Researchers tested the performance of three air source heat pumps in Southeast communities. We were interested to find that the actual efficiency of the heat pumps could be higher or lower than the manufacturer specs, depending on Alaska’s unique conditions. For instance, in colder weather the heat pump needs to go through more defrost cycles to prevent ice from forming on the coils, which reduces its efficiency. On the other hand, if the heat pump is running at its optimal load for most of the winter, it can actually achieve a higher efficiency than its rating. Overall, we found that 29 out of 30 heat pump owners were happy with the appliances.