Dr Wokje Abrahamse of Otago University and Dr Lauren Christie of Victoria University of Wellington present their views of research theory and engagement principles. Wokje introduces the theoretical barriers to change and discusses the results from a systematic review of 38 studies to determine the effect of interventions designed to conserve household energy use. Given the findings from her PhD research, Lauren introduces five key principles that should be used when designing interventions to encourage the uptake of energy efficiency technologies. Both Wokje and Lauren conclude that in each and every case, 1 – the specific barriers to change for that target group and problem need to be understood first, and 2 – that a combination of approaches should be used.