04 July 2008
Japan consists of five main islands: Hokkaido, Honshu, Shikoku, Kyushu, Okinawa and other smaller islands. The country extends from the sub-frigid zones in the north to the subtropics in the south, with average annual temperatures varying from 6.4 oC in Wakkanai-city (Hokkaido) to 22.4 oC in Naha-city (Okinawa). This report describes two examples of a traditional and a modern low-energy house with two heat pumps for space heating and hot water supply in Hokkaido, Japan. From the heat source point of view, it has been confirmed that ground heat source and exhaust air play very important parts, and are very effective in the cold region. Design of an integrated heat pump system for space heating, hot water supply and ventilation, with a heat recovery unit and also a humidity control device, is expected shortly.