Measured energy consumption and carbon emissions of air-conditioning in UK office buildings

With the EU Energy Performance in Buildings Directive imminent in 2006, attention is focusing on how to reduce carbon emissions from buildings in practice. This research was undertaken to try to establish some ‘real’ buildingbased figures for the energy performance of air-conditioning systems in UK office buildings. One of the major questions to be answered is whether chilled beam and ceiling systems really are more efficient than traditional air-conditioning systems when used in the real world.1,2 This paper presents findings of a two-year field monitoring study investigating the energy performance of airconditioning (AC) systems in UK office buildings. The findings shown in this paper include: 1) the cooling power demand for the various air-conditioning systems monitored; 2) comparison of national energy consumption and carbon emissions bench-marks to the monitored systems; 3) comparison of the energy consumption and carbon emissions of reverse-cycle AC systems with traditional heating-only systems. The results show that chilled ceiling systems typically consume significantly less energy than the other generic AC types in the heating and cooling of office buildings. However, all the generic AC system types studied appeared capable of meeting current ‘good practice’ standards for energy use in the UK. Practical application: The work provides an insight into the energy performance achieved by real AC systems as operated in UK Offices. When the EC Energy Performance in Buildings Directive becomes law in January 2006 the practically achievable energy and emissions performance of building services will fall more sharply into focus for designers. It is hoped that this paper will provide information useful to both designers and operators of AC systems in the UK as they attempt to reduce the impact of AC systems on the environment.