The contribution of buildings towards energy consumption has dramatically increased over the past decade. According to the EC's Joint Research Centre, HVAC systems in Europe were estimated to account for approximately 11% of electricity consumed in Europe [1] and with associated CO 2 emissions highly contribute to global climate change. This paper deals with the electricity consumption of air-conditioning systems in buildings in the Czech Republic. The paper presents results of actual

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... ts in 15 mostly office buildings over a 5 year period. The extensive analysis of measured data is presented in graphs and tables. A considerable difference in the electricity consumptions for cooling between the various administrative buildings is identified. The advanced commissioning of air-conditioning systems and its general application in the Czech buildings is presented in the paper as well. Energy consumption measurements, proper operation and application of advanced commissioning are identified as important methods tool to reduce energy consumption of airconditioning systems in existing buildings.