I've noticed over the past months a lot of people looking to save on energy bills in the winter, and a couple pieces of advice that show up repeatedly that I consider flawed. Not necessarily that they are outright wrong, but there are significant caveats left out.
Closing Vents to low occupancy rooms:
This one seems natural, why heat a room I don't use. There are two possible issues here.
First, you may create a moisture or mold issue. Your homes's air has much more moisture than cold winter air. When indoor air hits a sufficiently cold surface (like a window, or even a cold part of your ceiling) it will condense into droplets. When you close a room off, many surfaces may become condensing surfaces. These might be visible or invisible such as in your attic.
Second, by closing vents, you create back pressure in your forced air hvac system. Your blower motor will work harder to push air into your remaining open vents. This can cause early failure of very expensive piece of equipment. Edit: this is not usually true. See discussion from the former furnace contractor below.
Humidifying your home:
By all means, if low humidity is causing health issues or discomfort, humidify (moderately). It does not really get you free 'warmth'. We all associate muggy summers as being extra hot (because sweating no longer evaporatively cools you as well). But this does not make humid air in winter warmer. In fact, humid air has higher heat capacity, meaning more thermal energy is required to raise the temperature 1 degree. Ironically dehumidying your home with a dehumidifier consuming 800 watts of electricity, will generate MORE than 800 W of thermal heat (compressing water vapor into liquid water in the bucket releases heat). So you get 800 W heat from the appliance + heat from the phase change.
Electric Space Heaters are all 100% efficient:
In a sense this is correct, all electric heaters generate the same amount of heat inside the thermal system that is your room. However, not all space heaters will heat YOU the same amount. Efficient space heaters deliver the maximum amount of heat to YOU, and minimize heat directed to the air in your house. Many good space heaters produce infrared light. This light does not warm the air as it travels, but it does interact warm various solid objects it hits (such as your skin, or surfaces you touch). In other words, you can dump 800 watts of heat into the air and hope it warms you before it leaks out of your home OR you can dump 800 watts of heat into warming you directly. This is also why various designs might be better at aiming this infrared at you.
Love you all, stay warm. My best tips for actually saving money to be included in the comments.
Edit: I live on the border of a very cold climate zone. u/Burritogoals is correct that my advice may be incorrect in other climate zones. Do consult a building science expert before undertaking major projects such as airsealing. They will keep you from damaging your home, health, or wasting money on low return projects.
January 08, 2021 at 11:23PM
