Oh, how the news media love the “thermostat wars” between men and women. It’s a good source of stories based on conventional wisdom and the occasional (faulty or incomplete) research paper. The utility companies want in on the action, too. I’ve seen television ads for gas companies trying to convince viewers that just switching fuels will eliminate the battle over the thermostat. But do women really need warmer temperatures than men?
Decades of research on thermal comfort
Guess what. The idea that men and women have widely different internal thermostats is dead wrong. Let’s clear this up with the summary from the ASHRAE Handbook of Fundamentals. Based on many decades of research, they say:
The experiments show that men and women prefer almost the same thermal environments. Women’s skin temperature and evaporative loss are slightly lower than those for men, and this balances the somewhat lower metabolism of women. The reason that women often prefer higher ambient temperatures than men may be partly explained by the lighter clothing often worn by women.
The image above of two newscasters talking about the “Battle of the Thermostat” couldn’t make the point any better. The man is wearing a button down shirt, tie, and coat (and probably an undershirt as well) while the woman is a wearing a sleeveless blouse or dress.
Six factors of comfort
ASHRAE’s thermal comfort standard lists six factors that affect our comfort. They are:
- Metabolic rate
- Clothing insulation
- Air temperature
- Radiant temperature
- Air speed
The first two are personal factors. Metabolic rate is a measure of your energy use. Recall that your body is a heat engine, turning fuel into mechanical energy and heat. It’s similar to a power plant turning fuel (e.g., coal or gas) into heat that spins a turbine that generates electricity. Not all the heat can turn into usable energy, however, so a human body and a power plant both must deal with that excess heat somehow. Remember, you need cooling! And the higher your metabolic rate, the more cooling you need. Your metabolic rate depends on the nature of your particular body—everyone is different—and on your activity level.
Clothing, of course, insulates the body from its surroundings. In winter, that’s a good thing. In summer, it can slow down the body’s cooling process. We all know that when you’re too warm, you can take off excess clothing to cool off. No mystery here.
The last four are environmental factors and don’t affect men any differently than they affect women. The ASHRAE statement above makes that clear.
So, the next time you’re in a room with a man who happens to feel warmer than a woman, don’t automatically jump to the conclusion that it’s simply because he’s a man and needs lower air temperatures to feel cool enough. When you account for all of the factors of comfort, both personal and environmental, the research is clear. So, do women need warmer temperatures than men? No.
Note: If you’d like to dive into this topic and really learn how to apply the principles of thermal comfort to buildings, get yourself a copy of Robert Bean’s free book, Thermal Comfort Principles and Practical Applications for Residential Buildings. (Yes, it’s free!)
Allison Bailes of Atlanta, Georgia, is a speaker, writer, building science consultant, and the founder of Energy Vanguard. He has a PhD in physics and writes the Energy Vanguard Blog. He is also writing a book on building science. You can follow him on Twitter at @EnergyVanguard.