Moving from Double to Triple or Possibly a New Technology

John G. Swanson
August 15, 2008
COLUMN : Opening Remarks | Energy Efficiency, Methods & Techniques

Questions and concerns about a possible shift to triple-glazing have been floating around the industry ever since the Department of Energy issued its preliminary announcement about potential changes to the Energy Star Windows program. The new, more stringent U-factors DOE said it was considering for Northern climates in a couple years would be tough to meet with even the best double-glazed, gas-filled low-E coated glass package. To meet the new numbers, companies would have to go to triple-glazing, or perhaps some new technology.
In June, DOE’s Marc LaFrance, speaking at the summer conference of the American Architectural Manufacturers Association, pointed to climate change concerns and our country’s growing need for energy independence, as well as the resulting building code changes and evolution of Energy Star. “All these things are moving forward together to move the industry from a double-paned package to pretty much a triple-paned package,” he said.
Following up on that general prediction, we used the poll in our WDweekly newsletter to see if and when the industry thought we’d be going from double to triple glass. Apparently, a good number of people out there think it will happen. We asked readers how long before triple-glazing will account for 25 percent of the market. In total, close to 40 percent predicted it would happen within the next 10 years. That’s not a very long time in our industry. Vinyl, and I would say low-E, were probably around longer than 10 years before they hit the 25 percent market share mark.
Another quarter of our respondents expect the shift will happen, but suggested it would take longer—perhaps 20 years. It’s interesting to note, however, that one quarter don’t think it will ever happen. Never is a long time. I suspect those responses are somewhat colored by the very legitimate cost versus value question that triple-lite presents the industry—and our customers—now. 
Going to triple-lite construction, most of us know, can add significantly to the cost of a product. It not only adds to the cost of the glass package itself, but the added weight might require a complete product re-design. Many manufacturers don’t see much of a payback in it—in terms of energy savings—for their customers either. 
DOE, by the way, sees new technologies as one way to make the payback equation work better. For one, it is supporting efforts to develop new triple-lite options—replacing the center piece of glass with some type of lightweight plastic. This would be similar to the Heat Mirror approach of making insulating glass, but would utilize some solid material in place of a film. Vacuum glazing is another alternative DOE cites.
Both these concepts are great, but the industry is skeptical they will be ready—particularly within the timeline proposed for more stringent Energy Star requirements. And even if these concepts evolve and become products that can be manufactured and shown to outperform current products, there’s another hitch. Will they come to market ready to go with a 20-plus year life expectancy?
Window & Door columnist Paul Gary, a Portland, Ore.-based attorney that represents window and door manufacturers, suggests the industry needs to lobby for some protection on this front. If cutting down on energy usage is a national priority—whether it’s because of climate change concerns or because we want to be more energy-independent—window and door manufacturers working to meet that goal should get some type of indemnification from legal action down the road. He states his case on page 54. but let’s look at a scenario: A new technology is developed. Window and door manufacturers adopt it to meet new codes and/or Energy Star criteria. Companies make real products in real plants, test them in a way that simulates 20 years of use and everything seems great. Then 10 years from now, we start seeing a deterioration in U-factors. Instead of the .20 originally simulated and tested, the number has crept up to a .24. Next thing you know, some law firm starts signing up homeowners for a class action suit...and so on and so on.
Okay, I may have gotten off track on the triple glazing discussion, but based on some of the pained and puzzled expressions I’ve seen among window manufacturers over the past six months, I think this is an idea worth floating.
And finally, I want to point out there is some definite enthusiasm for triple-pane among some manufacturers. “The simple fact is a triple pane sealed unit not only provides greater thermal resistance but increases the UV block and keeps the interior quieter as well,” one manufacturer wrote me.  “UV degradation may not lead to the replacing of the window unit but will eventually shorten the lifespan of the interior furnishings and finishes. This requires either replacement or refinishing of the materials and in the big picture the current mindset of the consumers is to have a sustainable home that reduces such costs.  As a manufacturer, consumer and a resident of this planet my hope is that (triple-pane) becomes a mandatory requirement for Energy Star.”