17 ms·
More specifically, heat pumps often have a COP of around 2, even in very cold weather (-20℃). That means that for every two joules that a light bulb turns into
by mistercow 13y ago
More specifically, heat pumps often have a COP of around 2, even in very cold weather (-20℃). That means that for every two joules that a light bulb turns into heat, you will save only one joule (and less in most conditions) on your overall energy consumption.
In very, very cold areas, the COP of the heat pump will reduce to 1, and in those cases the incandescent bulb isn't wasting any energy.
- ericd 13y agoThanks for putting specific numbers to it. It's really surprisingly efficient, especially at warmer temps (0℃) which are more common in most of the US.
- mistercow 13y agoThat number is also assuming that the pump pulls from the air rather than the ground. Ground based pumps are apparently more efficient (well, energy effective; efficient is not quite the right word in this case) because the ground warms up in the sun more than the air.