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Proceedings of SimBuild Conference 2012: 5th conference of IBPSA USA

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Environment Mapping for Fast and Robust Calculation of Indirect Radiant Energy

Lars Schumann, Donald P. Greenberg
Program of Computer Graphics, Cornell University, Ithaca, New York, USA

Abstract: Inclusion of site data, such as the surrounding structures, terrain, and vegetation, all of which modulate the amount of indirect radiation exchange between a building and its environment is necessary for accurate building energy simulation. While the impact of indirect radiant energy is potentially large, it is also very time consuming to calculate. Thus building energy simulations tend to incorporate simplified environment models or to omit the indirect radiation calculation altogether. This paper describes how a computer graphics algorithm, environment mapping, can be used to accurately calculate the indirect reflected radiant energy from the environment. We encode the complete panoramic environment surrounding a surface as an image texture that serves as a look-up table parameterized by direction. Different pieces of information such as sky, clouds, and buildings or obstructions are stored in separate textures that can be quickly overlaid. The method is fast, accurate, robust, and scalable.
Pages: 263 - 269
Paper:
simbuild2012_04b_4_Schumann