White Papers

2 Copyright ©2013 Sefaira Ltd. F O U R RU L E S O F TH U M B TH AT CO U L D L E A D YO U A S TR AY Introduction For many decades, rules of thumb have been the go-to resource for architects seeking to design high-performance buildings. Rules of thumb provide a convenient shorthand for capturing general responses to climatic conditions, and for illustrating the fundamentals of how energy is captured, lost, and used in a building. However, rules of thumb have their limitations. They generally do not take into account the specifics of a project's site, context, usage, or building shape. They do not apply well to "edge cases" that fall outside the bounds of normal expectations — but neither do they help designers identify which designs are edge cases and which are not. Furthermore, they do not identify which design elements have the biggest impact on performance. As a result, rules of thumb end up being prescriptive rather than flexible — dictating design rather than empowering architects to understand tradeoffs and meet performance goals creatively. This paper explores four common rules of thumb related to the building envelope, including: building orientation shading depth glazing ratios operable area for natural ventilation. In each case, normal variations in site, usage, and building design can cause the rules to lead to less-than-optimal designs. At times they point in the wrong direction entirely. Today, designers have a number of alternatives to using rules of thumb. Fast, intuitive sustainability analysis can provide real data to drive design decisions in the right direction from a project's inception.

• Cover