Case Study: Building Envelope Design Under the 2009 Codes - Glazing Ratio Requirements

This case study examines how the maximum allowable glazing ratio (also called fenestration area)—mandated by the latest energy codes—affects the design and construction of buildings. The scope of this paper is commercial buildings, which includes multi-unit residential buildings over three stories. The case study is based on an analysis undertaken during the design of a high-rise residential building in western Washington. Energy codes stipulate minimum requirements for energy-efficient design and construction of commercial and residential buildings. In the United States, there is no nationwide energy code. So code adoption and enforcement occur at the state and local level.

Some states have adopted ANSI/ASHRAE/IESNA Standard 90.1-2007, Energy Standard for Buildings except Low-Rise Residential Buildings (ASHRAE 90.1-2007). However, most states have adopted the 2009 International Energy Conservation Code (2009 IECC). And a few states—including California, Oregon, and Washington—have their own “home-grown” energy codes. Every three years, energy codes are revised to continuously improve the energy efficiency of new and renovated buildings. Consequently, stricter energy conservation measures are adopted with each code cycle. Since this paper’s case study building is in the state of Washington, the paper will also discuss some of the requirements of the 2009 Washington State Energy Code (2009 WSEC).

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