News Brief

Overhaul of ASHRAE 90.1 Brings New Requirements

The 2013 energy standard will require more stringent equipment efficiencies and lighting thresholds.

Interior lighting power densities are again lowered for the latest version of ASHRAE 90.1, but there is also a strong focus on daylighting requirements to achieve energy-efficiency goals.

Photo: Joel Bradshaw
The recently published 2013 version of ANSI/ASHRAE/IES 90.1 includes significant revisions to building envelope, lighting, and mechanical appliance requirements, making the standard 40%–50% more stringent than the 2004 version, according to ASHRAE.

Containing more than 100 changes from the previous 2010 version, the standard’s fenestration requirements now include double glazing in many climates and establish a minimum visible transmittance/solar heat gain coefficient (VT/SHGC) ratio to allow daylighting with minimum solar gain. Minimum efficiencies are increased for chillers, heat pumps, and air conditioners, as well as being established for fans for the first time.

In lighting, “the focus in the 2013 standard was not just on lowering interior lighting power densities but on finding ways to achieve savings by adding more controls and daylighting requirements” according to Rita Harrold, director of technology for the Illuminating Engineering Society of North America. The standard thus includes more stringent space-by-space lighting power density limits and thresholds for top lighting.

Standard 90.1 acts as a benchmark for commercial building energy codes and can apply to all but low-rise residential buildings. It will likely take a few years to become widely used: ASHRAE 90.1-2010 is referenced in LEED version 4, which comes out in November 2013, and 90.1-2007 and 90.1-2004 are still commonly used in local building codes.

For more information:

ASHRAE’s Online Bookstore

Published November 1, 2013

Pearson, C. (2013, November 1). Overhaul of ASHRAE 90.1 Brings New Requirements. Retrieved from

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