In 1991 the UK Audit Commission produced energy performance indicators for hospitals based on the type of care provided. However, an analysis of over I 00 hospitals throughout 1he United Kingdom has found the type of care provided to have relatively little effect on rhe energy performance of hospital . Although other factors influenced energy use to some degree, the major factor affecting performance was found to be the plan of the hospital, as this influenced the amount of mechanical ventilation required. Modern mechanically ventilated hospitals were found to typically use 40% of their total electricity consumption in fan power, equating to 80 kWh m-1 purely due to fans. This paper presents a suggested set of new performance indicators based on the percentage of floor area which is ventilated mechanically.