We review the existing evidence on interventions for energy poverty and health with a novel and distinctive focus on how interventions work to produce health outcomes. There is a substantial literature on the impacts of interventions for energy poverty on health, most of which is concerned with substantial energy renovations, and focused on measuring health outcomes. Here we offer a distinctive analysis of this material: using a combination of realist review and process evaluation we use the evidence to articulate the ways in which interventions work. We focus on substantial energy renovations for health, given most of the existing evidence refers to these. Our analysis allows us to identify the logic of intervention design, showing how the practicalities of implementation are shaped by causal assumptions, as well as documenting how participants respond to these interventions. The analysis reveals gaps between intervention design and participant response, which suggest that interventions must work closely with participants to ensure success. Policy recommendations include: energy poverty interventions should take account of how people will respond to technical change, fund support for households to adapt to new technology, offer opportunities for inclusive design processes, and be flexible in delivery.