In this paper we explore the potential applicability of evidence of health-enabling effects of elements of the built environment – particularly access to nature – deriving from research in healthcare facilities to evidence-based design in the custodial context. Drawing on comparative qualitative research conducted in the UK and the Nordic region, we argue that although available data lack direct comparability, there is evidence that access to nature generates the same health-enabling effects in custody as are recognised in healthcare facilities. Reflecting on the differing political contexts of imprisonment in the two study areas, we conclude by advocating further research both to better understand health-enabling elements of the custodial built environment, and to better enable robust findings from healthcare facilities to be applied in custodial contexts.