Domestic hot water consumption pattern: Relation with total water consumption and air temperature

Abstract

From a sustainable development perspective, reducing hot water consumption poses the opportunity for increasing water and energy efficiency simultaneously. Comparing with the research on total water and water end-use distribution, quantitative data on domestic hot water consumption and understanding/modeling the drivers underlying its use is scarcer. More importantly, since total water consumption is frequently measured at a household level, estimating the portion that is used as domestic hot water would allow a simpler modeling approach than accounting for all the factors affecting water consumption in general, and domestic hot water consumption in particular.The present research effort aims at providing insights on domestic hot water consumption in households by using 3 years of cold and hot water monthly records from around 10 300 apartments divided by 500 buildings spread over 3 regions of Belgium. In addition to the expected seasonal variation, the proportion of the water consumption used as hot water was found to vary between 28% and 36%, on average. Also, domestic hot water consumption variation was found to be strongly correlated with the outside air temperature. The results presented provide a simple tool to estimate the order of magnitude of domestic hot water consumption knowing the total water consumption.