The Road to R5 and Beyond
by Tara Taffera
“It’s time to move beyond double-pane. We need to support
highly insulating windows beyond the tax credits.”
So said Marc LaFrance from the Department of Energy (DOE) during the summer
meeting of the American Architectural Manufacturers Association (AAMA).
LaFrance’s comments aren’t new. We’ve heard statements such as this for
a while now as the DOE begins to tackle phase 2 of the latest revisions
to the Energy Star® criteria for doors, windows and skylights. (The
DOE’s Richard Karney, program manager for the Energy Star windows program,
has said research on phase 2 begins this fall). As the industry moves
toward phase 2, talk always turns to triple-glazed units—and particularly
that windows may be hard-pressed to meet the new requirements without
But if the phase two numbers end up moving manufacturers toward triple-glazed
units, are the door and window manufacturers ready to produce these units
in a large quantity? And are consumers ready to pay for them? The answer
seems to be a simple no.
In fact, LaFrance said that he disagrees with Karney concerning phase
2 of the revisions.
“I personally think we should hold off on phase 2,” he said. He said doing
so would allow the “triple-pane market to mature.”
LaFrance did point out, however, that for the near term, the DOE’s goal
is an affordable R5 window in the marketplace. That’s the other problem
with an R5 window: currently it can’t be produced at an affordable price.
Getting to R5
So the DOE is working with the industry to change that. The agency recently
announced that its National Energy Technology Laboratory, on behalf of
the Office of Energy Efficiency and Renewable Energy’s Building Technologies
Program, has awarded GED Integrated Solutions Inc. a Production Engineering
and Commercialization of Residential R-5 Highly Insulating Windows research
and development grant. The grant will assist in the company’s effort to
design and develop a high-volume, low material and labor cost automated
manufacturing system that results in a high-performance R-5 value window
system, and will enhance the industry’s ability to provide homeowners
with affordable, highly-efficient residential windows at minimal cost.
Tim McGlinchy, executive vice president of engineering, NxWare and customer
service for GED Integrated Solutions, says the research is currently in
the validation/investigative stage and that is set to be complete in the
third quarter of this year. Once that initial phase is complete, McGlinchy
says the remainder of the project will take about 15 months.
“We are working with our customers to develop a feasible, high-production,
low-cost R-5 window design that can effectively be implemented into manufacturing
and commercialization,” says McGlinchy. “We are validating that our performance
and cost approach works in both vinyl and wood windows.”
But, more importantly, GED has to fulfill the DOE’s goal concerning cost
of the final product. That goal is to get the cost of an R5 window to
be only $4 a square foot more than a current Energy Star window.
So for an average 12-square-foot Energy Star window that would cost $200,
the goal would be for the R5 model to sell for $250.
“For current window designs today, with performance levels approaching
R4 or higher, triple IGU construction versus a dual IG unit configuration
is most likely going to be required,” says McGlinchy.
Representatives of some of the major glass manufacturers with whom we
spoke agree with him.
“We’ve reached the U-value limit of low-E coatings,” says Mike Rupert,
director of technical services for PPG Industries. “The next alternative
is to employ triples.”
Andy Russo, market development manager for Guardian Industries, also says
that a glazing change will be needed.
“Particularly in zones 4 and 5 it will be difficult for manufacturers
to meet the new requirements without some sort of glazing change, whether
it’s through triples or vacuum insulating glass (VIG),” he says. “This
is presuming that the proposed 2013 Energy Star changes hold true.”
But again, it comes down to cost.
“Right now it’s a choice as it [an R5 window] comes at a high price tag
and we’re trying to remove that choice for the consumer,” says McGlinchy.
He adds that the end goal is for consumers to save more energy, knowing
that they won’t make a purchase if it’s not cost-effective. For a product
to be cost effective for the consumer it has to be for the manufacturer
as well, and currently it is not.
“We have to focus on high-speed automation,” says McGlinchy. “People can
make them now and some are on the market but it requires a lot of manual
labor. Maybe they make 50 to 100 per day. We want to turn that into higher
He adds that some manufacturers claim to have window ratings as high as
“You can make about anything if you have an unlimited budget,” says McGlinchy.
“What I’d like to know is the cost of that window.”
He also stresses that reliability comes into play and it is important
that the window lasts for 20 to 25 years.
McGlinchy stresses that the research being performed by GED will benefit
the industry as a whole.
“Our focus is bringing affordability and profitability to our customers,”
he says. “If they can’t afford it, then their customers can’t afford it
and that’s obviously not good business.”
Though the industry speculates that manufacturers may only be able to
meet the phase-two numbers through the use of triple glazing, it’s still
anyone’s guess as to how the numbers will play out.
