Energy requirements and solar availability in suburban areas: the influence of density in an existing district

Urban sprawl is a major issue in terms of sustainable development. In fact, low-density suburban neighbourhoods represent a significant contribution to the overall energy consumption of a territory for energy needs in buildings and for transportation. But, although the environmental impacts of urban sprawl and their associated energy consumptions are now well documented, it remains a concern in many regions. This phenomenon is particularly familiar in Belgium, where 52% of the building stock is composed of detached and semi-detached houses, predominantly located in low-density suburban districts (contained in a range between five and twelve dwellings per hectare). In the current context of growing interest in environmental issues, local authorities become aware of this concern and are now trying to limit the development of new low-density suburban districts while households still continue to promote dispersed individual housing types located outside city centres. In this context, the paper proposes to investigate the influence of an increase in built density, in existing suburban neighbourhoods. The idea is to favour a higher built density in existing neighbourhoods instead of building new low-density neighbourhoods on unbuilt areas. The impacts of four renewal strategies dealing with the density are assessed, at the neighbourhood scale, for three indicators: (1) the potential energy savings for heating houses, (2) the solar energy received by the facades and roofs, as dispersed individual housing types are known to be those that receive most solar gains and (3) the potential area of land savings. The influence of insulation, climate conditions and orientation is finally discussed. The chosen case study is a typical Belgian suburban neighbourhood. Research tools are numerical simulations tools and dynamic thermal modelling software. The results of this exercise show that it is theoretically (land property is not take into account in our analyses) possible to increase built density in existing suburban neighbourhoods. Energy savings are significant while solar energy received by facades and roofs remain huge. Insulation is a critically important factor. Moreover, increasing the built density in existing neighbourhoods allows to preserve unbuilt areas and to limit the need for new infrastructures and networks, which should help suburban areas to become more sustainable.