Understanding occupant heating practices in UK dwellings

The 2008 Climate Change Act has committed the UK government to reduce CO 2 emissions by 80% of 1990 levels by 2050. To meet this target a significant reduction in energy consumption will be required from domestic dwellings and in particular space heating which accounts for more than 50% of the energy used in the UK housing stock. The UK government has initiated a number of policies to reduce energy use from UK dwellings. Energy savings that result from energy efficiency improvements to dwellings have sometime been lower than expected as a result for the rebound effect. Discussion of the rebound effect has questioned whether these polices will result in the CO 2 reductions required to meet the national targets. Large-scale survey research has shown that energy use is related to climate, built form of properties, efficiency of heating systems, socio- economic indicators and occupant behaviour. Temperature monitoring studies have been undertaken to gain insight into how occupants heat their homes. If the variation in indoor temperatures can be explained by; (1) social determinants such as age, income and the number of household occupants and; (2) technical determinants such as house type, house age and level of insulation then this would enable energy efficiency initiatives (e.g. cavity wall installation or education programmes) to be targeted where they will be most effective. This paper presents preliminary results from a large-scale city-wide survey of over 500 homes in the city of Leicester, UK. temperature measurements were recorded at hourly intervals over a nine month period for the living room and main bedroom spaces in over 300 homes. Household data, including socio-demographic information, was collected for each household. This dataset is used to investigate indoor temperatures across house types. The results confirm that house type is related to differences in indoor temperatures. Flats have the highest average temperatures while detached homes have the lowest. To gain insight into heated periods households with average evening temperatures were identified. It was found 45% of mid terrace properties had evening temperatures below 18°C and more than a third of detached and semi detached home also had cold evening temperatures. There are a number of reasons for low indoor temperatures in dwellings during occupied periods including inefficiency of buildings and heating systems, the inability of occupants to afford heating and personal choice. It is concluded that to meet Government CO 2 reduction targets the rebound effect should be taken into account when calculating the energy savings expected from energy efficiency programmes. Further analysis is ongoing to identify how other social and technical factors relate to indoor temperatures. Multiple regression analysis will be used to identify how internal temperatures are correlated against a number of determinants including building characteristics (built form type, age, heating system type, heating controls) and household characteristics (age of occupants, income).