An energy and cost comparison of residential water heating technologies

Water heating is a significant user of energy. Several studies have investigated the development of more efficient systems. The present study compares several commercially available options for water heating and compares them with the performance of a recently developed of a gas-fired heat pump water heating system. Comparisons of each technology are conducted using annual energy use and operating cost metrics. Payback period predictions for the gas and electric heat pumps are performed with the electric and non-condensing gas storage units as a base case. Electric and gas heat pumps, at total initial costs of $2,400, are estimated to require 3.6 and 3.1 year payback periods when compared to an electric storage unit, respectively, while a gas heat pump with a total initial cost of $2000 is estimated to require 2.3 years. For this study a gas heat pump cost of $2400 was assumed. Daily total draw cases for a gas heat pump of 243, 303 and 379 L compared to a non-condensing gas storage unit as the base case show payback periods of 4, 3.2 and 2.5 years, respectively. This analysis shows that electric and gas heat pump technologies offer significant energy use and operational cost savings compared to baseline water heating technologies with reasonable payback periods.