Abstract: A detailed energy audit is carried out for a complex of 6 office buildings in Brussels (Belgium) representing over 30 000 m² of occupied space. The results show very high energy consumption for both heating and electricity. Detailed computers models are created of all 6 buildings and calibrated based on real consumption, monitoring results from Building Energy Management Systems, actual occupation profiles and real meteorological data for Brussels.

Based on the dynamic simulation model, a series of measures to increase the energy efficiency of the buildings are then proposed. A technical and economic analysis which evaluates the environmental impact and payback time of each measure is carried out. The objective of the study is to reduce energy consumption of existing buildings by 30% while keeping improvement measures economically interesting.

Results show that energy savings of 27% are feasible with an overall payback time of approximately 3 years. This approach confirms the high potential for energy savings in existing office buildings, which could be applied at large scale in large cities and urban areas in China.

Keywords： dynamic simulation – building operation - energy performance