Overhaul of ASHRAE 90.1 Brings New Requirements

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

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.

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