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I just spent three days at the American Institute of Architects annual convention in Washington, DC, including a fair amount of time at the massive trade show there. I didn’t make it all the way through the acres of exhibits over the eight hours or so I walked the floor, but I saw some really interesting products. I’m highlighting here a few of the windows and glazing-related products I found.
SunGuard PVGU from Pythagoras Solar and Guardian Industries
Guardian Industries, one of the world’s largest glass manufacturers, showed off two new products at the show. One of these was a unique building-integrated photovoltaic (BIPV) glazing system developed by Pythagoras Solar and marketed by Guardian. Most BIPV Glazing systems have thin-film or crystalline PV cells integrated into the glass directly, so the visible transmittance and daylighting potential are significantly compromised. Pythagoras has developed a unique solution to this problem: an insulating glass unit (IGU) with integral bars of tiny PV cells that intercept most of the solar energy striking the outside of the glass.
When you look out through Pythagoras glazing, the view is distorted, but some visibility is maintained and a remarkably high 49% visible transmittance is still achieved—so daylighting performance is still very good. When viewed from the exterior (see photo), you mostly see the PV cells due to the way light is refracted by the glazing.
The Pythagoras BIPV glazing produces up to 11.15 watts per square foot, which the company claims is up to three times the power density of most other BIPV glazings. The overall module efficiency is up to 12%, while the U-factor (assuming argon gas-fill) is a respectable 0.28 and the solar heat gain coefficient is 0.14—helping to control overheating. For more on this, visit Pythagoras Solar and Guardian’s SunGuard PVUG.
SunGuard EC dynamic glazing from Soladigm and Guardian Industries
Also on display in the Guardian Industries booth was a new dynamic glazing product: Soladigm glass. A few weeks ago I wrote about dynamic glazing, which can be tinted on demand to control glare and solar heat gain, and specifically SageGlass, the first company out of the gate with such a product that is commercially viable. Soladigm glazing, branded as SunGuard EC by Guardian, is made in Mississippi. Like SageGlass, it is an electrochromic glazing that uses electric current to tint the glass.
Soladigm’s coating is added to the #2 surface (the inner surface of the outer pane of glass in an IGU), and it can be used with clear glass or combined with a low-e coating on the #3 surface (the outer surface of the inner pane of glass). When used with clear glass, the tinting ranges from a visible transmittance of 62% and a solar heat gain coefficient (SHGC) of 0.47 in the untinted state to 2%/0.09 in the fully tinted state. When used with low-e glass, it provides 48% visible transmittance and 0.29 SHGC untinted and 2%/0.07 fully tinted. It is also available with four intermediate levels of tinting. The U-factor for these IGUs (assuming argon gas-fill) is 0.29 with clear glass and 0.24 for low-e glass and is the same whether tinted or not.
Like SageGlass, Soladigm’s coating consumes a small amount of electricity to achieve the tinting (0.1 watt per square foot) and about a third as much electricity (0.03 W/ft2) to maintain the tinted state. When the electric current is shut off, the glazing reverts to the clear state. For more information, visit Soladigm or Guardian.
Graham Fiberglass Windows
I have just completed work on a new BuildingGreen report on windows, for which we did extensive research on the window industry, so I was surprised to come across a product (and frame material) that I had never heard of. Graham makes a high-performance window, primarily for commercial-building applications, that is available triple-glazed with U-factors as low as 0.15.
What is unique about Graham windows is the frame material: a fiberglass composite that is 80% glass fibers and 20% polyurethane resin. Fiberglass is a highly durable and strong window frame material that is much more thermally stable than vinyl (PVC), but all other fiberglass windows I am familiar with are made with a polyester, rather than polyurethane, resin. According to Graham, with polyurethane you can have a higher percentage of glass fiber, achieving better strength properties. (I learned later at the show that it is harder to bond coatings to polyurethane resins than to polyester resins, which may explain the predominance of polyester-based fiberglass composites.)
Graham windows, including the fiberglass frames, are manufactured in York, Pennsylvania. They are typically fitted with Cardinal glass, which is available with various types of low-e, including Cardinal’s new LoE-i89 coating for the #4 surface (facing the room) of an IGU. For more information, visit www.grahamwindows.com.
Marvin Integrity Windows with triple glazing
For years I keep asking the largest window manufacturers when they will be introducing higher-performance products. Finally my wishes came true with Marvin’s fiberglass Integrity line. I learned at the Marvin booth that the company will be rolling out a triple-pane version of it’s popular Integrity line around the end of the second quarter of this year, though one of the Marvin reps in the booth allowed as to how that target date might slip.
There is nothing yet on the Marvin website about this window so I haven’t been able to examine performance specifications, but I think it will be a good choice for budget-conscious homebuilders and homeowners. It won’t match the high-end European Passive House windows in performance, but it will still be pretty good. Like most other fiberglass windows, the Integrity line is a fiberglass-polyester composite. A nice feature of the Integrity line is that only the exterior is fiberglass; the interior is wood, providing a nicer, warmer feel.
Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. He also coauthored BuildingGreen’s special report on windows that just came out. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.
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