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Water consumption in sustainable new homes (NF29)

Overview

One of the measures of sustainability in the Code for Sustainable Homes and its predecessor, EcoHomes, is the quantity of water used by consumers living in new homes. Changes to Part G of the Building Regulations in England and Wales aims to bring down average water consumption from 150 to 125 litres per person per day, but what is the success of these design targets?

This report looks into the average water use in seven homes built in accordance with the Code or EcoHomes.

Summary of content

The Code for Sustainable Homes (“the Code”) is a national standard that aims to create homes that are more sustainable and reduce CO2 emissions. The Code measures the sustainability of a home against nine categories including internal potable water consumption and external water use.

A pilot study has been carried out to monitor water consumption in dwellings built to Code specifications to compare it with values predicted by the Water Calculator in the Code, in order to assess whether the targets in the Code are practical and achievable.

Seven properties in which families lived normally were tested: five dwellings constructed to the standards of the Code and two to meet those of EcoHomes. Water meters were fitted and the actual water use was measured for a period of between 6 and 12 months.

The study has shown that actual water consumptions in the dwellings on average exceeded the designed maximum water consumption targets set in the Code. Although some improvements in water efficiency have been achieved, installing water efficient fittings and appliances as specified in the Code has only a limited effect on minimising water use.

Consumer behaviour and attitude play a substantial role in reducing water consumption. Further research is needed to examine the impact of consumer behaviour and attitude on reducing water consumption through mitigation measures such as metering, awareness raising, and setting caps on water use. A linear correlation between CO2 emissions and utility bills has been observed, which indicates that reduction in water consumption may help to reduce CO2 emissions, as well as lowering energy and water utility costs (this may not be the case where very low targets dictate the use of grey water recycling and/or rain water harvesting).

This study can also be used to assess the impact of Code water targets on reducing water consumption in new homes.