The energy efficiency of privately rented homes is poorer than that of owner-occupied homes in many countries across Europe, North America and Australasia. This causes wasted greenhouse gas emissions and discomfort, illness and, in extreme heat or long-term cold, even fatalities. Small-scale private landlords are the key decision-makers for energy efficiency improvements in most rental properties. Research to date has focused on economic explanations for landlords’ energy efficiency behaviour, particularly the split incentive between landlords, who bear costs of retrofitting, and tenants, who benefit from those retrofits. However an emerging stream of research proposes that a wide range of psychological, dwelling-related, and situational factors influence landlords’ energy efficiency retrofit behaviour.