Here in the mid-Atlantic and Northeast, the temperature has been getting up into the high 90’s (Fahrenheit) in recent days, and the forecast is calling for 2 to 3 days with highs at or above 100 here in Delaware. What is the best way to set your thermostat for air conditioning when the weather is this hot outside? In this post I will demonstrate that setting the thermostat higher in hotter weather will not only save energy and money (which is obvious), but is also better for your health and enjoyment of life.
To illustrate why this is true, I will start by sharing an amusing story about Texans.
Texans and Air Conditioning:
I grew up in Lancaster, Pennsylvania, which has humid summers with occasional hot spells up into the upper 90’s. But these hot spells are not the norm. The climate overall is quite temperate, and it is common for people, like me, to grow up without air conditioning. During these few hottest days of summer, we slow down, avoid heavy exertion during the heat of the day and stay indoors or in the shade, drinking cool drinks and maybe using a fan.
Texans pride themselves on being bold and courageous. One summer, I took a vacation to Austin, Texas, which, at the time, was the farthest south I had ever been. The sun was much brighter, and the days were hot, all in the 90’s. But I was shocked to find that Texans were wimps about the heat. They complained that it was too hot out even early in the day, when it was still in the 80’s, and when it was dry heat. Why were these “tough” Texans such cowards about the heat? Because they all were used to having air conditioning virtually everywhere. They had never learned to adapt, and never allowed their bodies to adapt to the heat either.
The Human Body Adapts to Heat & Cold:
The human body, like most biological systems, has a remarkable ability to adapt to different conditions. Humans have lived for thousands of years in virtually all parts of the globe, from tropical rainforests to the driest deserts to frigid polar areas and everything in between. People who work outdoors in the deep south do not complain when faced with a modestly warm, 85 degree day in the mid-Atlantic, the same way someone from Alaska, Maine, or Minnesota doesn’t complain when the temperature drops below 20 degrees. But in order to allow yourself to adapt, you need to actually expose yourself to the weather. If you set your thermostat to 68 degrees in the summer and stay indoors most of the time, when you step outside into 85 degree weather, it’ll feel like a sauna. If your thermostat had been set at 80 instead, you’d walk outside and it would feel a little bit warm.
Remember to stay adequately hydrated:
It is very important in hot weather to drink enough water, and if you are sweating a lot, to replenish your electrolytes by eating something that naturally contains some sodium and potassium. Dehydration is the main health risk associated with very hot weather; imbalance of electrolytes is less common but is still an issue in very hot weather.
Adapting your behavior to the heat:
In addition to your body adapting on its own, there are easy ways to make the heat more tolerable. People in the northern U.S. often make fun of southerners because they walk so slowly, but slowing down is one of the best ways to keep cool. Drinking cool drinks, and wearing light, loose-fitting clothing that breathes well (like cotton or linen).
The best way to set your thermostat is relative to the outdoor temperature, not at a fixed temperature:
When it is 90 outside, try setting the thermostat at 80 or higher. If it’s 95-100, try setting the thermostat at 85 or higher. If you use a window unit without a temperature gauge, you can still use the suggestion below of inching the setting cooler gradually.
Turn your A/C off when you leave your house or apartment, and close the blinds to keep the sun from heating up the interior. When you return, if it’s too hot, inch the temperature down 1 or 2 degrees at a time until you feel comfortable. This allows you to keep the temperature as high as possible. You may be surprised at how much a difference of as little as 2 degrees Fahrenheit makes: air conditioning also dries out the air, so if you are coming in from a humid outdoor environment, the same temperature in an air-conditioned interior will feel much cooler.
Setting the thermostat very low (68 or 72 as some people do) in the hottest weather is not only costly and wasteful of energy, but it also is hard on your body and will keep you from appreciating the outdoors during hot weather. Like the Texans described above, you risk becoming a wimp about the hot weather. If instead you pick a more moderate temperature, you will not only be conserving energy (and saving money) but you will feel less of an adjustment when you go outdoors in the summer–and you will be more ready to appreciate outdoor activities, whether you do them in the heat of the day or during the cooler periods in the morning or evening.
What can you do?
- Spend some time outdoors in the hottest weather (staying adequately hydrated!), to allow yourself to adapt to the heat. You may find that the more time you spend in the heat, the less cool you need it to be indoors in order to feel comfortable.
- Try experimenting with inching your thermostat or A/C settings down gradually from whatever interior temperature you are starting with, instead of just setting it at a cold, fixed level. You may be pleased both with your savings on the electric bill, and your increased ability to enjoy the outdoors during hot weather.
- If you are in charge of an office environment, consider setting the thermostat higher on the hottest days; make the dress code allow options for weather-appropriate clothing (shorts, skirts, sandals, short sleeves) on these days even if you require less casual attire on other days. Let people know ahead of time what the interior temperature will be so they can plan accordingly. If you are not in charge of the thermostat or dress code, voice your opinion to those who are in charge, and let them know that you would appreciate a more moderate indoor temperature in the interest of health and sustainability.
- If stores, classrooms, or other indoor public spaces are too cold, let people in charge know, and encourage them to set the temperature to a more moderate level in the hottest weather.