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Business, Energy, STEM

Will This New Information End The Thermostat Wars?

Digital Thermostat by Trane

Digital Thermostat by Trane

I couldn’t let this week end without saying something about the research that was released this week on why females are always complaining about being cold in air conditioned offices. I can’t think of too many females that could not relate to the thermostat wars in office buildings. I have had my share of iceberg experiences in the work environment and other places. Hearing this conversation discussed in various media this week made me smile.

Two Dutch researchers have discovered that women feel cold more readily than men. Fancy that? A small sample test suggests that women are comfortable at an average temperature of 2.5 degrees Celsius (C) warmer than men – roughly 23 vs 25 degrees C. [Ref 1] And while my actual experience would have suggested that the temperature spread is greater than about 3 degrees – maybe even as wide as 5 degrees  or more – I was more interested in knowing how they arrived at this conclusion.

As it turns out, the current indoor temperature model was derived in the 1960s. Fifty years later, we are still using this model when so much about our buildings and heating-ventilation-air-conditioning (HVAC) systems have significantly improved for the better. Also, there are more women in the workplace than when this model was developed.

The study, conducted by Dutch researchers Boris Kingma and Wouter van Marken Lichtenbelt [Ref 2], state that the empirical thermal comfort model that was developed in the 1960s is based on an average male and may overestimate female metabolic rates by up to 35%. The metabolic rate in the formula is based on a 70 kg, 40 year-old male, and does not factor in adjustments for gender or age.

The researchers suggests that the predictive mean vote/percentage people dissatisfied (PMV/PPD) model – currently the basis for indoor thermal environment design – can be enhanced to include the diversity of building occupants including males and females, children, older workers and senior citizens, and the influence of tissue insulation.

In other words, to get better thermal comfort for all occupants, the PMV/PPD model needs to be recalibrated.

As the BBC article also notes, Some people also have suggested less scientific reasons for the general gender divide over the air-con[ditioning] – while some women wear light dresses in August, some men are stuck in stuffy suits.”

Here’s the plus: a more accurate representation of thermal demand by building occupants leads to better energy consumption predictions and real energy savings. I don’t think anyone will complain about that. Factor in that body fat mass, muscle mass, and skin blood flow influence tissue insulation. This could be a game changer for hospitals and other care facilities were patients and residents are usually at a resting metabolic rate.

My most recent experience with thermostat wars occurred on a work assignment about eight months ago. Two females guarded the local thermostats like hawks and no one could get near them. Unfortunately, I was as cold in this environment as I would have been with mostly men in this office. Why? Perhaps we should ask the researchers if their predictive model includes hormonal changes.

Currently, I don’t have to worry about thermostat wars because I have been working from home lately. However, I am not taking my sweater, shawl or gloves out of my car any time soon because it remains to be seen how quickly building owners will calibrate their thermal comfort model for office work environments and other places.


1.   Air-conditioning: Why might women feel temperature differently from men?, by Who, What, Why in The Magazine, British Broadcasting Company, August 4, 2015, http://www.bbc.com/news/magazine-33760845

2.   Energy Consumption in Buildings and Energy Thermal Demand, by Boris Kingma and Wouter van Marken Lichtenbelt, in Nature/Climate Change, published online August 3, 2015, www.nature.com

About Vi Brown

Vi is principal and CEO of Prophecy Consulting Group, LLC, an Arizona firm that provides business and engineering services to private and public clients. Prior to establishing her consulting practice in 2001, Vi worked with Motorola, Maricopa County Government, Pacific Gas & Electric, CH2M Hill, and Procter & Gamble. As an adjunct faculty member, Vi teaches undergraduate calculus classes and graduate level environmental courses. She is also a professional speaker.


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