Solar energy on building envelopes – 3D modelling in a 2D environment

•SEBE adopts a 2D modelling approach to derive 3D irradiances on walls and roofs.•Vegetation is shown to be essential when modelling irradiances for wall surfaces.•The overall performance of the model is high, both for roofs and walls. A new model, Solar Energy on Building Envelopes (SEBE) for estimating shortwave irradiance on ground, roofs and building walls is presented. SEBE adopts a 2D raster modelling approach to derive 3D irradiance information, which makes it possible to compute extensive areas up to city scale. High resolution digital surface models (DSMs) are used to describe the urban geometry and additional DSMs including 3D vegetation structures can also be incorporated. Inclusion of vegetation is shown to be essential when modelling irradiances for wall surfaces within the urban environment. To obtain a detailed description of input forcing conditions, the model utilizes observed hourly data of shortwave radiation as meteorological input information. The model is evaluated for a tilted roof as well as for a wall location in Göteborg, Sweden. The overall performance of the model is high, both for the roof and wall evaluation point. Application of the model is exemplified by 3D visualisation and city scale model output presentation.