Modifying behaviour to save energy at home is harder than we think…

A 2-year study was carried out in a sample of 120 apartments in two cities in Israel, Jerusalem and Nesher, in which different strategies to influence energy consumption were tested using an interventional case-control design. Socio-demographic attributes of individual households were recorded and building thermal performance was evaluated by detailed computer simulation. Attitudes of the study participants to environmental issues were assessed to identify potential motivations for energy savings. Although year-on-year energy consumption increased for exogenous reasons in all test groups, in Jerusalem the increase in the maximum intervention group (which received detailed information on energy consumption patterns over time, and individually tailored energy-saving tips) was 2.5%, compared to 9.5% in the reference group, which received only generic energy saving tips. The difference among groups in Nesher was not significant. A multivariate analysis confirmed that the attempt to influence apartment occupants' behaviour failed to generate a statistically significant reduction in domestic energy consumption. The study underlines the importance of controlling for endogenous factors, such as weather and building thermal performance, while evaluating the effectiveness of different intervention strategies, to avoid potentially wrong inferences about the effectiveness of such strategies. We conclude that effective behaviour modification may require repeated implementation of a broad range of tools over a sustained period of time.