Toward Low Energy Cities

Within the framework of sustainable development, it is important to take into account environmental aspects of urban areas related to their energy use. In this article a methodology is proposed for assessing residential energy uses for buildings and transport at the city scale. This method is based on the use of geographic information system (GIS) tools combined with a statistical treatment of urban and transport criteria. The methodology allows us to model building and transport energy use at the city scale, as well as to consider the possible evolution of city energy consumption and to simulate the effects of some strategies of urban renewal. An application is given to study different energy management strategies for the urban area of Liège, Belgium. Building and transport energy consumption are compared at the city scale and their possible evolution in the future is highlighted. Forecast scenarios on future energy policies for Liège's building stock show that the European Directive on the Energy Performance of Buildings and even more selective energy policies applied only to new buildings are not sufficient to widely decrease building energy consumption at the city scale. Renovation of the existing building stock has a much larger positive impact on city energy consumption reductions. The methodology developed in this article can be adapted or reproduced for many other urban regions in Belgium, but also in Europe and even further.