“It’s hard to tell where the numbers will end up,” says Rupert. “We’ve
seen U-values in the low to mid .20s that will likely require the use
of triple glazing.”
He says this is less expensive than some other alternatives such as moving
“The cost of krypton is way too high,” says Rupert. “Manufacturers won’t
move toward krypton.”
Rupert believes the DOE’s goal of producing a cost-effective R5 window
can be done, but it will mean added costs for manufacturers that will
have to make changes to their processes.
“You don’t add different factors, such as a different size sash, etc.,
without added costs,” says Rupert. “But someday a triple unit will be
But there is still a long road ahead. Russo says the window industry is
in a situation similar to the car industry.
“The high-end public is used to driving large, CO2-emitting vehicles and
considers these luxurious,” says Russo. “Windows have followed a similar
trend. Beautiful, low-profile wood and aluminum-clad wood windows
define luxury in most high-end homes. These products are very elegant,
but many of them are the opposite of what you need in terms of thermal
insulation. So now some of these lower-performing windows will have to
meet new requirements that will present a challenge.”
He says in many of these cases, it will not be possible to drop in a triple-glazed
solution and achieve the proposed Energy Star performance. Significant
re-design of windows, frames and sashes likely will be required.
“If you don’t design it right, you don’t get to the right performance
solution,” says Russo. “The end result will be larger, bulkier frame designs
and thicker glazings—pretty much what you see in most of central and northern
Europe where more stringent energy codes have taken hold. This is
something to which the market and the window companies will have to adjust.”
Destination: Vacuum Glazing
Another option may be available to meet the higher numbers and that is
vacuum insulating glass (VIG). (For more on VIG see October
2008 DWM page 38, which can be accessed online at www.dwmmag.com.
Just click on the archives.)
“In the future we’re looking at an R10 window, maybe vacuum glazing as
well,” said LaFrance when speaking before AAMA attendees. “We will see
dynamic windows as a viable option in the years to come.”
“Many window companies are pursuing research into production of triple
glazing and VIG as a parallel effort,” says Russo. “The only difference
is that for triple glazing there are solutions on the market today … VIG
isn’t a solution to these issues today, it is a development effort.”
He adds that the modifications for triple glazing are fairly straightforward,
though they are costly to the manufacturer. He says VIG is more complicated.
“With VIGs you eliminate everything between the lites of glass and creates
a vacuum, which generates the highest possible insulating value,” says
Russo. “The bare essentials are the glass and the vacuum; because there
is a vacuum you need something to keep the glass from collapsing on itself,
so a matrix of tiny columns is used to hold the glass together at the
There are also technical issues that have prevented the product from coming
to market. These include the ability of the glass to maintain a vacuum
over time and the structural and thermal performance of the window in
total. Russo explains, “You can create the IG assembly to perform a certain
way, but when you put it into the frame or structure in the wall it might
act a different way.”
He says some benefits of VIG, in addition to its superior insulating properties,
is that these can be produced by using a much thinner profile.
Whether the upcoming higher R-values are met through triple glazing or
VIG, Russo says all products come up with a bit of a compromise.
Guardian has been researching VIG for several years, then shelved it for
awhile as “the low cost of energy did not drive the industry to be interested
in anything more than double-glazed solutions.”
“We produced a window that could achieve an R12 center of glass value.
Then the industry said, ‘Why do we need this?’” says Russo. “Two
years ago when the cost of energy went through the roof, we began researching
this again and working toward commercialization.”
Russo says that’s when interest for VIG began to peak.
But as is the case with triples, manufacturers need to be able to produce
them in volume and cost effectively and the industry isn’t there yet.
“To be successful and achieve the lowest cost possible, VIG needs to be
produced in a high-volume format. We’re looking at a very high degree
of equipment automation,” says Russo.
Production-representative VIGs (the glass portion) are expected to be
available in early 2010 and complete window solutions will follow as Guardian’s
window manufacturer partners launch their products.
And while Guardian may be close, it’s not the only manufacturer looking
“We’ve been looking into this for decades,” says Rupert. “We can achieve
an R10 window no doubt. But there are cost considerations with this technology
as well as technical issues that still have to be worked out involving
flexibility, use on various glass surfaces, issues surrounding its use
with tempered glass, etc.”
But industry experts agree that the technology can be a great way to get
toward highly efficient window products.
“When successful, VIG is a very good insulator,” says Rupert. “VIG will
play a role in the future.”
Tara Taffera is the editor/publisher of DWM magazine.
© Copyright 2009 Key Communications Inc. All rights reserved.
No reproduction of any type without expressed written permission.