Impact evaluation of low flow showerheads for Hong Kong residents

Abstract

The voluntary Water Efficiency Labelling Scheme (WELS) on showers for bathing in Hong Kong is a water conservation initiative of the Hong Kong Special Administrative Region (HKSAR) Government. As shower water consumption has been identified as a potential area for carbon emissions reductions, this study examines, from a five-month measurement survey of the showering practices of 37 local residents, a range of showerheads with resistance factors k = 0.54-4.05 kPa· min2· L-2 with showering attributes including hot shower temperature, temperature difference between hot and cold water supply, flow rate and water consumption and shower duration. A Monte Carlo model is proposed for evaluating the water consumption and carbon-reducing impacts of WELS on showers for bathing at confidence intervals with input parameters determined from the measurement survey. The simulation results indicate that full implementation of WELS rated showerheads with k ≥ 4.02 can reduce water consumption by 37%, energy use by 25% and carbon dioxide (CO2) emissions by 26%. This study is also a useful source of reference for policymakers and practitioners to evaluate the impacts of water efficient showerheads on water consumption, energy use, and CO2 emissions.