Carbon Footprint (Scope 2) and Energy Intensity per Activity in Intermediate-Complexity Hospitals in the Community of Madrid: Panel Analysis (2016–2024)

Hospital buildings account for 60–80% of healthcare sector electricity consumption, yet robust causal evidence on the relationship between building energy efficiency and emissions per unit of clinical activity remains scarce. This study applies within–group fixed effects estimation to an unbalanced panel of 12 intermediate–complexity hospitals in Madrid, Spain (2016–2024; N = 107 hospital–year observations), controlling for activity volume and exogenous shocks. Cluster–robust standard errors and Wild Cluster Bootstrap inference address the limited number of cross–sectional units (N = 12). We propose a methodological correction for the artificial 74.6% discontinuity in Spain’s electricity emission factor (2020–2021) caused by regulatory change. The within–hospital building energy use intensity (EUIe) coefficient is β = 0.646 (p < 0.001), remarkably stable across six robustness specifications (range: 0.599–0.648; 8.2% variation). Wild Cluster Bootstrap confirms statistical significance despite 75% larger standard errors. A 20 kWh/m2·year EUIe reduction achievable through Heating, Ventilation and Air Conditioning (HVAC) retrofit in 1980s–era buildings translates into 13 kWh/stay savings, equivalent to 216 tCO2/year for median–sized facilities (8.2% reduction). Within R2 exceeds 0.97 across all specifications. Building envelope and HVAC retrofit constitute the dominant structural intervention for hospital Scope 2 emissions reduction. Facilities with EUIe > 150 kWh/m2·year should be prioritized for energy efficiency interventions using NextGenerationEU funds.