Stirring the Pot

October 4th, 2022 by Nathan Hobbs

Manufacturers Explore New Recipes to Meet Energy Star Requirements

By Drew Vass

The race is on for door and window manufacturers, as they mix-and-match insulating glass (IG) technologies to meet impending Energy Star requirements. The U.S. Environmental Protection Agency (EPA) is expected to finalize Version 7.0 any day now, including steep changes for U-factor and solar heat gain coefficient (SHGC) ratings. To keep their products certified, manufacturers say they’ll do what they’ve always done: pursue better coatings and other improvements for double-pane glass. But experts warn that won’t be enough for some door and window products. That has even the longest-standing companies exploring other options. With about a year to go before Version 7.0 takes effect, Bill Sifflard, chief marketing officer for Quaker Windows and Doors, says his company assembled a review team to evaluate the impacts on current and future products. Meanwhile companies like Andersen Corp. “continue to evaluate the final draft specification,” says Brandon Berg, vice president of research, development and innovation.

Mixing Old and New

While manufacturers are expected to return to their usual bag of tricks—including additional low-E coatings, better thermal spacers and other upgrades— even in cases where those changes will meet the new requirements, there is no one-size-fits-all solution. Instead, each product requires its own formula, manufacturers tell [DWM], in some cases including more advanced forms of IG.

But the search for better performance is more than just a pain in the glass. Under the pressures of Energy Star, “I think now we’re into exciting times,” says Bill Davis, technical service and product manager for Vitro Architectural Glass. “We don’t see that as a bad thing. We’re positive about the changes they’re proposing with Energy Star 7.0. We think that the public will be pleased to benefit from the increased energy efficiency that goes along with these products.”

Traditionally, door and window companies have leaned on IG manufacturers to produce better versions of ¾-inch double-pane glass, which has helped them to avoid any major overhauls to door and window products over the years. But the ability of double-pane glass to raise the sum performance of finished products has narrowed to a degree that in some cases necessitates moving to triple-pane, vacuum insulating glass (VIG) or thin-triple IG. (For a look at how various glass upgrades impact performance, see the article on p12.)

With Draft 2 of Version 7.0, EPA officials backed off of the originally proposed U-factor requirement of 0.24 for the North-Central zone, acknowledging that those measurements would be “a tough U-factor to get to with two panes of glass.” By adjusting the U-factor requirement by a mere 0.01, they’re convinced that other technologies will enable double-pane products to meet the 0.25 mark, including surface-four low-E coatings. For example, Guardian’s ClimaGuard 70 will meet the U-factor requirements across most climate zones, says Suresh Devisetti, director of product management for Guardian Glass Americas, but, with the addition of a surface-four low-E coating, the product will meet the stringent North-Central requirements in a double-pane configuration. At the same time, the company is also working with its customers to develop entirely new products, Devisetti says.

“From my perspective, it looks like many of the zones and performance targets can still be achieved with [double-pane insulating glass] technology, but I think we’ll see more interest in surface-four low-E [coatings] as a result,” says Kyle Sword, Pilkington’s business development manager of Architectural Glass, North America. But surface-four coatings aren’t a magic bullet, Davis and others warn. “I think they’re at the level where a surface-four coating won’t [always] be enough,” he says. “You would also need help from other components. You would need a very high performing spacer. You would need a very high performing frame. Not just your standard frame would make it. Certain window types might not make it, like a double-hung type window, with a meeting rail, where there’s conductivity.” For this reason, “I think triple glazing is still going to be a requirement, to get many of these products to qualify,” Davis says.

With the addition of a surface-four low-E coating, double-pane IGUs are still a viable option for vinyl windows in the Northern and North-Central climate zones, Devisetti says, but it will also take the right gas filling and spacers, he adds.

In this way, “Version 7.0 will drive window makers to the best performing warm-edge spacers,” suggests Robert Struble, director of marketing for Vitro. “It will also narrow their low-E glass choices to the very best performing products.”

Seizing the Moment

Even when double-pane IG offers the most cost-effective solution, there are indications that some manufacturers are ready to move on to higher performing options.

“We’re seeing more interest in triple-pane glass and thin-triple technology,” Sword says. “Thinner, lighter-weight and higher-performing products have
always had a place in the market and, as regulations tighten, I think we’ll see more interest and demand.”

Case in point: NSG Pilkington has seen an uptick in the use of VIG and large-format thin-triple glass, Sword says.

There are also more reasons to avoid triple-pane glazing than just the dilemmas of weight and thickness, Sifflard points out. “If changes require the utilization of triple-pane IGUs, then as an industry we are going to see more price increases to meet Energy Star 7.0, not to mention the additional strain on glass suppliers to meet increased demand,” he says.

Instead, it’s more likely that manufacturers will use triple-pane where it’s deemed the best or only option, while turning to other products where it makes feasible sense. In this way, Davis says he feels that use of triple glazing could increase in non-operable products, which don’t have to contend with heavier sashes for operability.

“We work with customers to best fit their demand needs in terms of weight, thickness and performance, so it’s more design driven than product driven,” Sword says.

With such complicated decisions to carve out, the industry will also be forced to market and explain a wider range of options to consumers, which has some deploying new tools for specification. Guardian, for instance, plans to lean on a new online resource known as the Residential Glass Customizer, which breaks down various components and options. The same site can also serve as a tool for door and window manufacturers, to help position them “as experts while connecting with homeowners to help them understand glass performance,” Devisetti suggests.

As manufacturers shop their options, tools such as Guardian’s customizer also allow door and window manufacturers to explore the costs for various pathways to compliance for Energy Star 7.0. “We know there are concerns around cost effectiveness when adopting new standards, so we’re prepared to provide all necessary support to explore options via technical resources, including region-specific recommendations, energy modeling and specification reviews to help customize a solution,” Devisetti says.

Solid Competition

The push for Energy Star 7.0 brings door and window manufacturers closer to another evasive hurdle: solid wall performance. For decades now, “windows have been the poorest performing part of the wall,” Davis points out. “We can’t continue down that path, or folks in our industry are going to see window-to-wall ratios reduced.”

There are existing technologies, such as triple and quad-glazing, VIG and dynamic glazing, that are capable of matching the R-13 performance presented by today’s solid walls, Sword points out, but it will take more than that to help fenestration catch up, he adds.

“R-13 center of glass performance is possible now, but with current R-2 frames, the effective window R-value drops to R-6 or R-7,” Devisetti says. “Today, the return on investment can be challenging for an increase in R-value beyond an R-6 window.”

That has glass manufacturers dreaming up their next big steps.

“[VIG] can be made into a hybrid unit and that’s really the way to get there,” Davis says. “If you use a triple silver coating on an outward lite, and then have a gas space, air or argon … and then you use a VIG unit as your inboard lite of glass, with a triple silver outward coating … you can get to an R-20,” he says.

Of course, the cost for such recipes will have to decrease significantly if the industry is to ever cook up those options.

Drew Vass is the editor of [DWM] magazine.

To view the laid-in version of this article in our digital edition, CLICK HERE.

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