Solar constraints as a guiding principle for urban form: a case study applied in the context of the Distrito Federal (Brazil)

Abstract The urban form influences buildings’ access to the sun, interfering in the levels of radiation (irradiance), daylight (illuminance) and energy production potential. Hence, one must consider the proper use of solar energy in the design of the urban form. This study aims to optimize urban forms based on the use of solar energy in buildings, considering the maximisation of irradiance on the roofs, and at the same time, the minimisation of irradiance and reception of a satisfactory level of illumination on façades. The study was applied in the Administrative Region of Gama (Distrito Federal, Brazil), subject to the Land Use and Occupancy Laws (LUOS). The method is a simplification of Martins, Adolphe and Bastos (2014) and includes the classification of the urban fabric, using ArcGIS; the calculation of the solar performance for 67 scenarios, using both DIVA and Grasshopper software; and an analysis, with irradiance and illuminance criteria, to define optimised urban forms. The results show that it is difficult to achieve satisfactory levels of illuminance on façades in lots that are small, close together and with high occupancy rates. Seven optimised forms were obtained, highlighting the need to review the LUOS parameters. The study concludes that the design of lots (size, spacing, orientation) and their integration with occupancy parameters (occupancy rate and number of floors) is highly relevant in urban planning. The method is feasible and can be replicated in different conditions.