This paper aims to investigate the energy performance of a fitness/leisure centre. A detailed energy audit has been conducted to determine the energy consumption of the building. Through the collection and analysis of data, the energy performance and Energy Performance Indicators (EnPIs) have been identified. This research indicates that an energy audit can lead to identifying significant energy savings potential in a building. Energy saving opportunities have been identified with a potential to save 158,906kWh of electricity, 81,201kg of CO2 and potentially saving up to e51,230 per annum. A combined heat and power (CHP) plant could yield savings of up to e28,522 annually. A lighting upgrade offers potential savings of 122,976kWh of electricity and e19,373 annually. Due to their high energy demand, commercial buildings have the potential for significant energy savings. The fitness centre was built in 2004 to a high standard and is a well maintained building. Nevertheless, this paper demonstrates the significant potential for energy reduction in buildings such as fitness centres.