A novel solar envelope method based on solar ordinances for urban planning

Solar access requirements constitute a significant aspect for the performance of buildings and for the image of cities. The solar envelope is a method used during the schematic design phase to determine the maximum volume that buildings cannot exceed to guarantee good access to direct sunlight in streets and on neighboring facades. However, two major shortcomings exist that prohibit the use of existing solar envelope techniques in practice: They don’t include the neighboring buildings in the overshadowing calculation, and they utilize a fixed start-and-end time inputs for the selection of specific hours of direct solar access. Different direct solar access ordinances exist that require that new buildings do not obstruct direct sun light in existing dwellings: (1) during specific hours, (2) for a quantity of hours, (3) as a fraction of the actual solar access. For the second and third type of ordinances no existing solar envelope methodologies exist. The research presented in this paper develops a computational method that increases the efficacy of the generated solar envelopes including the context in the calculations and provides the possibility to select the quantity and quality of sun light hours, and thus allows the modeler to generate solar envelopes optimized for different objectives. The method aims to help architects and planners to design environmental conscious buildings and urban environments.