CO{sub}2 payback time assessment of a regional-scale heating and cooling system using a ground source heat pump in the Nishi-Shinjuku area

摘要

We present an assessment of a regional heating and cooling system around the Nishi-Shinjuko area of Tokyo, Japan to estimate the CO{sub}2 payback time that air source heat pumps are replaced with a ground source heat pump system. Transportation of equipment sets for cooling tower, underground heat exchanger materials, digging loads, and transportation loads incurred by installation of GSHP system in place of an air source cooling system were calculated as CO{sub}2 emissions. The total CO{sub}2. emission from the installation was estimated to be 67,701t-CO{sub}2, with 87% of the CO{sub}2 emissions occurred from digging. CO{sub}2 emissions from operation were estimated from total energy efficiency and the heating and cooling demand in Nishi- Shinjuko area. Using the ground source heat pump system, 33,935t-CO{sub}2 will he emitted in one year. We estimate that the air source heat pump system results in an annual CO{sub}2 emission rate of 73, 454 t-CO{sub}2, so using the ground source heat pump system results in a savings of 54% of the CO{sub}2 emissions, 39,5l9t-CO{sub}2, in one year. Icrom these results, the CO{sub}2 payhack time is assessed to he 1.7 years for changing the heat pump system in the Nishi-Shinjuko area to the ground source heat pump system.