抄録
Three houses in Hokkaido that have CO2 heat pump water heater for cold regions were investigated from the view point of its energy saving, and its more efficient usage. The coefficient of performance (COP) of heat pump in a house with a smaller amount of hot water consumption and with a hot water tank installed in a cold garage shows much lower value. It was proven that 2.2〜1.7, total COP became 1.8〜1.0 for COP of annual heat pump simple substance.
