Hospitals are significant contributors to natural resource depletion and environmental change. Our objective was to establish the extent to which hospital environmental sustainability has been studied and the key issues that emerge for policy, practice and research.

The PubMed, Engineering Village, Cochrane and King's Fund databases were searched for articles relating to hospital environmental sustainability published in English between 1 January 1990 and 1 October 2013. Further studies were found by review of reference lists. One hundred ninety-three relevant articles were found and 76 were selected for inclusion in the review.

Common research themes were identified: hospital design, direct energy consumption, water, procurement, waste, travel and psychology and behaviour. Some countries (particularly the United Kingdom) have begun to invest systematically in understanding the environmental effects of hospitals. We found large variability in the extent of the evidence base according to topic. Research regarding the architectural fabric of hospital buildings is at a relatively mature stage. Similarly, there is a developed research base regarding devices and technologies used within hospitals to reduce the environmental effects of direct hospital energy and water use. Less is known about the clinical, psychological and social factors that influence how health care professionals use resources, travel to/from hospital, and interact with the buildings and technologies available. A significant part of the environmental footprint of hospitals relates to clinical practice, e.g. decisions regarding the use of pharmaceuticals and medical devices. Medical ‘cradle to grave’ life cycle assessment studies have been published to understand the full financial and environmental costs of hospital activities. The effects of preventive or demand management measures which avoid unnecessary hospital procedures are likely to be much greater than incremental changes to how hospital procedures are performed.

There remain significant gaps in the evidence base on hospital sustainability. Assessments of environmental impacts and natural resource use are beginning to be produced, both at the level of individual hospitals and at the health system level. These are an important start, but in many areas do not yet provide sufficiently detailed information to guide decision-making. There are many areas where the interests of patients and the environment coincide, but others where tensions exist. Rising resource costs and climate change mitigation measures are likely to create an increasing stimulus for research on hospital sustainability. Such research will benefit from inter-disciplinary coordination across research funders and countries.