The resort of low potential energy for buildings heating and preparation of domestic hot water (DHW) are discussed in this paper. Real heat pump system, which was designed and mounted for individual house heating and DHW preparation, was analyzed. The purpose of this research was to explore the seasonal factor of performance for heat pump. Manufacturer and salespeople claim that the coefficient of performance (COP) for their offered equipment is 4.5 or even higher. They also calculate the energy transformation through the entire season referring to it. Actually, it is likely that the COP cannot be used when calculating the seasonal energy transformation in reality. Electricity that is seasonally consumed and the heat that is produced in all the period should be analyzed in this context. The results of this exploration show that the real seasonal factor of performance is 3.02. With reference to experience of financial support for that type of heating systems in various European countries, there is a great necessity to create similar support schemes in Lithuania. The methodology of assessing the seasonal heat pump’s factors for performance also should be prepared in Lithuania.

Article in Lithuanian