Abstract
Few householders have the time or motivation to systematically weigh up all the facts when judging the energy consumption of their household appliances. It is likely that they instead rely on simple heuristics such as the size heuristic, which has been reported in a small number of previous studies. The studies showed that people’s perceptions of the size and energy consumption of appliances were positively correlated but the studies differed in their methods and effect sizes. The present study re-tests the use of the size heuristic using two methods of data collection (between-participants and within-participants) and three methods of correlation. On average, correlations between size and energy estimates were moderately strong but they (and the accuracy of the energy estimates) varied greatly between individual participants. Understanding householders’ perceptions of energy is vital to designing more effective energy-saving policies. The findings highlight the importance of choosing and clearly reporting methods.