Effective use of a ground-source heat-pump system in traditional Japanese “Kyo-machiya” residences during winter

Today, promoting abundant renewable energy use, such as heating system using ground-source heat, has become imperative. The preservation of traditional wooden dwellings unique to Kyoto called Kyo-machiya has recently become a priority policy in Kyoto, Japan. However, due to their poor airtightness and thermal insulation, Kyo-machiya dwellings require considerable energy to heat during winter. Most Kyo-machiya dwellings have a well from which residents are supplied source water for drinking, washing and other purposes. Well water can potentially be harvested as a heat source, providing a comfortable, low-consumption indoor environment during winter months. In this study, an experiment was conducted to examine the practicability of installing simple ground-sourced heat-pump systems in the existing wells of Kyo-machiya dwellings. A heat pump system comprising an indoor unit and outdoor unit was installed near a well in a Kyo-machiya dwelling. Antifreeze solution was circulated in a pipe that passed through the well water. The heat captured from the water was returned to the heat pump. Heat gain from the well water was calculated from the measured temperature and the flow rate of the circulating antifreeze solution. Furthermore, an analysis model reproducing the experiment is suggested to examine the efficient operation of the heat-pump system.