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Solar access is a crucial factor for the wellness and comfort of building occupants and for the development of the urban fabric. Most countries implemented regulatory frameworks that aim to guarantee appropriate access to sunlight into buildings. The solar envelope is a method that allows to determine the maximum buildout volume that guarantees solar access of neighboring buildings. Computer design tools have been developed to facilitate the automatic creation of solar envelopes. However, most of the tools have limitations when complex regulations need to be taken into account. The presented research develops an alternative computational method to generate solar envelopes to be used for different ordinances and particularly efficient in dense urban environments. Results show that the proposed method permits to obtain larger building masses than the conventional method, and to automate the generation of envelope variations, useful for assessing building performance and form selection in the early design stage.
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.
Direct solar access and daylight requirements contribute significantly when it comes to shaping the layout and appearance of contemporary cities. Urban planning regulations in Estonia set the minimum amount of direct solar access that existing housing has the right to receive and new premises are required to get when new developments are built. The solar envelope and solar collection methods are used to define the volume and shape of new buildings that allow the due solar rights to the surrounding buildings, in the case of the former, and the portion of the own façades that receive the required direct solar access, in the case of the latter. These methods have been developed over a period of several decades, and present day CAAD and environmental analysis software permits the generation of solar envelopes and solar collection isosurfaces, although they suffer from limitations. This paper describes an advanced method for generating solar collection isosurfaces and presents evidence that it is significantly more efficient than the existing method for regulation in Estonia’s urban environments.
Daylight requirements are an important factor for the layout and image of cities. In Estonia complex requirements of direct solar access guarantee the right-to-light for existing and new housing buildings. Nowadays different environmental design software permits to calculate the quantity of direct sunlight hours for facades or windows and allows designers to generate solar envelopes. This is an efficient method to calculate the shape of the maximum buildable mass on a plot that allows the neighboring buildings to receive a required amount of direct sunlight. The existing method to generate solar envelopes presents a significant limitation when applied to the Estonian daylight standard. The present work discusses a method that consider specific amounts of direct solar access and take the context into account to improve the actual solar envelope generation method and available tools. The tests carried out in four different urban areas show that the proposed method is superior to the existing. It generates significantly larger size solar envelopes that fulfill the requirements with a small margin of error. The outcomes can be generalized to underline the importance to consider the requirements of specific facades when calculating solar envelopes in urban environments and the incidence of the context layout.