LED. The new edition increases “the stringency of the setback requirement to 50%” and reduces “the control timeout from 20 minutes to 10 minutes.”
- Daylight responsive information was updated from continuous dimming or stepped control to continuous dimming for all spaces.
- New definition added for continuous dimming based on NEMA LSD-64-2014.
- Side-lighting guidance was updated to clarify that the setback distance is a horizontal measurement, and the exception was amended to include natural objects as an obstruction.
- Designers now have to option to use ANSI/ASHRAE 90.4 instead of ANSI/ASHRAE 90.1 in computer rooms that have an IT equipment load larger than 10 kW.
- Pump definitions, requirements, and efficiency tables are included in the standard.
- Table F-4, “Residential Furnaces—Minimum Efficiency Requirements for U.S. Applications (see 10 CFR 430),” and Table F-5, “Residential Boiler Minimum Efficiency Requirements for U.S. Applications (see 10 CFR 430),” were created for U.S. federally covered furnace products and to specify USDOE-covered residential water boiler efficiency requirements.
- The efficiency table for liquid-to-liquid heat exchangers was removed.
- Table 6.8.9-17, “Ceiling-Mounted Computer-Room Air Conditioners—Minimum Efficiency Requirements,” was added.
- Table 6.8.1-16, “Heat-Pump and Heat Recovery Chiller Packages—Minimum Efficiency Requirements,” was added, along with new guidance for heat pump and heat reclaim chillers.
- New information for vacuum insulating glazing was added to the list of options for section 6.4.5, “Walk-In Coolers and Walk-In Freezers.”
- The fan efficiency grade (FEG) efficiency metric was replaced with fan energy index (FEI).
- Section 22.214.171.124.2, “Fan Motor Selection,” was updated to increase design options for load-matching variable-speed fan applications.
- Section 126.96.36.199, “Ceiling Fans,” includes new information for reporting fan power.
- Energy recovery information was included for high-rise residential buildings.
- New information was added for condenser heat recovery for acute care inpatient hospitals.
- The baseline was set for on-site electricity generation systems in section 11, “Energy Cost Budget Method.”
- Rules in Normative Appendix G, “Performance Rating Method,” were clarified when combining multiple thermal zones into a single thermal block.
- Explicit heating and cooling coefficients of performance (COPs) were provided without fan for baseline packaged cooling equipment.
- Rules were added for modeling the impact of automatic receptacle controls.
- More specific baseline rules were set for infiltration modeling.
- Clarification was added on performing plant and coil sizing.
- Building performance factors were updated.
- Clearer rules were added to how renewables are treated.
- Numerous updates were added to the rules for lighting modeling.
ANSI/ASHRAE/IES 90.1-2019: Energy Standard For Buildings Except Low-Rise Residential Buildings is available on the ANSI Webstore.
Energy Standard for Low-Rise Residential Buildings
Users should note that there is an exception to this standard noted explicitly in its title: low-rise residential buildings. The purpose of ANSI/ASHRAE/IES 90.1-2019 is:
“To establish the minimum energy efficiency requirements of buildings other than low-rise residential buildings.”
Low-rise residential buildings are defined here as:
“single-family houses, multifamily structures of three stories or fewer above grade, manufactured houses (mobile homes), and manufactured houses (modular).”
Energy efficiency guidelines for these buildings are specified in a separate document, ANSI/ASHRAE/IES 90.2-2018: Energy-Efficient Design Of Low-Rise Residential Buildings, which is also available on the ANSI Webstore.
If you’d like to learn more about this standard, please refer to our post ANSI/ASHRAE 90.2-2018: Energy-Efficient Design Of Low-Rise Residential Buildings.