Characterisation of domestic hot water end-uses for integrated urban thermal energy assessment and optimisation

Former integrated urban energy assessments and optimisation have modelled domestic hot water (DHW) demand as a single stream, as space heating, currently, is the main energy demand in buildings and a detailed DHW modelling was therefore not required. However, the characterisation of energy saving measures (e.g. grey water heat recovery) and the selection of optimal heating utility in buildings with low temperature space heating would benefit from a differentiation of the various DHW end-uses at urban scale (building blocks, streets, districts, city). To this end, a new method characterising the main DHW appliances in households, hotels and nursing homes at urban level, is proposed. A review of European publications characterising water uses is conducted and utility load and energy consumption equations are developed. A specific model for district heating heat exchangers without thermal storage for integrated urban energy optimisation is proposed. The DHW-related energy consumption results are confirmed by literature values in a real urban case-study. Showering represents more than 80% of the DHW energy demand, and more than 97% of the total DHW heat use is required up to 40 °C. The proposed method contributes to urban energy assessments and optimisation by improving the level of detail of the outcomes and by strengthening their integrated approach.