Abstract
This thesis explored householders' perceptions of energy consumption and saving using novel methods and drawing on cognitive theories of categorisation and heuristics. Judging the energy consumption of household appliances is difficult; judging the effectiveness of energy-saving measures even more so. The research in this thesis proposed, and found support for, a model in which householders try to simplify energy judgements using heuristics. In heuristic energy judgements, people substitute energy consumption or savings with easier-to-access features of appliances and measures. For example, inferring high energy consumption from appliances that produce heat, and high energy savings from measures that reduce heat production. Part I: A systematic literature review of the small amount of existing heuristic energy judgements research identified a common assumption that heuristic feature substitution underlies energy judgements, but there were gaps in how the theory explains energy judgements. A novel theoretical model was constructed using established cognitive theories of categorisation and heuristic judgement making. Mixed methods were used to identify existing and novel heuristic cues used in energy consumption judgements, including the size and heat production of appliances. The heuristic elicitation design and other correlational methods were compared. The difference in coefficients from different methods underlined the importance of selecting appropriate methods for the research question and clear reporting. Part II: Mixed methods were used in a novel exploration of the heuristic cues used in energy savings judgements, including heat reduction, appliance consumption, usage reduction, and measure frequency. A paired comparisons study design enabled a novel multidimensional analysis of heuristic energy savings cues and how they are used. Part III: Householders intuitively try to simplify their energy judgements using heuristics. Giving them more information is unlikely to help. Interventions to help people save more energy need to be designed to work with, not against, the heuristic cues they intuitively use.