Should i leave the front door open in winter?
Alan B| Posted inEnergy Efficiency and Durabilityon
I’m in Canada near Toronto. I have a south facing front of the house and have noticed that on sunny days the space between the front door (steel with foam core) and the storm door (aluminum/glass) is very hot, according to my IR thermometer about 50-65C (hand burning). This while the outdoor temperature is about -10C, inside temp 22.5C.
Should i leave the steel/foam core front door open to get some free solar heat or is the loss of air/conductive losses going to outweigh the heat gained?
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When you say the glass is hot, is that when the steel door is closed? If so, that alone doesn't tell you much. You're solar heating a very tiny space between the two doors, so a lot of that heat is going to get reflected back onto the glass. If you leave the door open and it still feels warm, then it's probably safe to assume you're gaining heat. The ambient air in the house cannot give up heat to a surface with a higher temperature. This assumes the storm door is reasonably well sealed.
Actually its the exterior steel door skin that is hot on the sun facing side.
And yes when both are closed.
You might get a benefit by opening it. A problem might be that the air leakage of the storm door might be enough more than the main door to counteract the benefit.
My blower door test was done on that door so i have no idea what its air leakage is. Plus the main door would have been closed anyways if they had used another door.
I did think about the air leakage yesterday when i tried it, though i don't mind some air exchange since it was relatively warmer than the last few weeks (and i had used my gas stove earlier anyways, so some fresh air was a good idea)
I have heard that some door companies won't warrant their product if installed with a storm door because the excessive heat can lead to failure. I don't think I've read those warranties myself but I tend to not pay a lot of attention to warranties anyway.
If it's relatively warm outside and the storm door is reasonably well sealed, you would probably have a net benefit from leaving the entry door open. But the colder it is, and the worse the air seal (or the windier it is outside), the higher the risk of a net heat loss. Radiant warmth is deceptive and can fool us into thinking we're getting a net benefit when really we aren't. (Fireplaces, e.g.).
Interesting about the lack of warranty. Frankly it makes some sense, in summer it gets so hot i leave the window of the storm doors open until fall. I forgot to take some IR temp readings in summer but i will try that this year.
I have wondered how to determine if there is a net benefit, as you say it could be deceptive.