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ASHRAE Releases New Energy Standard

ASHRAE Releases New Energy Standard

In October 2019, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published ANSI/ASHRAE/IES Standard 90.1-2019, Energy Efficiency Standard for Buildings Except Low-Rise Residential Buildings. With more than 100 changes from the 2016 version, the standard contains significant changes related to administration, enforcement, commissioning, mechanical, and lighting.

For lighting, the 2019 version generally reduces interior power allowances, tweaks several control requirements, ties control functional testing into building commissioning, and introduces a new, simplified compliance method for office, school, and retail buildings.

Commercial building energy codes regulate the design energy efficiency of nonresidential buildings. While some states such as California write their own codes, many adopt (or adapt) model codes such as ASHRAE/ANSI/IES 90.1 and the International Energy Conservation Code (IECC). While the IECC is predominant, 90.1 remains influential as the national reference code recognized by the Department of Energy. The 90.1 standard is typically referenced in building rating systems, and IECC recognizes it as an alternative compliance standard.

Lighting power. The first big change in the 2019 version is a general reduction in interior lighting power allowances, which recognizes the growing efficacy and cost-effectiveness of LED technology. Looking at whole building lighting power allowances, several building types saw increases, but generally they were reduced, in some cases significantly. Staple building types office, retail, school/university, hospital, and manufacturing, for example, saw roughly 10-20 percent reductions.

Exterior lighting, meanwhile, saw a few reductions for various applications, though the majority remained unchanged. The 2019 version of 90.1 adds a provision for calculating the power allowance for applications not listed or not comparable with any listed.

New compliance method. Lighting designers seeking to comply with 90.1 typically have a choice of the Building Area Method, Space by Space Method, or complex building modeling. The 2019 version introduces a new, simplified path for buildings in which at least 80 percent of the floorspace is used as an office, school, or retail building. Each building type has its own table, which lists applications and the lighting power and control requirements for each. Another table lists exemptions, one of which is for luminaire and lamp/ballast replacements; for this type of project, the designer must achieve a minimum power reduction based on the incumbent technology being replaced.

Lighting controls. For controls, several requirements are updated. The 2019 version of 90.1 requires the power for each parking garage luminaire to be reduced by at least 50 percent when no activity is detected for 10 minutes. In daylight areas, the photocontrol must reduce lighting power by at least 80 percent (including OFF) via continuous dimming and in response to daylight. If another partial-OFF control reduces power, the photocontrol can adjust it based on daylight but may not increase power above the partial-OFF level. Photocontrol calibration is now the same for toplighting as for sidelighting. Additionally, 90.1-2019 added a definition of “continuous dimming” based on NEMA LSD-64-2014.

Overall, ASHRAE/ANSI/IES 90.1-2019 continues the trend toward lower interior lighting power allowances because of the LED revolution, while tweaking control requirements and offering a new, simplified compliance path. While it may be some time before the 2019 version of the standard sees adoption, it may be useful for distributors to begin familiarizing themselves with its requirements.

For more information, consult ASHRAE/ANSI/IES 90.1-2019, available at the ASHRAE bookstore at

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Craig DiLouie

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