News Brief

Updated Thermal Comfort Standard Could Save Energy

The 2013 version of ASHRAE’s Standard 55 allows designers to reduce energy use by incorporating adaptive thermal comfort strategies.

A new provision recognizing air movement as a cooling strategy in naturally ventilated buildings may make compliance to ASHRAE’s Thermal Comfort Standard more achievable without air conditioning systems.

Photo: Official U.S. Navy Imagery. License: CC BY 2.0.
ASHRAE has published its latest update to Standard 55, Thermal Environmental Conditions for Human Occupancy, with some major revisions that make room for adaptive thermal comfort principles.

Especially notable are two new revisions that may provide for energy savings by giving designers more flexibility, according to Gwelen Paliaga, chair of the committee that wrote the standard. Older versions of the standard allowed a wider range of temperatures in naturally ventilated buildings, but the new version extends the comfort threshold even further if air movement is also utilized. This may make compliance to the standard more achievable for naturally ventilated buildings. In addition, the calculation tools are well established, according to Paliaga, because the standard already accounts for the cooling effect of air movement in mechanically conditioned spaces.

There is also an alternate procedure for estimating the amount of insulation occupants get from their clothing, which is based on updated field research that takes weather into account. A predictive model that estimates how much warm clothing occupants will wear throughout the seasons can be used to more accurately calculate the optimal thermostat setpoints for design calculations and annual simulations.

The standard incorporates 18 new addenda overall and has been reorganized so that calculation procedures appear sequentially. “The standard had been very theoretical, and now it’s much more of a design procedure,” Paliaga told EBN. “LEED users will find the difference to be night and day.” Standard 55-2013 can be purchased through ASHRAE’s online bookstore.

Published February 3, 2014

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