Volume 23, Issue 3 - May/June 2009

New Product Focus

Webinar Teaches Architects About
Benefits of High-Performance Fenestration

A number of architects tuned in April 16 for a webinar that offered insight into the role of glass and fenestration systems in creating energy-efficient buildings. The webinar, titled “Energy-Saving Architectural Solutions for High-Performance Buildings,” was sponsored by Lawrence Berkeley National Laboratory (LBNL) and Alcoa.

Moderator Jackie O’Brien of Alcoa opened the session by commenting, “As many of you know, more than one-third of the energy consumed in the U.S. is consumed by commercial buildings.” And, O’Brien asserted, it’s a figure that will need to change. She pointed out that $50 billion in line items in the recent stimulus package referenced building construction or renovation, making knowledge of energy-efficient systems more important than ever.
Steve Selkowitz, program head of the Building Technologies Department of LBNL, also addressed the “big picture” view of energy use in the United States.

“Over $400 billion each year is spent on energy to cool, heat and light buildings,” he commented.

Selkowitz told his audience that there are three paths available when it comes to specifying the windows. The fist option is to “just meet the code” with small windows that offer nothing “special” in terms of shading or daylighting. “If you’ve just met the building [code] you’ve designed the worst building you’re legally allowed to,” he cautioned listeners.

The second option is to use conventional “good solutions,” such as modest-sized windows and skylights. Many of these options now utilize low-E coatings and double-glazing, as well as options such as manual interior shading, to maintain a comfortable interior environment.

The third, ideal, option is the new opportunity for “transparent intelligent façades.” Selkowitz explained that upon adding more glazing, a better set of tools is needed for optimization of the system, including automated shading and dimmable lights.

He also pointed to two challenges. The first is finding ways simply to become energy-efficient by minimizing winter heat loss and summer heat gains. The next step, which is growing imminently more probable, is utilizing the window in the creation of a zero-energy unit. These systems likely will need operable façade components and should rely on automation to best cooperate with HVAC systems and other utilities. Specifically, lowering lighting costs by utilizing daylight is the biggest opportunity for advancing the use of glass in energy-efficient buildings, Selkowitz said.

“This is the reason we often have windows in building. This is a great opportunity but a great challenge,” he added. “The façade system needs to be designed as part of an integrated system.”

During the second half of the webinar, Eddie Bugg, director of sustainable solutions of Alcoa’s Kawneer Co., focused on practical applications for achieving efficient buildings such as those described by Selkowtiz. But before running through some of the company’s available products, Bugg talked about the evolution of the LEED rating system from its previous inception as version 2.2 to the 2009 version.

“Most noteworthy today is the doubling of points and credits for the energy and atmosphere category,” he said, noting that credits for optimizing energy performance have increased from 10 to 19, and that there are a number of ways in which glass products can help achieve those credits.

Another change he pointed to is that the reference standard in LEED has been updated from ASHRAE 90.1 2004 to 2007, “which also raises the bar on being able to design buildings to energy code thresholds.”

In addition, credits for onsite renewable energy has increased from three to seven.

When it comes to choosing products to meet LEED credits and otherwise improve building efficiency, Bugg noted, “You can’t come up with just one [window] product to use universally on any project on your drawing boards today.”

But as this program stressed, windows shouldn’t be overlooked in the critical role they play in making buildings more efficient. AG

New Green Building Standard Could Help Encourage Low-E Glass in Residential Structures

The development of the 2008 National Green Building Standard (ICC-700) may help further promote the use of low-E glass. The International Code Council (ICC) says its standard is designed to provide guidance for safe and sustainable building practices in high-rise residential buildings as well as new and renovated single-family homes.

The standard’s rating system allows architects/designers, builders and communities to choose the levels of high-performance green buildings that best suit their needs. For example, one key provision of the standard is to offer energy performance starting at 15 percent above the baseline requirements of the 2006 International Energy Conservation Code (IECC).

“Whether they use the performance option or the prescriptive path, the standard will reward lower solar heat gain coefficients (SHGC) in the south, and lower U-values in the north,” says industry consultant Thomas D. Culp, Ph.D. “Both will promote low-E in all regions, and possibly some triple-glazing in the north. Credits are also available for sun-tempered design, passive cooling design and passive solar heating design. These options reward builders for good practices such as optimally orienting the building and glazing, using higher SHGC in the south, using larger overhangs or other methods of shading, placing operable windows for cross ventilation and using thermal mass. These can give three to 13 additional points in the energy efficiency category, on top of points related to the basic window and building energy performance.”

Architects' Guide to Glass & Metal
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