ASHRAE heating/cooling standards balance efficiency and comfort

Editor's note: The Energy Services Bulletin features real answers to questions posed to our staff at the Energy Services Power Line. We hope you find it useful.

Question: For heating and cooling commercial buildings, what thermostat settings maximize efficiency while still maintaining occupants' comfort?

Answer: The 17-page long ASHRAE Standard 55-1992, Thermal Environmental Conditions for Human Occupancy contains a self-explanatory chart that answers your question about acceptable comfort ranges. According to ASHRAE studies, most people are comfortable when the temperature is kept within the hashed area of the chart.

To minimize energy use, aim for the low end of the winter range and the high end of the summer range. In a dry climate, using humidifiers during the winter would allow you to keep the thermostat a little lower. Without humidification, around 70° F in the winter and 79° F in the summer will be near enough to the acceptable extremes to be energy-efficient without causing complaints.

A table version of the chart gives temperature recommendations based on relative humidity.

For more information on this standard, visit the ASHRAE Web site. If you have further questions on these building standards or other energy-related topics, please contact the Power Line at 1-800-769-3756.