The effect of water demand management in showers on household energy use

This paper explores the range of potential energy use impacts of shower water demand management in a case study of five highly characterised households in Melbourne (Australia), and assesses the difference in energy and cost responses for four different hot water system types. Results show that a shift to four minute showers (from current durations of between six and ten minutes) would lead to a reduction of between 0.1 and 3.8 kWh p−1 d−1 in the households studied, comprising between 9% and 64% of baseline hot water system energy use. Contrasted with an average energy use for water service provision in Melbourne of 0.3 kWh p−1 d−1, such household reductions demonstrate significant potential for urban water cycle energy management. Combined water and energy (natural gas) cost savings in response to the four-minute shower scenario were $37 to $500 hh−1 y−1 in the households studied. Energy cost savings would be more significant for households with electric storage hot water systems than those with gas systems, at $39 to $900 hh−1 y−1, due to higher variable tariffs for electricity than natural gas in Victoria ($0.2678 kWh-1 vs $0.0625 kWh-1). Households with electric storage hot water systems may therefore have greater financial incentive to participate in water-related energy demand management (assuming similar tariff structures).