Heat Pumps for Cold Climates (Emerging Technologies) (Report‪)‬

The majority of air-source heat pumps (ASHPs) are installed in moderate to warm areas of the United States, mostly south of the Mason-Dixon Line. Two major issues make conventional ASHPs unattractive as a heat source in cold climates. First, buildings in colder climates often have appreciably smaller design cooling loads than design heating loads. Second, ASHP heating capacity and coefficient of performance (COP) decrease as the outdoor temperature, [T.sub.o], decreases because the temperature lift across the compressor increases. For these reasons, conventional ASHPs sized to meet cooling loads cannot meet the full heating loads at lower [T.sub.o], necessitating extensive use of costly, and energy-inefficient, electric resistance heating.