What have residents got to do with it? : Variations in energy use and energy-related behaviours in single-family houses

Sammanfattning: To achieve global energy goals, energy use in residential buildings must decrease. The implementation of technical measures is crucial but alone it is not sufficient; residents need to change their behaviour as well. However, households are not a homogeneous group in terms of their energy use and behaviour; rather, the use varies between households and over time. To promote energy savings in buildings, these variations need to be explored. The main objectives of this thesis were therefore to examine how energy use in single-family houses varied and how energy-related behaviours of households influenced the use of energy. The examined energy variations included changes over time, differences between households and variations of energy use throughout the day. The impact on these variations from the residents' activities and everyday behaviours was studied as well. A partially multidisciplinary approach was employed, whereby the following methods were combined: energy data analyses with interviews, energy performance measurements with calculations, and time-use diaries with energy measurements. A literature review was also conducted. The participating households lived in electrically heated, detached, single-family houses, built in Sweden in the 1980s. The residences spanned three different housing areas, each of which encompassed similar houses.The thesis showed that on an aggregated level, the energy use was stable over years of occupancy. An individual household's energy usage could, however, both increase and decrease over time, depending on several activities occurring over the years. On a group level, the daily electricity load curves differed between weekdays and weekend days, with clear power peaks in the morning and evening on weekdays. That is, during these peak hours the households contributed to potential power deficits in the energy system. Large differences between similar houses' energy use were demonstrated, similar to findings in other research. Differences of a factor of two to three between the highest and lowest energy usages were discovered; for water use, the differences were even greater, namely a factor of six. The studies found that there were many ways to be a high or a low consumer. That is, most of the households exhibited a range of different energy-related behaviours contributing to their energy use. In addition, there was a spread between households in how long they performed various activities. Moreover, the thesis showed a parallel use of electronic devices of the same type, which meant that each household member owned their own set of devices, potentially leading to an increased use of electricity at the household level.The findings in the thesis are of value when measures are designed to encourage residents to save energy and reduce power peaks. By field measurements, the empirical studies provided technical and resident-related information that is useful when estimating and verifying energy use of buildings. Additionally, the thesis contributed to the field of multidisciplinary research on household energy use as both technical and social perspectives were in focus – an approach that not only attempted to measure actual energy data, but also to reveal the behaviours that were concealed behind the data.