Measured Hot Water Consumption in Appartment Buildings as Key Design Parameter for Solar collector Installations

The increasing number of solar collector installations for larger appartment buildings proves that solar thermal energy is a favourable option for this type of water heaters. When operated in a preheat-mode such installations can reach a high collector loop efficiency which - besides the lower specific costs of material and installation - provides additional cost benefit. However, there may be a substantial decrease in collector loop efficiency which causes a reduction of solar yield when the actual hot water consumption stays far behind the design value. Therefore it is important to review the available data of hot water consumption in appartment buildings.
The present contribution presents and reviews recently measured hot water consumption data from various appartment buildings at different locations in Germany. The objects represent a broad choice of different design situations, varying e. g. in the number of appartments, the size of the appartments, the specific number of occupants per appartment and the social environment of the occupants. The locations comprise urban and rural dwellings. The data very recent (the earliest data taken in 1992) and therefore reflect today's lifestyle.