Solar energy potential on roofs and facades in an urban landscape

• Method to determine solar potential of an urban landscape.
• Takes into account both roofs and facades.
• Digital elevation model from LiDAR data.
• Calculates shadow for direct light and sky view factor for diffuse radiation.
• Facades have a significant impact on the urban solar potential.

A solar 3D urban model was developed for the calculation and visualisation of the solar energy potential of buildings, integrating the potential of roofs with that of facades. To assess this potential, a digital surface model (DSM) of the urban region was built from LiDAR data and a solar radiation model based on climatic observations was applied. A shadow algorithm was developed in order to calculate shadow maps and sky view factor both for roofs and facades at once. Direct and diffuse solar radiation was then obtained for each point on the ground, roof and facades with a spatial resolution of about 1 m and a time resolution of 1 h. This method was applied to a case study of the Campus of the University of Lisbon. Results show that the irradiation reaching facades is lower than that of the roofs, as expected, but due to the large areas concerned, facades have a significant impact on the solar potential of buildings in an urban area.

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