The impact of the solar collectors application and domestic hot water demand on unit conventional energy consumption in multi-family buildings

Application of solar thermal collectors to support domestic hot water preparation is very common, especially in single-family buildings. However, the use of this type of installations in multi-family buildings raises many concerns connected mainly with economic performance. This issue is related, among others, with the small number of available scientific papers that presents the results of long-term exploitation studies of this type of systems. This paper presents results of three-year measurements, which were carried out in four multi-family buildings located in Poland. On the basis of conducted measurements, annual and seasonal conventional energy consumption for preparation of 1 cubic meter of domestic hot water was estimated [GJ/m3]. Moreover, the influence of hot domestic water demand [m3] on unit heat consumption for domestic hot water preparation [GJ/m3] was presented, which should be properly considered when analyzing the effectiveness of this type of system.