Sunscapes: ‘Solar envelopes’ and the analysis of urban DEMs

The aim of this paper is twofold: first, it simplifies ‘solar envelope’ calculations, making them easier to carry out over extensive urban areas; second, the proposed routines refine the definition of solar envelopes so that they reflect more accurately the actual irradiation of the city and make results directly applicable in urban planning. Both targets can be achieved if we use a new technique for urban analysis, based on the processing of urban digital elevation models (DEMs). The second question, in particular, can be addressed by introducing the concept of ‘iso-solar surfaces’ – surfaces that extend the concept of solar envelope through energy considerations. Our early experiments suggest that iso-solar surfaces may be an effective way to quantify urban irradiation and illumination. As an example, results are presented for the Trade Fair site in Milan, Italy, one of the largest real estate developments currently being implemented in Europe.