Volume 26, Issue 2 - March/April 2012


Energy Matters
Glass Plays Key Role in New Green Code Developments
by Dr. Thomas Culp

With base energy codes continuing to advance, new green construction codes will also have an increased influence over commercial architecture, with glazing playing a very important role. The 2012 International Green Construction Code (IgCC) will be published this spring. ASHRAE 189.1 for high- performance green buildings was first published in early 2010, and a new edition was just released this past January. These standards cover many of the same concepts of Leadership in Energy and Environmental Design (LEED) such as site selection, material use, energy efficiency and indoor environmental quality, but they are written in code format instead of as a point system. While it is still uncertain how widely these new codes will be used, they are likely to first be used in publicly funded projects.

“The IgCC requires 50 percent of the net floor area for one- and two-story buildings to be in day-lit zones, and 25 percent of the net floor area for taller buildings.”

The Breakdown
Commercial glazing and framing is a key component in many aspects of the IgCC and ASHRAE 189.1. Here is a look at some things to expect from these codes:

• These standards include the next step in energy efficiency over the base codes, taking an initial step along the path toward zero-energy buildings. The glazing industry is already offering advanced products to meet this challenge, including double glazing with two low-E coatings (#2 and #4 surfaces), triple glazing and advanced framing with wider or double thermal barriers.

• Daylighting plays a critical role. The IgCC requires 50 percent of the net floor area for one- and two-story buildings to be in day-lit zones, and 25 percent of the net floor area for taller buildings. In addition, there are requirements for a minimum amount of sidelighting and toplighting area, either in the form of minimum effective aperture or minimum illumination in a daylighting analysis. There are analogous requirements in ASHRAE 189.1. This will require well thought-out daylighting design, including strategic placement of glazing and skylights and consideration of glare control.

• In the prescriptive path, both standards have requirements for either external shading (e.g. aluminum sun shades) or automated dynamic glazing.

• There are strong requirements for providing on-site renewable energy, most likely solar photovoltaics. These can be traditional rooftop PV, but also can be building integrated photovoltaics (BIPV) incorporated into spandrel area, atriums, or even vision glazing.

• The material selection requirements will continue to promote sustainable materials, such as aluminum curtainwall and window framing, which contributes through recycled content, recyclability, and a positive life cycle analysis.

Dr. Thomas Culp of Birch Point Consulting in La Crosse, Wis., serves as code consultant for the Glass Association of North America and is engaged in the energy code process.

Architects' Guide to Glass & Metal
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