Beyond the flow rate: the importance of thermal range, flow intensity, and distribution for water-efficient showers

Kemi Adeyeye,Kaiming She,Inês Meireles

doi:10.1007/s11356-019-07235-y

Abstract

Studies show that user behaviours have not necessarily changed, despite the prevalence of water-efficient products in the market. One reason is because the technical emphasis for delivering the water use efficiency of products has focused on reducing the flow rate. Therefore, this study was undertaken to examine the physical parameters that define the technical efficiency of showerheads against the experiential performance (and therefore the satisfaction with the showerheads). These parameters were measured in a controlled laboratory environment and the findings were triangulated against user feedback from in-home trials. Synergies between the laboratory data and user feedback were found. Notably, it was found that water spray intensity, distribution, and temperature loss all impact the quality of showering experience. These factors also influence shower duration—and thus the volume of water used in the shower. Significantly, these technical metrics affected the overall experiential performance of such products from the users’ perspective. Therefore, the design of water-efficient showerheads, in addition to delivering water discharge savings, should avoid poor spray distribution, intensity, and heat retention. The implications of the findings are that water efficiency labelling and product standards should extend beyond the emphasis on limiting the flow rates—typically to 9 l per min for showerheads. This study shows good merit for including the spray intensity (pressure), distribution, and degree of heat loss, in addition to the discharge rate, as part of the performance and efficiency considerations of showerheads.

Highlights

IntroductionAs opposed to water conservation, is the optimised use of water commensurate to need
Water efficiency, as opposed to water conservation, is the optimised use of water commensurate to need
This study focuses on showerheads because studies have shown that they contribute up to a third of domestic water use and the associated energy use

Summary

Introduction

As opposed to water conservation, is the optimised use of water commensurate to need. This implies that water must be optimally used and waste eliminated through behaviour, technology, and infrastructure efficiency This paper is a substantially updated version of a summary conference paper presented at the Water Efficiency Conference 2018, held from 6–8 September at the University of Aveiro. This paper focuses on the technical and not ‘allocative’ efficiency of water (Global Water Partnership (GWP) Technical Committee, 2004). Reductions in water consumption can defer investments in the expansion and upgrade of water supply infrastructure as well as the reduction of average and peak effluent loading to the wastewater system (Vieira et al 2017). The adoption, installation, and appropriate use of water-efficient devices are seen as an effective means to promote water use efficiency for the following reasons (Millock and Nauges 2010): Water consumed through both indoor and outdoor appliances e.g., showers, toilets, washing machines, sprinklers, represent a significant share of households’ daily water use in developed countries

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