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Webinar Teaches Architects About Benefits of High-Performance Fenestration

Post Time:Apr 17,2009Classify:Industry NewsView:252

A number of architects tuned in this afternoon to a webinar that offered insight into the role of glass and fenestration systems in creating energy-efficient buildings. The webinar on "Energy-Saving Architectural Solutions for High-Performance Buildings" was sponsored by the 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." Although this may be the case, 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" of energy use in U.S., explaining that buildings are the biggest user of energy in the country and growing the fastest, over transportation and industrial uses. "Over $400 billion each year" is spent on energy to cool, heat and light buildings, he commented.

Selkowitz also told his audience, made up primarily of architects, that one of the challenges in designing for high-performance fenestration is the image glass has as an energy waster. "There are conflicting views of the role of windows … in the '70s most windows were single-glazed and the conclusion was - well, the reality was that they were real energy hogs … If you turn the clock ahead now 30 years, what you often see in the magazines are highly glazed buildings … the reality is likely somewhere in between." The challenge, he noted is moving toward the more efficient image.

Selkowitz told his audience that there are essentially 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. As he reminded his listeners, "If you've just met the building you've designed the worst building you're legally allowed to."

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 a real opportunity, 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."

To explain why automation of systems can improve its performance Selkowitz pointed to a building in California that LBNL had measured for energy performance. A year after the first set of measurements, the building was retrofitted with daylight controls. "We learned we got greater savings in the North, which we didn't understand at first," he said. "People were using shades in the South and they don't often open the shades back up." Automatic shading would therefore help make use of daylighting benefits of glazing while keeping residents comfortable.

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 Selkowtiz described. 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, which he noted would be launched on April 27 and offer more points and credits. "Most noteworthy today is the doubling of points and credits for the energy and atmosphere category," he pointed out. He noted that credits there for "optimizing energy performance" have moved from 10 to 19, and added 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 on-site 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.

Source: USGlassAuthor: shangyi

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