In order to achieve the targets for reducing CO2 emissions, energy consumption in the building sector in particular must be reduced. More than 14% of the final energy demand of private households is accounted for by the provision of domestic hot water. As part of a campaign by the North Rhine-Westphalian consumer advice centre to raise public awareness of the issue of efficiency in the supply of domestic hot water, the FfE carried out a study entitled "Energy savings potential through the optimisation of existing drinking water systems".
Initially, the energy savings and the cost-effectiveness of efficiency measures were investigated, including the use of economy fittings, replacement of the storage tank of domestic hot water and insulation of the circulation lines. Based on the derived supply structure of domestic hot water in North Rhine-Westphalia, energy and cost saving potentials to be economically achieved were determined (see Figure 1).
Figure 1: Annual fuel costs for the provision of domestic hot water in North Rhine-Westphalia calculated in the current state and after implementation of the economic measures to increase efficiency
In addition, the technical and economic potentials for the use of electricity from the company's own photovoltaic system to provide domestic hot water were analysed. For this purpose, an Excel tool was developed in which the drinking hot water and electricity requirements of a household are made more flexible by using a thermal or electrical storage tank.