Ya'll correct me if I'm wrong
The COP is a term that has to do with the fact that a heat pump will produce less capacity at lower temps. I believe the COP is just a reference to electric heat with a COP of 1.
But, I don't think it can be related as you are trying to do. The COP is more of an output term rather than an input term. You will still be paying the same amount on your utility bill, but you won't be getting as much out.
North, this is probably more of a question myself, than an answer.
At 47 degrees, yur heat pump will be using ( pretty much ) the same electricity, but you will not be getting the same BTU's out, and the unit will run longer, costing you more money
[Edited by bornriding on 03-18-2005 at 06:20 PM]