ASHRAE hits back at “sexist” ac study

USA: ASHRAE has hit back at the Maastricht University study suggesting that methods to determine thermal comfort are biased against women.

The study by Boris Kingma and Wouter van Marken Lichtenbelt of Maastricht University has received wide media attention over the last few days. Most reports have accused air conditioning of being sexist in being designed to provide the ideal temperature for the “hot-bloodied” male – a temperature too low for women.

The research was critical of the ANSI/ASHRAE Standard 55, the generally-accepted thermal comfort standard. The standard specifies the combinations of indoor thermal environmental factors and personal factors that will produce thermal environmental conditions acceptable to a majority of the occupants within the space.

Bjarne Olesen PhD, a member of the ASHRAE board of directors, internationally-renowned thermal comfort research and former chair of the Standard 55 committee maintains that the interpretation of the authors regarding the basis for Standard 55 is not correct.

“The part of the standard they are referring to is the use of the PMV/PPD index. This method is taken from an ISO/EN standard 7730, which has existed since 1982. The basic research for establishing comfort criteria for the indoor environment was made with more than 1,000 subjects with equal amount of women and men.

“In the main studies, where they did the same sedentary work and wore the same type of clothing, there were no differences between the preferred temperature for men and women. So the researchers’ finding of a lower metabolic rate for females will not influence the recommended temperatures in the existing standards. Also their study is not conclusive; they only studied 16 females at a sedentary activity. They should also have studied 16 men at the same activity to be able to compare.

“The reason why we, in some field studies, find that women prefer higher room temperature than men is attributed to the level of clothing. Women adapt better their clothing to summer conditions while men are still wearing suit and tie. So if the thermostat is set to satisfy the men, the women will complain about being too cold. In the standard, this adaption of clothing to summer is taken into account so if the standard is followed the women would be satisfied; but maybe not the men.”

ASHRAE President David Underwood notes that the standard has been continually refined and updated since it was first published in 1966, reflecting changes in the industry and new research as it becomes available.  Standard 55 is based on an earlier document developed in 1938 by two predecessor societies of ASHRAE, titled Code for Minimum Requirements for Comfort Air Conditioning.

“The standard continues to focus on defining the range of indoor thermal environmental conditions acceptable to a majority of occupants, while also accommodating an ever increasing variety of design solutions intended to provide comfort and to respect today’s imperative for sustainable buildings,” Underwood said.

Olesen notes the researchers should have consulted other studies and technical guidance.

“They should also have looked at the ASHRAE Handbook, Fundamentals, which explains the background for the standard and addresses differences between men and women, young and elderly, etc. with literature references,” he said.

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