Assessment of Solar Irradiance on the Urban Fabric for the Production of Renewable Energy using LIDAR Data and Image Processing Techniques

A general understanding of the solar admittance and solar gains incident on the urban fabric is very useful to assess the potential implementation of renewable energies at the scale of the city. The authors propose a tool that uses Light Detection and Ranging (LIDAR) data to automatically derive this information in a fast and accurate way with no need to refer to the construction of complex models of the urban layout. In particular, a complete methodology from the extraction of LIDAR data to the environmental analysis of urban models and the visualization of results is presented. Aim of the work is to establish a process to investigate digital urban models integrating cross-disciplinary competences, like remote sensing, GIS, image processing and urban and environmental studies. Toward this goal, working on several interfaces, tools and datasets was necessary to provide a consequent structure to the introduced methodology. Case study for application was two districts in Geneva (a historical district, and a modern one) where LIDAR data are available. The use of a hybrid approach from raw LIDAR data and vectorial digital maps (GIS data) of roofs footprints derived from a 3-D urban model of the city of Geneva allowed to interpolate a 2.5-D urban surface model (DUSM) of roofs buildings, with a resolution grid of 0.50 by 0.50 metres. This step reveals itself as fundamental for processing the environmental analysis of the urban texture. In particular, the implemented tool calculates solar radiation and solar accessibility on buildings' roofs, in order to investigate the potential for implementing photovoltaic panels.