What is the potential for incorporating low-energy ventilation and cooling strategies into the design of new hospitals? How would such strategies cope with a changing climate? Natural ventilation is promoted by the UK National Health Service (NHS) in its recently launched carbon reduction strategy. NHS energy targets are reviewed in the context of UK national and international targets. Examination of the targets suggests customary environmental design strategies for new hospitals will not deliver the performance required. Perceived barriers to the implementation of more naturally driven environments in healthcare buildings are discussed, particularly the risk of air-borne cross-infection. Environmental design propositions for specific clinical and non-clinical space-types are created, catalogued, and aggregated into a typical plan component, their ventilation and energy performance modelled and factored to the scale of a 200-bed hospital to current NHS service delivery policies. The exercise suggests 70% of net floor area of small-to-medium-sized acute hospitals could be naturally ventilated. A hybrid ventilation strategy may serve a further 10% of net floor area. Patients and staff may benefit from more naturally sustained environments. Indications of the predicted comparative energy performance, potentially reduced to 38 MJ/100 m3, and capital and life cycle costs are provided.