March 17, 2010

Window on the future


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Jack Milton/Staff Photographer: Rumen Shopov assembles a triple-glazed window at Paradigm Windows, portland, Thursday, April 17, 2008.

Jack Milton

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Jack Milton/Staff Photographer:Triple-glazed glass at Paradigm Windows, Portland, Thursday, April 17, 2008.

Jack Milton

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Staff Writer

Congress wants to raise the average fuel efficiency for cars and trucks to 35 miles per gallon by 2020. That's fine, but Sean Flanigan is more interested in windows that do better than 0.35 today.

Flanigan is research and development manager at Paradigm Window Solutions in Portland. The company has just begun selling a high-performance window that's twice as efficient as the government's minimum Energy Star rating for Maine's climate, which is 0.35 U-value.

Paradigm's new vinyl window is called the Hybrid. It has a U-value of 0.18, which refers to the rate of heat loss. To use the car analogy, this window gets twice the gasoline mileage.

As heating and cooling costs rise, contractors are stuffing more insulation into walls and ceilings. But windows, prized for admitting light and ventilation, remain a confounding, thermal hole in homes and offices. Even today's best windows allow a steady stream of energy dollars to float into space.

That's why companies such as Paradigm are racing to create a better window. The development of the Hybrid provides some insight into the progress made and challenges yet to be overcome.

The most basic window is a single sheet of glass. Fifty years ago, the best a homeowner could do was hang a storm window and create a crude air space. Window makers soon began sealing two panes of glass together to form a tighter, double-glazed window. By the 1980s, they were bonding special coatings inside the glass to reflect heat.

These were improvements. But the typical window sold in Maine today that meets the government's Energy Star standards -- double glazed with a heat-reflective coating -- still only has a fraction the insulating value of a modern wall.

''They've been out there 25 years,'' Flanigan said. ''There's been some evolution, but it hasn't been driven by Energy Star. The 0.35 standard is very easy to accomplish these days.''

No surprise, really. Until heating and cooling costs started to get really nutty, there wasn't much financial incentive for window makers to go beyond the standard. Contractors and customers wouldn't pay for it. Record oil prices changed that.

''Customers are becoming more knowledgeable,'' Flanigan said. ''It's a constant focus these days, how to save energy.''


Paradigm is a subsidiary of a 50-year-old, family-owned building products distributor, Applicators Sales & Service Inc. of Portland. Paradigm was spun off eight years ago to create a vinyl window targeting the energy concerns and architectural profiles of homes in the Northeast. The company declined to discuss its financial or employment figures, except to say it's growing.

The goal of creating a better window came in part from Flanigan's desire to meet a new performance benchmark being promoted by a green building trade journal. It features a U-value of 0.20.

Many people are familiar with R-value, a measurement of how well a material resists heat flow. Think of wall insulation, rated at a minimum of R-19 in Maine. With R-value, the higher the better. But U-value is the inverse, so Paradigm wants a window rated much lower than the 0.35 Energy Star minimum.

A computer glitch at the factory early this week was stalling production of the Hybrid, but the crew put together a sample window to show how it's done.

Paradigm buys glass already covered with a heat-reflective coating and cuts it to size. A technician surrounds the sheet with a high-tech plastic spacer, designed to slow heat flow around the window edge, and slides it across a work table to the next station.

There a worker sets in a center pane of clear glass. On top of that goes another pane of heat-reflective glass, creating a triple-decker sandwich of glass and air. The sandwich is slid into an oven, which seals and compresses the unit.

When the unit comes out of the oven, one corner of the window spacer is peeled back. A worker uses a hose to pump krypton gas into the two air spaces.

In basic windows, air currents inside the panes can transfer heat. Pumping a nontoxic, inert gas, such as argon or krypton, into the space slows conductive heat loss. Argon is common today in high-performance windows. Krypton, which is denser, works better. But it's very expensive; the small tank of compressed gas at Paradigm, topped with a padlock, costs $5,000.

For all the worrying over the pane, glass is only a piece of the window picture. Heat also escapes through the frame, and Paradigm takes an extra step to insulate the vinyl trim pieces. At another station, a worker uses a gun to shoot expanding polyurethane foam into the frame channels.

The final product costs roughly 20 percent more than a conventional window. But as energy prices rise, the extra expense is becoming worthwhile.


One of the first Maine contractors to install the Hybrid is Kasprzak Builders of Waterboro.

Kasprzak builds condominium communities in southern Maine. It chose the Hybrid as part of a new Energy Star construction package the company is promoting. The package is designed to cut a condo's average heating oil consumption from roughly 700 gallons a year to 500 gallons.

The company recently put the high-performance windows in four units in Gorham. The upgrade costs nearly $1,250 a unit, according to Stephen Kasprzak, the company's president. But with less heat escaping through the windows, the house will be more comfortable and affordable, Kasprzak said, which is a big selling point these days.

Paradigm may be the only production maker in Maine with such a frugal window, but some competitiors are using similar technologies.

Pennsylvania-based Gorell Windows & Doors is promoting the Ultra Master III, which features a similar triple-decker. In Ohio, Gilkey Window Co. couples the glazing technology with a multi-chamber honeycomb design in the vinyl frame to reach an 0.19 U-value.

Some companies make thicker windows for commercial buildings, which allows for more layers. Southwall Technologies and its Heat Mirror insulating glass sell a unit with a U-value of 0.08. Translated into the more-familiar R-value, that's 12.5 -- comparable to a wall with 3.5 inches of fiberglass insulation.

For window makers these days, the question is, how low can you go?

There's still room for improvement, according to James Benney, executive director of the National Fenestration Rating Council. The nonprofit council administers a certification and labeling program that helps consumers compare the energy performance of windows, doors and skylights.

Aside from tweaking available techniques, engineers are working with vacuum glazing, like in a Thermos bottle. Creating a vacuum to stop heat movement isn't a new idea, Benney said, but the challenge is designing supports to keep big sheets of glass from collapsing under pressure.

Window makers -- like auto manufacturers -- also are getting a nudge from the federal government. The Energy Star program is close to finalizing a plan to lower its U-value standards over the next seven years, among other things.

As U-value targets fall, Sean Flanigan is thinking about how to reach the next level. There's no room in the standard window sash for a fourth pane of glass. Maybe better coatings will emerge, he suggested, and less-conductive gases.

''We may be at the limits with current technology,'' he said. ''But we certainly expect the glass companies are working on that next generation.''

Staff Writer Tux Turkel can be contacted at 791-6462 or at:

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Additional Photos

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Jack Milton/Staff Photographer: Brian Lister injects polyurethane foam into a window frame at Paradigm Windows, portland, Thursday, April 17, 2008.

Jack Milton

click image to enlarge

Jack Milton/Staff Photographer: Krypton gas is used in triple-glazed windows at Paradigm Windows, portland, Thursday, April 17, 2008.

Jack Milton


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