BETEC Attendees Learn Windows Don't Have to be "Energy Losers"
December 10, 2009

"The objective is to take windows from energy losers to neutral and then net-energy suppliers," commented Joseph Deringer, AIA, LEED AP, with the Institute for the Sustainable Performance of Buildings, during today's Building Enclosure Technology and Environment Council (BETEC) Symposium.

BETEC, which took place at the Washington Convention Center in Washington, D.C., in conjunction with Ecobuild America, taking place this week, focused on the topic of "Retrofitting Building Enclosures for Energy Efficiency and Sustainability."

Deringer filled in for the Department of Energy's (DOE) Marc LaFrance today on a presentation on window and building enclosure research at the DOE. Deringer began by stating that the DOE's (conservative) goal for energy efficiency is reaching net-zero-energy homes by 2025. Toward that end, he listed several core areas of DOE's goals for window research and development:

  • Commercializing cost-effective R-5 windows;
  • Development of affordable dynamic windows;
  • After developing R5 windows, working toward the next generation of R10 windows;
  • Promoting efficient products with enabling research;
  • Developing integrated daylighting strategies; and
  • Developing fenestration test and rating standards internationally.

Dudley McFarquhar of McFarquhar Group looked at some of the challenges of executing an energy retrofit for existing buildings in his presentation titled "Designing Commercial Energy Retrofits for Curtainwalls." Although McFarquhar early on defined a curtainwall as being able to be composed of various substrates, he also put the responsibility of energy efficiency on a building envelope's glazing materials. "If we talk about energy and the building envelope we're actually looking at the need to control light transmittance in the vision areas," he said.

Some of the things to keep in mind in planning an energy retrofit, he noted, include maintaining insulation at spandrel areas, focusing on air and water infiltration and reviewing the status of building materials such as gaskets, glazing, framing, sealants and, importantly, framing anchors. He also advised his audience of building engineers to determine what type of system is in place--whether stick-built curtainwall, unitized, etc.--as that will, to some degree, determine the retrofit design approach. He noted the age of a building can offer some information on the type of materials and systems you're likely to find yourself dealing with. For example, he noted, "The sequence of [unitized] framing is difficult for retrofit because you're stacking from the bottom up, etc."

Brandon Tinianov, chief technology officer of Serious Materials, focused specifically on "Advanced Glazing and Window Technologies."

"In my simple view of the world there's three generations of windows: high thermal insulation, dynamic glazings and building integrated photovoltaics (BIPV)."

He offered a timeline for when these technologies might be expected to become "mainstream" within the marketplace. "We're seeing high thermal insulation; dynamic glazings might come out in the next five years or so (not counting some of the commercial offerings available today) and I think in the next ten years or so we'll see BIPV."

The wait for BIPV is a result of high price tags and inefficient designs, Tinianov said. "It's interesting, it's novel, it's exciting, but it's just not compelling right now. These costs have to come way, way down."

Dynamic glazing, too, largely suffers from high costs that are keeping it from becoming commonplace in the market. He pointed to one problem of some systems. "The last problem with dynamic glazing is … what it does is it [the opaque portion] creeps across the window and becomes somewhat of an inkblot test … Some visual elements may be unappealing to the users."

Tinianov largely focused on more efficient developments for insulating glass units (IGUs). He began by noting that dual-glazed systems were invented as early as 1865. "What's really shocking is that if you dig into this patent you can actually see a triple-glazed unit," he said before providing his audience with background information on what's only now growing as an energy-efficient option for glazing.

"One of the reasons I'm very fond of multiple lite systems," Tinianov said, "is because you have so many possibilities." For example, he said, "In a system that just has three total lites I've got six available surfaces to work with … I've already got the benefit of a deeper thermal pocket, now I can start to tune that low-E coating."

Tinianov also noted, "Multiple lites are finding their ways into all kinds of iconic retrofits and I think that's very important." He pointed to the Sears Tower (CLICK HERE for related article) and Empire State Building (CLICK HERE for related article) as two notable examples taking up this trend.

Working on an energy-efficient retrofit? Let™ know. Email with your project information.

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