# How much energy to heat a room, and heat pump efficiency?

1. Dec 15, 2008

### ProtoBob

O.K. this is maybe a large question.....

I am trying to find out how much energy it would take to do the work of a heat pump compressor that would be required to heat a.... lets say 10 ft. x 10 ft. room of a typical house.

I know there are a lot of variable here.....

What I am trying to discern from this, is, if there were an alternate method to drive a heat pump compressor motor, how much energy would be required to do so....

Any thoughts?

2. Dec 15, 2008

### Staff: Mentor

You're not looking for energy, you are looking for power. This is very dependent on things like insulation and climate. A good starting guess of required heating for a relatively cool climate (say, the northeastern United States) would be 10 W/sq ft. A decent heat pump has a COP of 2.5 when it is cold outside, so that gives an input power of 4 W/sq ft.

3. Dec 15, 2008

### ProtoBob

If I am understanding correctly, thats 10 watts per sq. ft. so a 10 x 10 room would be
100 sq. ft. requiring 100 * 10 watts, or 1000 watts to maintain a "typical" temperature.

Could this also be stated as 1000 watts per hour or 1kwh to maintain room temperature?

would this also be equivalent to 3413 btu per hour?

Thanks! :)

4. Dec 15, 2008

### Staff: Mentor

Could this also be stated as 1000 watts per hour or 1kwh to maintain room temperature? [/quote] There is no such thing as "watts per hour". There is watts for an hour, which is watt-hours (or 1000 watt-hours = 1 kWh). Watts is already a rate.
Yes, though note that people do a kind of short-hand and often interchange "BTU" and "BTUH". BTU is technically the rate (power, like kW) and BTUH is the energy (like kWh).