Using building management system data to reduce energy use and improve maintenance visibility in acute hospitals: a review, national data analysis and practical framework for NHS estates

Acute hospitals are among the most energy-intensive public buildings, and most already have a building management system (BMS) whose data are used mainly for basic control and alarms. This paper reviews evidence on using BMS data to reduce energy use and improve the visibility of maintenance needs in hospitals, and analyses national Estates Returns Information Collection (ERIC) data for English acute trusts from 2023/24 to 2025/26. Acute trusts used 10.07 TWh in 2025/26, 76% of it as heat. Energy intensity across 215 general acute hospital sites varied almost twofold between the 10th and 90th percentiles (310–591 kWh/m²) and was not associated with estate age (Spearman ρ = 0.04, p = 0.60). Studies in commercial buildings report median savings of 3% from energy information systems and 9% from fault detection and diagnostics; applied to acute trusts, these rates suggest 0.30–0.91 TWh, £32–95 million and 55–165 kt CO2e a year. Hospital evidence centres on operating theatre ventilation setback, and evidence linking BMS data to maintenance management is limited. A six-stage framework is proposed covering data checks, schedule optimisation within HTM 03-01, alarm rationalisation, fault-to-work-order links and verification. Evaluation in NHS hospitals is needed.