In urban areas, the climatic loads on buildings are uneasy to evaluate. So the urban microclimate study and the determination of its impact on buildings energy consumption and comfort can provide valuable information. In this paper we show how a simplified method for radiant interchange determination can be used in solar energy study. The good agreement with the radiosity method allows one to use this simplified method in the street can-yon case. This method is then introduced in a zonal model of the street simulations, performed with variable climatic conditions show case where solar energy is the only driving force in the street air movement displaying the interest of such approach.