Reducing hospital electricity use: an end-use perspective

Hospitals are an energy intensive building type for which high energy costs and sector carbon targets increasingly prompt attempts to reduce operational energy use. But evidence is sparse and generic one-fits all solutions are problematic due to the complexity and the differing specifications of hospitals. This study therefore focusses on departments as unit of analysis. Five department types (operating theatres, laboratories, day clinics, imaging departments and wards) with differing energy intensities, operating hours and at different stages within the patient pathway are investigated across three case study hospitals of different building age and size (11 departments in total). Detailed audits of installations and use are undertaken to attribute measured departmental electricity use to different end-uses. It is found that lighting loads are dominant in low energy intensity department types, while intensive department types have high loads for specialist ventilation and laboratory equipment. Resulting energy reduction strategies consequently need to take account of these differing challenges, for which an analysis of contributing factors as suggested for example by CIBSE TM22 proved useful. The use of floor area weighted operating hours is proposed as metric for hospitals and other complex buildings which may be beneficial in understanding end-use contributions to total energy use and in highlighting the after-hours switch off potential of building parts in otherwise continuously operating environments