Solurban Project, Solar Utilisation Potential of Urban Sites

Besides providing a more efficient energy use, a large scale application of solar energy technologies in the urban context will be required in the upcoming decades to achieve a drastic reduction of greenhouse gas emissions in the biosphere. Three different urban sites, representative of three of the largest Swiss cities (Basel, Geneva and Lausanne), were examined in order to assess their respective solar potential. Spatial distributions of solar irradiation and daylight fluxes over the overall building facades and roofs were calculated using ray-tracing simulation techniques to determine the appropriate placement of different solar technologies (passive and active solar, photovoltaic and daylighting). Several performance indicators were used to assess the solar utilisation potential of these urban sites (e.g. statistics of sky view factors and daylight factors). A comparison of the results observed for the three urban sites is presented in this paper. It has been observed in the three cases that the building surface areas appropriate to solar technologies are very significant.