WDMA Conference Examines Future of Windows, Daylighting

By Katy Devlin, Glass Magazine
July 10, 2012
Meetings & Events

Bloomington, Minn.–The future of windows, maximizing daylight and surface 4 low-E coatings were featured topics at the Window and Door Manufacturers Association Technical Conference, held here June 26-28.

Buildings consume 40 percent of total U.S. energy consumption, presenting a major opportunity for the building industry, said Stephen Selkowitz, who heads up the building technologies department at Lawrence Berkeley National Laboratory in his presentation looking at windows in the next 30 years. One important change in buildings overall, he predicted was a shift from components to systems. "If you build everything up piecemeal, you don't get nearly the bang for the buck," he said.

Additionally, the industry will see continued updates to mandatory codes and standards, updates to voluntary programs, and performance disclosure requirements that will mandate labeling of energy use on whole buildings. "In every building in Europe, you have to label the energy use. This is happening now in California and New York," he said. Selkowtiz also sees a push to more performance-based codes versus prescriptive ones.

LBNL does research on behalf of the Department of Energy and from the government's persepective, Selkowitz reported that retrofit is becoming more important. "The DOE's vision several years ago was net zero building. Today, the DOE vision is retrofit."

Looking at product developments, Selkowitz predicted, "the 2030 future typical window will be zero net energy use. Additionally, we'll see low-E everywhere, and new technology options such as dynamic, triples and vacuum glazing breaking through."

Helen Sanders, vice president of technical development at Sage Electrochromics, offered a talk about the importance of promoting the benefits of daylighting.  While the glass industry held off the push to lower window-to-wall ratio from 40 percent to 30 percent in the 2010 ASHRAE 90.1 standard, she said, the debate is back for next version.

The challenge for the glass industry is "the conventional view that the most energy efficient building is one with no windows," Sanders said. She asserted, however, that the most efficient building is one that "harvests natural daylight and uses it to offset electric lighting."  Building owners can maximize the potential of natural daylighting with a combination of lighting controls with energy-efficient fenestration, light redirecting techniques (clerestory, light shelves, etc.), and a method for handling glare. "Lighting controls have a much larger effect on energy use than reducing window to wall ratio or glass choice," she said.

The most important element of daylighting that the glass industry needs to promote is the human impact factor, particularly as lighting load costs continue to reduce, she said. "We don't put windows in buildings for energy savings. We put them in buildings for people," Sanders said. "We all know this, but how do we quantify it? The industry needs to figure out this message."

No. 4 Surface Low-Es
Another discussion of note at the WDMA conference was a technical discussion of No. 4 surface low-E coatings from Tracy Rogers, director, industry relationships and advanced technology for Quanex Building Products, and Jim Larsen, director, technology marketing, Cardinal Glass Industries.

Rogers examined the potential for condensation in insulating glass units with fourth-surface low-E coatings. "You have a soft coat low-E on the No. 2 surface, and a hard coat on the No. 4 that reflects heat back, actually lowering the temperature of that interior lite of glass," he said. "That lite of glass is cooler than if it would have been clear.

"We want to take a look at effects of 4th surface low-E in terms of surface temperatures on that interior lite. [The industry] should be aware of some of these issues," Rogers said. "The problem here is that customers purchasing a high-quality window might then have moisture on the glass."

Larsen also responded to condensation concerns and discussed the motivations behind fourth surface low-E, including more stringent criteria for Energy Star and the International Energy Code. "Fourth surface low-E enhances double pane IGs, matching performance of a skinny triple pane unit," he said. "The question is, is [fourth surface low-E] going to cause catastrophic condensation problems in order to hit Energy Star numbers.

Both Rogers and Larsen offered condensation modeling data. According to Larsen's data, a unit with fourth surface low-E, argon fill and a warm-edge spacer could potentially see 300 hours of condensation in a year, up from 150 hours of condensation on a similar unit without the fourth surface low-E. "It is a trade off, but you have to ask whether this is a level of field complaint?" Larsen said.

The WDMA conference kicked off June 26 with presentations on building science and life cycle analysis. The event featured several WDMA committee meetings, as well as an update on Canadian codes from Jeff Baker of WestLab; a presentation on changes at the Efficient Windows Collaborative from Kerry Haglund of the Center for Sustainable Building Research at the University of Minnesota; and an architectural door technology update from WDMA's Jeff Lowinski.

The meeting, which also offered attendees tours of nearby Cardinal Glass Industries and Sage Electrochromics plants, was followed by a Windows Roadmapping Workshop, hosted by DOE, offering an update on its research and development activities.