Solar Access and Zoning

Thursday, April 18th: 1:15-2:45 PM

Solar access zoning + building information modeling

Authors: Karen Kensek, Alicyn Henkhaus
Presenters: Alicyn Henkhaus, University of Southern California, Los Angeles; Sara Bronin, Alicyn Henkhaus, Karen Kensek, Catherine Roussell, AIA, John Reynolds, FAIA, Edna Shaviv

Abstract: Architects choose how to incorporate sunlight into their designs, often for day-lighting or renewable energy. However, future access to the sun is often controlled by the decisions of other architects building on neighboring sites. Solar access zoning, one method of protecting solar rights, ensures that a building does not shade its neighbors for a specified time period each day. A solar envelope represents the largest volume that satisfies the conditions of solar access for the building’s neighbors. This does not imply that a building within the envelope’s spatial limitations is an energy-efficient design. Rather, when applied to adjacent lots, solar access zoning guarantees that each lot receives enough sunlight to take advantage of passive and active solar design strategies. The geometry of the solar envelope is relatively difficult to calculate; it depends both on spatial relationships between the sites, and on the daily and seasonal path of the sun. Solar envelopes can be constructed as physical models with a heliodon or generated by various digital tools. Each tool reflected the current technology of the time, and the progression of modeling environments has made many obsolete. As CAD has evolved into building information modeling (BIM) in the architecture profession, it is useful to consider the advantages of solar envelope generation within a BIM program. A plug-in to revit architecture (written in c# for the revit api) was developed to generate solar envelopes; the integration with BIM facilitates the analysis and use of solar envelopes in design.