If you’re female and feeling too hot or cold in the office, it could be because the HVAC system was set without regards to your physiology – and it’s leading to wasted energy on cooling and heating, according to new research published in Nature Climate Change.

The method for setting temperature for many office HVAC systems – the predicted mean vote/percentage people dissatisfied model – was devised in the 1960s and, in typical 1960s fashion, was based in part on the metabolic rate of “the average man”.

The authors of Energy consumption in buildings and female thermal demand say these methods may overestimate the resting heat production of females by up to 35 per cent, however, leading to buildings being “intrinsically non-energy-efficient in providing comfort to females”.

Researchers Boris Kingma and Wouter van Marken Lichtenbelt argue that as the built environment pushes towards more energy efficient buildings, “indoor climate standards should accurately represent the thermal demand of all occupants”, not just men.

Adjusting these standards to account for gender differences could reduce a building’s energy consumption by avoiding unnecessary levels of cooling in the summer and heating in the winter, they said.

In an experiment the researchers studied the physiology of 16 young women performing light office work. They found the women’s metabolic rate was significantly lower than the standard values, suggesting lower levels of cooling would be needed in the summer for them to feel comfortable.

“Ultimately, an accurate representation of thermal demand of all occupants leads to actual energy consumption predictions and real energy savings of buildings that are designed and operated by the buildings services community,” the researchers said.

The researchers concluded that thermal comfort models needed to “adjust the current metabolic standard by including the actual values for females”.

They said further benefits could be gained by accounting for the effects of sex, body size and scaling the associated metabolic rates to the type of activity undertaken, however more research would be necessary to clarify if that was the case.

In an accompanying News & Views article, Joost van Hoof from the Fontys University of Applied Sciences wrote: “These findings could be significant for the next round of revisions of thermal comfort standards – which are on a constant cycle of revision and public review – because of the opportunities to improve the comfort of office workers and the potential for reducing energy consumption.”

He said the energy saving benefits would also increase as climate change caused higher temperatures that would require more intense airconditioning.

However, he said because of a small sample size, a large-scale re-evaluation in field studies might be needed “in order to sufficiently convince real estate developers, standard committees and building services engineers”.

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  1. Excellent points Max and very much an echo of the recent position put forward by ASHRAE in response.

    The original story/study received some significant exposure recently, particularly through being featured in the NY Times. If only more pressing IEQ issues had such a ‘viral’ effect.

  2. As an expert in thermal comfort I found this to be quite funny. The research paper refers to the PMV/PPD index developed by Fanger in the 1970s. 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 doing the same sedentary work and wearing the same type of clothing – no differences were found 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 as they only studied 16 females at a sedentary activity; they should also have studied 16 men at the same activity as a comparison. The reason why, in some field studies, discover that women prefer higher room temperature than men is attributed to the level of clothing. Women adapt their clothing better to summer conditions (some suggest that women have more flexibility in their dress codes between seasons, especially in the corporate/business office environment) 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.”

  3. With respect to both genders this issue is the least of our worries in regard to HVAC efficiency. The fact is that most HVAC systems in place today are highly inefficient for a number of reasons including the central mechanical engineering, energy management and heat load management. As a result HVAC&R are a major and rapidly growing source of GHG emissions. This is a far more important matter.

    By all means lets manage the gender preferences as best we can but how about we recognise the GHG emissions and energy efficiency are the central issues.

  4. I can’t see how this will have any real impact. Most HVAC are temperature controlled so if the proportion of each sex changes and more or less body heat is emitted then the system will adjust the amount of cooling or heating accordingly – like it would when the number of people in a building changes. Unless the temperature set points are changed how does this have an impact? I can see a small impact on the size of the system but expect this will be trivial when compared to the day to day variables like thermostat wars, number of people, numbers of computers etc.