WDMA Technical Conference tackles daylighting, codes and emerging technologies

The break-out sessions during the Window and Door Manufacturers Association Technical Conference included a mix of both policy and technical meetings, focused on the industry's push for increasingly higher performing products. The conference was held June 26-28 in Bloomington, Minn.

Stephen Selkowitz presented a break-out session titled "Windows for the Next 30 Years." Buildings consume 40 percent of total U.S. energy, presenting a major opportunity for the building industry, said Selkowitz, who is department head, building technologies department, Lawrence Berkeley National Laboratory.

Changes coming to the industry will include 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 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, not prescriptive, codes.

Retrofit is becoming more important, he added. "The [Department of Energy]'s vision several years ago was net zero building. Today, the DOE vision is retrofit," Selkowitz said.

Looking at window products, Selkowitz predicts net zero windows and dynamic solar control. "The 2030 future typical window will be zero net energy use," he said. "Additionally, we'll see low-E everywhere, and new technology options such as dynamic, triples and vacuum glazing breaking through."

In a related break-out session, Helen Sanders, vice president, technical development, Sage Electrochromics, discussed the importance of promoting the benefits of daylighting, particularly as the industry fights efforts to lower the window-to-wall ratio in the prescriptive path for ASHRAE 90.1. While the glass industry held off the push to lower window-to-wall ratio from 40 percent to 30 percent in the 2010 ASHRAE, 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. However, the most efficient building is one that "harvests natural daylight and uses it to offset electric lighting," she said.

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.

However, 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. "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."

Another break-out session included a technical discussion of No. 4 surface low-emissivity coatings from two perspectives, by Tracy Rogers, director, industry relationships and advanced technology for Quanex Building Products, and Jim Larsen, director, technology marketing, Cardinal Glass Industries.

Rogers presented on 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 [low-E] 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 4th surface low-E, including more stringent criteria for Energy Star and the International Energy Code. "4th surface low-E enhances double pane IGs, matching performance of a skinny triple pane unit," he said. "The question is, is [4th 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 4th 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 4th surface low-E. "It is a trade off, but you have to ask whether this is a level of field complaint?" Larsen said.

Additional break-out sessions during the conference included a Canadian Code Update by Jeff Baker, technical director of WestLab; "Practical Experience with, and Advances in, the Use of Thermally-Treated Wood in Europe," by Claus Staalner, C.S. Industries LLC; "The Environmental Impact of Building Materials: The Growing Push for Impact Assessments and Declarations," by Jeff Inks, vice president, code and regulatory affairs, WDMA; "A New Tool for the Trade: Efficient Windows Collaborative, Revised," by Kerry Haglund, senior research fellow, Center for Sustainable Building Research, University of Minnesota; and an architectural door technology update, by Jeff Lowinski, vice president, technical services, WDMA.