Daily Archives: January 24, 2013

When it’s 8F

It’s been cold for a change. Getting down to single digits (6F, 8F) at night.

1) When it’s 8F, that’s 33% colder than a more typical 23F.

(If you assume a 68F temp in the house. Outside temps of 23F is a differential of 45F. When it’s 8F, that’s 60F difference. And 60F is 33% more than a 45F diff.)

2) When it’s 8F, that’s similar to it being 138F.

(In both cases it’s a 60F difference vs my desired inside temp. Summer=78F, Winter=68F. Well, not exactly, since in the winter-time the electric appliances, sun and people and pets in the house are helping keep the house comfortable, and in the summer they are making things more difficult (when the house is closed up because it is very hot and humid outside. Plus our heat pump is a lot more efficient at cooling than they are at heating. I know they (even the fancy h2i hyperheat heat pumps) get down to like 2x COP/efficiency when it is cold. But when they are cooling, I believe mini-split air-source heat pumps often have SEER ratings of over 20. And SEER (EER) = COP * 3.412. So COP=6. So from the heat pump’s perspective, it’s different.)

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