Assessing greenhouse gas emissions in hospitals: The development of an open-access calculator and its application to a German case-study

Hospitals are major contributors to climate change. It is therefore essential to identify the main sources of hospitals’ greenhouse gas (GHG) emissions to develop and monitor mitigation measures. Yet, a transparent and comprehensive hospital-specific GHG accounting methodology is currently lacking. We have developed a hybrid methodology that follows the GHG Protocol Corporate Accounting and Reporting Standard to calculate emissions. We used bottom-up approaches to scope 1 and 2 and, where feasible, to scope 3. Due to data scarcity, we used top-down approaches for several scope-3-categories. As a case study demonstration, we applied this methodology to a German university hospital: Scope 3 accounted for the majority of GHG emissions (164,529 t CO₂e (71%)), while scopes 1 (6008 t CO₂e (3%)) and 2 (60,565 t CO₂e (26%)) contributed less. Methodological challenges remain, such as a limited accuracy and monitoring options for top-down approaches. Nonetheless, this case study demonstrates that the developed methodology supports hospitals in measuring GHG emissions as part of their regulatory requirements and responsibility to safeguard planetary health.