Reduce hot water use to curb emissions

A new report from the Energy Saving Trust and Environment Agency warns that hot water use could soon account for more than 70% of domestic carbon emissions.  Currently, emissions from space heating in existing housing far exceed that from water heating; but if improvements in the energy efficiency of new homes are not combined with advances in water efficiency, this situation could be reversed.
Although the Government’s Low Carbon Transition Plan highlights the urgent need to curb UK greenhouse gas emissions, little attention has been paid to the carbon footprint of water use. Six per cent of the UK's annual carbon emissions is related to water use, with nearly 90% of that from hot water use in the home.

The study also found that despite the introduction of water-saving technologies and sustainability standards for new homes, our love of power showers means that on average we are still using about 150 litres per person per day – the same amount as ten years ago. In fact, although the Code for Sustainable Homes is designed to reduce both energy and water consumption, it has created loopholes that can lead to higher carbon emissions from domestic water use even though the volume of water used remains the same. For example, the calculations allow savings from greywater recycling to offset increased water use through higher flow showers. This would result in higher emissions because the showers use hot water as opposed to the systems that use the recycled greywater, which is cold.  

The report recommends that planners and developers should include water efficiency measures in energy-efficiency retrofit programmes to save water and energy and in turn reduce emissions. It also calls on the Government to review the regulatory framework for hot water system design so that it is as demanding as that relating to building and ventilation design. Consumers are urged to reduce their carbon footprint and save money by making simple changes, such as washing dishes in a bowl rather than under a running hot water tap.

The Energy Saving Trust study was published in the same week as the House of Commons Select Committee report on balancing sustainable water supply with affordability. This recommended that Ministers should consider a “water efficiency obligation” to prevent worsening water scarcity in the South and East of England.

‘Quantifying the energy and carbon effects of water saving’ – the summary and full technical reports can be found here. The Energy Saving Trust will build on this work by undertaking a pilot study with advisory group Waterwise on how energy and water efficiency advice can be integrated.