The Government's UK Low Carbon Transition Plan published in July 2009 covered energy use and CO2 emissions from the domestic sector. It highlights that the energy used in our homes for heating water (excluding that for heating our homes) is 25 per cent. of the overall domestic energy use.
The Environment Agency have carried out extensive research on the CO2 emissions from domestic hot water use. Their latest research suggests that annual emissions from heating water in a typical home are approximately 900kgCO2. This at the UK level these represent ~23MtCO2/yr of the 140.7MtCO2/yr attributable to energy end use in homes (including emissions from electricity use in homes).
Further information can be found in the Environment Agency report here:
The Government's Household Energy Management Strategy ‘Green Homes, Warmer Homes’, published on 2 March:
focuses on cutting carbon emissions from the household sector through energy efficiency and other measures. In developing the strategy, my Department met representatives of a variety of organisations, including Waterwise who campaign on water efficiency.