Heat loss from non-circulating domestic hot water pipes increases water consumption and energy demand

Abstract

Hot water use in showers is a major contributor to residential water and energy consumption, and associated costs and carbon emissions. This study aims to quantify how heat loss from non-circulating pipes contributes to water and energy consumption in residential showers. Heat loss from pipes was modelled for detached dwellings in Melbourne, Australia, using Monte Carlo analysis to quantify variability. Sensitivity analysis was conducted to identify key factors contributing to heat loss. This is the first study to quantify the variability of the impact of heat loss from pipes into increased water (and hence energy) consumption in showers. Under Melbourne conditions, we predicted that heat loss from pipes contributes approximately 2 to 10 % in average shower hot water consumption. Longer pipes, smaller diameter, longer showers and longer intervals between showers were the primary factors driving additional hot water consumption.