A number of people have recently requested information on how to complete an overshadowing exercise I set some Masters students at a couple of different Universities. As a result, I have added some more descriptive text and reformatted the original answer sheet to describe both the exercise problem and an example method that can be used to generate the answer.

With an increasing regulatory emphasis on energy efficiency and building performance analysis within the design process, the need for a smooth and hassle-free conversion from CAD tool to analysis engine is becoming critical. This article considers the issues associated with such a transition, looking in detail at the kind of information required by different performance analysis / simulation tools and what is actually available in a typical CAD drawing. It looks at the various options available, including the growing influence of Industry Foundation Classes (IFCs) and gbXML, and what their impacts might be.

In many building regulations and simplified analysis methods, solar effects on buildings are characterised only by the exposed apperture area and the average solar transmittance of the glazing used. However, the true impact of solar radiation on the internal conditions within a space are often much more complex than this simple relationship would suggest. To explain the problem, this article tracks solar radiation as it enters through a window and looks at the various factors that govern its resultant effects.