A ONE-YEAR ENERGY EFFICIENCY COMPARISON STUDY BETWEEN TWO WATER HEATER SYSTEMS-ONE USING A CONDENSING TYPE GAS WATER HEATER SYSTEM AND THE OTHER USING CO₂ HEAT PUMP WATER HEATER SYSTEM

Abstract

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.