Abstract

The prediction of the utilisation potential of solar energy for both passive and active applications is usually based on tabular or analytical methods that use averaged irradiation data.

These methods allow the user to get results only at specific points and are nearly useless when applied to urban sites, since the complexity of urban geometries and inter-reflection and shadowing effects cannot be accounted for easily.

Recently, some Radiance based procedures have been proposed in order to obtain high dynamic range (HDR) images capable of quantifying solar access reliably and taking into account sky anisotropy, inter-reflection and shadowing phenomena and hourly or sub-hourly sequences of irradiance/irradiation data.

For this purpose, a Radiance based software package has been developed by the authors and applied to a real case of urban planning in Palma di Montechiaro, a historical town located in Sicily (Italy), in order to estimate photovoltaics and solar heating systems economics.