Implementation of solar energy in urban planning

Abstract: Urban planners lack knowledge of how solar potential of buildings is affected by the decisions taken at an early design phase. Therefore, the solar potential metric SAFARn was analysed and the development of a tool for assessing the solar potential of buildings for integration of photovoltaic panels was studied in order to provide architects and urban planners with necessary information regarding solar energy. The research investigated where the most suitable building surfaces to generate solar energy are and how this is affected by the building size, shape and the surrounding building context. The study was based on residential buildings located in Malmö, Sweden. The results showed that for such a location and climatic conditions only the roof and the facade surfaces that have orientation close to the absolute south can be considered suitable. The building shape, size and urban surroundings demonstrated to be determining factors for the potential for solar energy generation. Considering the surrounding context, the results suggested that wider streets allow more solar radiation to reach the buildings. Additionally, the facades are very susceptible to overshadowing, so the dimension of the street and the height of the neighboring buildings really determine how well can the facade be used for harvesting solar energy. On the other hand, the roof solar potential is generally less affected by the surrounding layout. Investigating the neighboring buildings’ facade materials with different light reflectance properties showed that high reflectance materials increase the solar radiation on the examined building’s surfaces. Other less reflective surfaces showed to have a slightly negative effect on the irradiation. Finally, a large potential for locally produced solar energy was identified. Moreover in this study, a building assessment tool for solar energy design based on the program Grasshopper was developed in order to assist urban planners to take more informed decisions during early design stage. The tool proved to be capable of providing predictions about the amount and the location of a building’s suitable area, placement and size of the solar energy system, as well as the amount of electricity that the system can produce and subsequently how much of the building’s electricity need can be covered. The tool was also able to provide adequate visual and numerical feedback on the results. In order to fulfill the aims of this study, necessary parameters and settings regarding urban metrics, threshold values for solar irradiation that falls on the building surfaces had to be prepared for carrying on with simulations. Moreover, a step-by-step workflow of the simulations was introduced, describing all decisions and the arguments for them. The findings of this study can be beneficial to achieve a higher solar potential when buildings or urban districts are planned and buildings’ shape, height, dimension of the streets and other aspects are decided. Architects and urban planners will benefit from using the solar energy assessment tool by being able to quickly and precisely assess their proposed design and see how a potential solar energy installation will perform.