Realist evaluation of the implementation and impact of the NHS carbon reduction strategy in the UK.

Objectives: To evaluate the extent to which organisational factors facilitate or inhibit the implementation of the National Health Service (NHS) carbon reduction strategy within acute hospital settings.

Setting: A single acute NHS Trust with four satellite sites which serve more than 2 million patients annually in Central England.

Participants: Interviews with a purposive sample of 10 stakeholders, including those who conceptualised the intervention and those who were responsible for its implementation.

Intervention: The NHS is a major carbon emitter and therefore developed the 'NHS carbon reduction strategy (NHSCRS)' in 2009. NHS organisations are contractually obliged to develop a local carbon reduction strategy known as a Sustainable Development Management Plan (SDMP) which details carbon reduction measures (CRM), as described in the NHSCRS. However, the organisational context within which the SDMP is implemented is likely to determine the extent of its success. We undertook an adapted realist evaluation cycle to develop refined initial programme theories. Documents were analysed using thematic content analysis. Interview data were analysed using thematic analysis.

Results: CRM were most likely to be implemented if the Trust Board were sufficiently pressured by staff and reputational fears, and the potential impacts of CRM were perceived to align with wider organisational aims. Differences in implementation of CRM across hospital sites were related to logistical factors, accessibility to regional partners and contractual relationships. There were expected carbon, energy and long-term financial savings, with variability in the effectiveness of some CRM post implementation.

Conclusions: Organisational factors, particularly Board leadership and internal implementation pathways, have a significant bearing on whether CRM are implemented or not. However, greater national support and guidance is needed for NHS organisations to effectively reduce their carbon emissions. Further cycles of this evaluation are necessary in multiple case study sites to illuminate the path to a net-zero NHS carbon footprint by 2045.