OPTIMISATION OF THE ENVIRONMENTAL AND FINANCIAL COST OF TWO DWELLINGS IN BELGIUM

A four-year project (SuFiQuaD) has started in 2007 to optimise the sustainability of the Belgian dwelling stock, focussing on the environmental impact, the fi nancial cost and the qualities. The whole life cycle of represen-tative housing types is assessed and recommendations for improvement are formulated. The environmental impact is evaluated through a life cycle assessment and is expressed in monetary terms, while a life cycle cost analysis is executed for the fi nancial evaluation. A multi-criteria analysis is used for the quality evaluation con-sidering aspects as for example size of rooms, available wall length for furniture and acoustical performance. For the optimisation the Pareto principle is used, searching for the highest life cycle cost reduction for the smallest investment increase and for the highest quality increase for the lowest life cycle cost increase. This paper elaborates on the developed methodology and the results of the implementation to two dwellings (results of the fi rst phase of the research). The analysis reveals that it is feasible to obtain a large reduction in the life cycle environmental cost for only a minor extra fi nancial investment and life cycle cost. Furthermore, fi nancial-based decisions prove to differ from environmental-based ones. For the case studies, internalisation of the environmental cost leads to an average increase in investment cost of 8%; while the maintenance cost (including cleaning and replace