When I was young, over 70 years ago, everyone knew that turning down the heat at night made sleeping more comfortable. And it used less fuel. One can do a quick study of kilocalories (unit of heat) that shows this.

So, I was shocked when I heard that the laws of physics had changed, and heater companies were telling homeowners not to turn down the heat at night.

An article by David Brooks, writer for the New York Times, interviewed Dr. Alexis Abramson, who has a big list of references in heating studies that says, in effect, “Wrong.”

Dr. Abramson notes that some heat pump makers say not to turn down the heat, but Dr. Abramson has not seen any data to back this up. So, maybe the old physics still work. My view of what happens is: Heat goes through wall insulation at a near constant rate (depends on the difference in temperature between inside and outside). So, if we start with 70 inside and 30 outside a kilocalorie might be lost per hour. Lower the thermostat to 60 degrees, and 0.9 kc/hr might be lost during the first half hour and then 0.9 for the rest of the night so during the 10 hours of night. So, 10 x .1 means a kc less heating was used. In the morning the heater puts out its full heat (being an on/off system) for at most 15 minutes to bring the room back to 70 degrees. That 15 minutes uses a lot less fuel than the extra needed to overcome the heat loss for that time. “Show me the data.” (Numbers used above were best guess).

So, the science of my youth still holds, and you can save fuel and money and stop heating the world by turning your heat down at night. Use blankets instead of fuel money.

Maybe a radiant heat concrete slab might take longer to cool in the evening and heat up in the morning, but no fuel is used as it cools, and the heater can put out only so much heat at a time.

Turn your heat down at night. Save money, fuel and the earth.

Peter Grant

Bristol