Comparison of the solar energy utilisation potential of different urban environments

Besides a more efficient energy use, large scale application of solar energy technologies in the urban context will be necessary in the upcoming decades to achieve a drastic reduction of greenhouse gas emissions in the biosphere. Two different urban sites, representative of two of the largest Swiss cities (Basel and Geneva), were examined under this aspect 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 two urban sites will be presented in this paper. It has been observed that in both cases the values and useful surface areas appropriate to solar technologies are significant.