20 September 2011
We designed and built an office building which does not use HFC/HCFC for air-conditioning system. This is the first heat pump system using natural refrigerant only in Japan. This system uses ammonia as refrigerant for air-conditioning and carbon dioxide as
refrigerant for water heating, utilizing geo-thermal through foundation piles in the ground. In addition employing two-pipe dynamic ice transportation system, which were developed from one-pipe system, realized higher thermal efficiency of the whole building.
According to the analysis of operation data after completion, the COP of air-source heat pump is 3.0 to 3.5 at cooling mode and 2.0 to 2.5 at heating mode while the COP of watersource
heat pump utilizing geo-thermal is 3 to 7 at cooling mode and 4 to 8 at heating mode. We collect and analyze the data using BEMS (Building Energy Management System) on
operation of the system, and BEMS made it possible to do the fine tune control promoting the energy savings of this office building. For example controlling volume of fresh air flowing into the system precisely enables us to
achieve effective air circulation and energy savings.