By the way, shouldn't it be called "heating day degrees" rather than heating degree days? I'm aware of how HDDs are calculated, but let's say the average temp on a particular day is 50. That means that there were 15 heating degree days on that DAY. How can you have X number of DAYS in any one particlar day? Wouldn't it make more sense to say that there were 15 heating day DEGREES on that day?
The nomenclature would then reflect the fact that the temp of your house was 15 DEGREES below the avarage temp for that DAY.
I've always wondered about that.
