MODELING THE DESIGN OF URBAN FABRIC WITH SOLAR RIGHTS CONSIDERATIONS

A model for the design of urban grids and fabric with solar rights consideration taken into account is presented. The model allows the generation and evaluation of the building configurations, preserving the solar rights of each neighboring building, as well as the open spaces among them. The model presents a nomogram of the maximum available volume in which it is possible to build without violating the solar rights of any existing building, as well as the designed one. This volume is determined by two envelopes; the "Solar Rights Envelope" and the "Solar Collection Envelope" that are defined in this paper. We call this volume the "Solar Volume". The nomogram of the solar volume allows the determination of the preferred urban street orientation, proportion, and geometry to assure solar rights to each building and to the pedestrian sidewalks, in winter, as well as shading them in summer. The method is demonstrated by a case study. The results show that it is possible to achieve a high urban density quarter without violating solar rights. INTRODUCTION During the conceptual design phase of urban quarters, the designer deals with different geometrical characteristics related to the building's height in relation to the orientation and width of the open spaces and the pedestrian sidewalks. These include the determination of the proportion of the buildings, the open spaces and land subdivision. Each one of these topics is complex by itself, and the determination of the best design solution becomes specially complicated due to mutual influences. For example, the size of the open spaces influences the exposure of the buildings to winter sun, or can create the required summer shading. Clearly, this interrelation depends on the geometry of the buildings along the streets and the open spaces and the distance between them, as well as the geometry of the streets and the open spaces. The aim at this stage is to achieve a design that will assure the exposure of the building's elevations and the pedestrian sidewalks to the sun during a desired period in winter. Moreover, the design should guarantee their protection from the undesirable summer sun. The design of urban quarters, without considering these factors from the very beginning may cause discomfort conditions inside the buildings, in the sidewalks and in the open spaces. The importance of proper shading design was recognized by researchers more than forty years ago (Olgyay and Olgyay, 1957). The energy crisis of 1973 accelerated the attempts to find good CAD methods and tools for the design and evaluation of shading solutions on one hand and for proper insolation on the other. We can classify these CAD models according to the following categories: a. CAD tools for the determination of proper shading devices. b. CAD tools for the proper design of the open spaces between buildings regarding insolation, shadings, and the determination of solar rights. Both tools categories can further be classified into generation tools and evaluation tools. The generative design tools aid to define the proper geometry. Some early examples are; Shaviv (1975, 1984a), McCluney and Sater (1984) for the design of sunshades, Arumi (1979), Shaviv (1984b) for solar rights and the design of the open spaces between the buildings. These tools generate nomograms that present all possible solutions to a given problem. These nomograms are called "Solar Envelopes". The evaluation tools, on the other hand, analyze the performance of a given design. Some examples are; Rogers et al. (1978), Reeves (1986), for evaluating the performance of shading devices, Smith (1978), Schiler and Greenberg (1980), Kroner and Abrey (1985), McPherson et al. (1985), Peckham (1988), Dupagne (1988), Kunic (1988), Goretzki (1989), Trijssenaar (1991), Yezioro and Shaviv (1994) for evaluating solar rights and the design of the open spaces between the buildings.