Adapted strategy for large-scale assessment of solar potential on facades in urban areas focusing on the reflection component

The objective of this paper is to propose an adapted method of calculation to evaluate the solar potential on building facades on a large scale. Autonomous electricity supply is nowadays an important issue, particularly during the winter. Thus the facades of buildings, which are better irradiated in winter than the roofs, can provide a response to this issue. Research has been focusing for several years on fine modeling of radiative phenomena in an urban environment. The first challenge is to obtain a physically realistic model considering the phenomena of local reflections. The second challenge is to succeed in implementing this type of simulations on large scales. These two issues are antagonistic: the first implies making the model more complex while the second implies simplifying it. This paper proposes a calculation strategy to reconcile the two issues based on a simplified radiosity method. The results obtained via this strategy were compared to those obtained by measurement and simulation on a theoretical canyon. Subsequently, this calculation strategy has been deployed to real districts in Geneva, Switzerland.