The role of individual metering in reducing domestic hot water consumption in residential buildings: A long-term evaluation

Within the residential sector, Domestic Hot Water (DHW) production represents the highest energy-intensive end-use after the space heating. Energy consumption for DHW production in residential buildings depends not only on the efficiency of the production, distribution and supply systems, but also on the occupants’ behaviour and characteristics. For this reason, it is crucial to increase users’ awareness in order to induce virtuous behaviours and reduce excessive uses of DHW. In this context, individual metering and consumption-based billing can be extremely useful and low-cost tools for reducing energy and water wastes and increasing the end-use energy efficiency in buildings. This paper is aimed at investigating the effect of individual metering systems on DHW consumptions in the residential sector. For this purpose, the operating parameters of 16 substations of a high-temperature district heating (DH) network supplying 137 multi-family buildings were monitored daily for over 14 years, during which individual DHW meters were installed and consumption-based billing was introduced. It has been found that after the installation of individual DHW meters the average daily heat consumption for DHW production decreased by 14% and that the DHW volume withdrawn by the buildings decreased by 32%. Those variations were found to be statistically significant.