抄録
The authors compared the primary energy consumption and CO2 emissions of a condensing type gas water heater system with a CO2 heat pump water heater system for one year in Obuse, Nagano Prefecture, a location that experiences cold winters. The energy efficiency of the condensing type gas water heater system was 0.86, where as the CO2 heat pump water heater system’s energy efficiency was 0.68. The primary energy consumption and CO2 emission of the condensing type gas water heater system was less than the CO2 heat pump water heater system in three of the four seasons, except for summer.
