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I was at Efficiency Vermont's Better Buildings Conference in Burlington, Vermont last week. It's a great conference each February to learn about energy-efficient construction and find out about innovations in energy-conserving products, from lighting to heating systems.

Wandering around the trade show at Better Buildings, my attention was caught by several cut-away window corners at the Marvin Windows & Doors booth. For years at conferences, I've made it a point to ask the mainstream window manufacturers when they will give more attention to triple-glazed windows. Usually I just get blank stares from the salespeople. Marvin has offered a one-inch-thick triple-glazed window since the early 1990s, though never widely promoted the product. Then last year the company introduced a 1-1/2-inch triple-glazed window. Either can be ordered with whatever type of glass, low-e coatings, and gas-fill you want.

These triple-glazed windows are available with NFRC-certified unit U-factors as low as 0.21 (R-4.8), with solar heat gain coefficient (SHGC) options from 0.20 to 0.39, depending on the coatings and gas-fill specified. While all of these performance numbers have been third-party certified, other glazing configurations have not gone through that process yet. Significantly higher SHGC values are available by using a higher-solar-transmission glazing, such as LoE-179, and lower U-factors may be achievable, for example with two LoE3-366 coatings. Marvin uses glazing from Cardinal Glass Industries and can provide the following low-e options: LoE-179, LoE2-240, LoE2-272, LoE3-366.

Marvin can also put the coatings on different surfaces to optimize performance for different climates. This means that glazings that will work well for south-facing windows (high-SHGC) are available as well as low-SHGC glazings optimized for east and west-facing windows and for southern climates where reducing solar gain is a priority.

With the 1-1/2" glazing option, I was particularly impressed with the thermal breaks that are designed into the frame, which are especially important with aluminum-clad windows. It is an extremely well-thought-out window that carries Marvin's 20-year, fully transferable warranty.

Triple glazing is available in the following Marvin product lines: Ultimate Double Hung, Ultimate Double Hung Magnum, Ultimate Casement/Awning, Direct Glazed Polygon, Tilt-Turn, and 2-1/4" French Door. Triple glazing is not currently available on either of Marvin's fiberglass lines: Integrity and Infinity.

There is significant added cost for triple glazing, though these windows generally price out lower than most Canadian fiberglass-framed triple-glazed windows, according to John Beeman, of A.W. Hastings, a regional Marvin Window distributor. Once a decision has been made to go to triple glazing, the added cost of a second low-e coating is usually only a few dollars per square foot. Contact a Marvin dealer for pricing information.

The other significant development from Marvin is the availability, starting February 1, 2010, of chain-of-custody Forest Stewardship Council (FSC) certified for any wood species used in Marvin windows. Along with Marvin's softwoods are FSC-certified tropical hardwoods Cedro Macho and Mahogany and domestic hardwoods in the company's Signature products.

As with triple glazing, there is an upcharge for FSC-certified wood. Chain-of-custody Sustainable Forestry Initiative (SFI) certification is also available.

For more information:

Marvin Windows & Doors
Warroad, Minnesota

I invite you to share comments on this blog. Do you use or specify triple-glazed windows regularly? Any experience with Marvin's offerings?

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1 how much do these kinds of wi posted by mandeep on 02/22/2010 at 07:01 am

how much do these kinds of windows cost? I would like to round up an estimation, based on how much it would cost for a school to switch to these windows.

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