Conditioning the Problem: I’m Cold, You’re Hot

By Nate Goore, Principal and Signo Uddenberg, Director of Research, Design & Innovation

The issue of thermal comfort has been gaining media attention. Some articles have argued that we over air-condition our spaces, citing that the U.S. is the world’s leader in air-conditioning, and Americans prefer an average temperature of 70, which is considered chilly by European standards.[1] Others examine the gender divide over thermal comfort, theorizing that females tend to be colder in the workplace because they dress  seasonally fashion-wise and weather-wise whereas their male co-workers sport businesswear with little seasonal variation. [2]

Not one of the above cited articles actually focuses on the fundamental question: What is comfort? The current conversation focuses on air temperature, the accepted proxy for comfort.

Air conditioning allows us to create sealed interior environments with constant temperatures and humidity levels. Air conditioning has conditioned us to feel uncomfortable whenever interior conditions move outside of a narrowly prescribed band. U.S. Department of Labor’s Occupational Safety and Health Administration recommends that businesses keep their temperatures set at between 68 and 76 degrees Fahrenheit, with humidity between 20 and 60 percent [3].

So why don’t we feel uncomfortable before a roaring fire, on a brisk winter walk, or at the beach under the summer sun? All of these conditions put us outside of our prescribed comfort zones.

The answer is expectations. Psychology plays a determinative role in setting our expectations for comfort

Where you were and what you were doing prior to the immediate moment affects how thermally comfortable you feel. Did you just walk for five minutes from the parking lot into a building on a 95° F day? In direct sunlight or in the shade? With a cooling breeze or without any respite from the heat? Were you walking or running?

If you were running, your metabolic rate would be closer to 8  MET (metabolic equivalent of task) as opposed to  MET if you had leisurely walked. Metabolic rate affects your sense of thermal comfort from an internal heating perspective. It is the heat you create (in addition to mechanical energy) when performing an activity and consuming the body’s fuel. The more active you are, the higher your metabolic rate. The more heat you produce, the warmer you feel.

Imagine you are playing soccer. Weather conditions are 85° F with 75% humidity. The game is tied up, and you are focused on scoring. Running around, your metabolic rate is 6 – 8 MET. You are likely hot and sweating, but with your focus on the game, your teammates, your opponents, and the remaining time on the clock, your thermal comfort doesn’t even cross your mind.

Now, imagine that it’s 85° F with 75% humidity. You are in a cramped classroom listening to a less than engaging lecture that seems like it will go on forever. Your metabolic rate is around 1 MET. All you can think about is how miserable you feel. The same goes for sitting through your fifth meeting of the day or working on that TPS report (Office Space anyone?).

A number of cold-climate cultures follow a nightly routine of taking extremely hot baths before bed. Comfort is maintained through the cold night by means of a planned prior activity, which minimizes the need for mechanical heating.

Physical exertion is not the only prior activity that impacts how we perceive the relative thermal comfort of current conditions. Sleep lowers the metabolic rate, which translates to lower internal temperatures. A restful night sleep makes you find normal conditions comparatively cooler. Spicy foods increase internal temperatures while cold foods cool them down. Proper hydration regulates body temperature, leaving you less prone to overheating or underheating, as the case may be.

Our expectations for comfort and how that comfort will be provided shape our perception of comfort. When the hot water is running low in the shower, you feel cold even though the water is over 100° F. If your iced tea is over 40° F, it feels warm when you drink it. And we even seek out environments, like steam rooms and saunas, expressly for their thermal properties, which are outside of what is considered comfortable

We have been conditioned to expect air temperatures between 68° and 72° F. Accustomed as we are to air conditioned houses, schools, offices, and shopping centers engineered for a theoretical man’s comfort. temperatures outside of the range trigger a trip to the thermostat or a complaint. Studies have shown that the AC is kept running even when natural conditions are comfortable. Instead of turning the AC down or off, the reflex is to throw on a sweatshirt, all the while wasting precious energy.

Thermal comfort is far more than a simple matter of air temperature and mechanical climate control. Thermal comfort is a system that involves the interactions between the natural environment, cultural norms, and our individual physiology, psychology, and activities.

Expanding our thermal comfort zones (and break the energy-hungry cycle of conditioned environments), calls for us to consider the other factors in the system. Actively modulating the sequence of conditions is one way to recondition our expectations. Another is to avoid air conditioning as a remedy for an uncomfortable situations, like boredom or social awkwardness, that has nothing to do with temperature is another.

And yet another is to gain an appreciation for the culturally diverse responses to thermal comfort. The Bedouin, along with other desert cultures, drink hot tea which generates sweat to cool the body down. The Finnish have a tradition of ice hole swimming; cold-water immersion is a positive shock that gets the blood circulating to paradoxically warm up the body (and release pain-relieving and pleasure hormones to boot).

A siloed solution that targets just one of these factors misses the opportunity to address thermal comfort in a holistic way. One that doesn’t just mitigate the perceived thermal discomfort, but that promotes a healthier, more vibrant lifestyle.

 

[1] Washington Post: “Europe to America: Your love of air conditioning is stupid”

[2] Washington Post: “Frigid offices, freezing women, oblivious men: An air-conditioning investigation”

[3] Washington Post: “How America fell in love with crazy amounts of air conditioning”

 

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