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Cool Window and Glazing Products from the AIA Convention

Manufacturers showed off some highly innovative products at the recent convention in Washington, DC

Posted on May 24 2012 by Alex Wilson

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 glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill.-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(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. (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 daylightingUse of sunlight for daytime lighting needs. Daylighting strategies include solar orientation of windows as well as the use of skylights, clerestory windows, solar tubes, reflective surfaces, and interior glazing to allow light to move through a structure. 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-factorMeasure of the heat conducted through a given product or material—the number of British thermal units (Btus) of heat that move through a square foot of the material in one hour for every 1 degree Fahrenheit difference in temperature across the material (Btu/ft2°F hr). U-factor is the inverse of R-value. (assuming argonInert (chemically stable) gas, which, because of its low thermal conductivity, is often used as gas fill between the panes of energy-efficient windows. gas-fill) is a respectable 0.28 and the solar heat gain coefficient(SHGC) The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. 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 coatingVery thin metallic coating on glass or plastic window glazing that reduces heat loss through the window; the coating emits less radiant energy (heat radiation), which makes it, in effect, reflective to that heat; boosts a window’s R-value and reduces its U-factor. 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 (SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.) of 0.47 in the untinted state to 2% / 0.09 in the fully tinted state. When used with low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor. 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 vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). (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

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 its 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 home builders and homeowners. It won’t match the high-end European Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. 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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  1. Alex Wilson

May 26, 2012 9:13 PM ET

by Dan Kolbert

Alex - did you see anything about Pella's triple glazed product?

May 26, 2012 9:47 PM ET

Pella's triple-glazed windows
by Alex Wilson

I didn't make it to Pella's main booth at the AIA show. They have had their Energy Panel windows, which I've long liked, but I think I heard that they are coming out with a true triple-glazed window--as is Andersen (finally!).

I did stop by EFCO's booth, though. EFCO is Pella's commercial curtainwall company, and they have significantly improved the thermal breaks in their aluminum-framed curtainwall and window systems, and they can provide triple-glazed units. Here's a link to their website:

May 30, 2012 2:14 PM ET

Edited May 30, 2012 3:53 PM ET.

Intus is a game changer!
by Jason Peacock

Alex, Great article. I can't wait till more building products are integrated with solar PV. It just makes sense. I'm sure we'll see an evolution of building materials within the next few decades that none of us would have dreamed of. It's an exciting time to be in the industry. The standard paradigms are shifting. If you haven't already, take a look at Intus Windows. They are hitting higher performance benchmarks that you've been waiting for from the larger manufacturers and they're doing it now. Their triple glazed prices are competitive with all major US manufactures double glazed options. It may be newsworthy even for an article. Now is a great time to build a home and Intus makes it financially possible to use triple glazing.

U-0.088 (center of glass). That's an R-11.36. I don't see Marvin approaching this anytime soon.
U-0.16 (frame).
U-0.12 (whole window).
SHGC of 0.62
DP rating 70
Air Leakage 0.01

Pricing is again equally amazing. It basically takes away the argument that triple glazing is too expensive.

Intus Window Info Page.pdf 286.19 KB

May 30, 2012 2:25 PM ET

Edited May 30, 2012 2:26 PM ET.

Response to Jason Peacock
by Martin Holladay

Do a search on "Intus" on the GBA site and you'll get links to 18 articles. I reviewed Intus windows in an article published 8 months ago: New Green Building Products.

The Intus windows that are most affordable are vinyl. For some buyers, that's a problem. Others don't mind.

May 30, 2012 2:52 PM ET

U-factors for Intus
by Alex Wilson

I think your quoted U-factors for frame and whole-window are off by a decimal point, aren't they? Shouldn't those numbers be 0.16 and 0.12, respectively?

May 30, 2012 4:07 PM ET

Intus UPVC is not your typical vinyl window
by Jason Peacock

Martin, Intus has wood frame windows wood or aluminum clad with very competitive pricing. The glass values all stay the same. Their UPVC option is the most popular. They also have a passive house certified thermally broken aluminum clad window that is beautiful.

The "U" in UPVC stands for Unplastisized. Plastics that are added in typical vinyl windows make the extrusion process easier. Plastics make the material less dimensionally stable and susceptible to cracking and warping. Plastics don't allow the material to be recycled. UPVC is very stable in extreme temperatures and can be upcycled indefinitely into further production. The frames are very rugged and also have steel reinforcement in the center of the extrusions. The company that makes the extrusions is the largest in the world, Schuco. They are in Germany and adhere to the European Union's strictest manufacturing standards for restriction of toxics. These frames will most likely outlast the wood that holds them in place.

Alex, thanks for the corrections.

May 30, 2012 4:21 PM ET

Response to Jason Peacock
by Martin Holladay

Unless Intus has switched suppliers, Schuco does not supply their vinyl lineals. According to Intus representative Aurimas Sabulis, the company uses vinyl lineals manufactured by Deceuninck Group, a Belgian company.

May 30, 2012 5:05 PM ET

The "U" in UPVC
by Alex Wilson

From the research I did, plasticizers are not used in any American vinyl window extrusions and never have been. I do not believe there is any difference between UPVC and the PVC used in American windows. I asked two contacts in the vinyl industry about this a few months ago, and both were quite adamant about that. Phthalate plasticizers are widely used in flexible vinyl, including vinyl flooring, wire sheathing, and shower curtains--where it can account for 40-50% of the total weight I think. Vinyl window extrusions and vinyl pipe do not require these plasticizers. This is an important issue, because phthalate plasticizers are endocrine disrupters, and we want to avoid them.

May 31, 2012 5:10 PM ET

by Jason Peacock

Yes, you're right Deceuninck Group makes the UPVC frame. It's Schuco that makes Intus aluminum frames. My mistake.

Alex, I'm curious if other manufacturers have other additives besides phthalates plasticizers. It is my understanding that the European Union has much stricter oversight on manufacturing and restriction of hazardous substances than the EPA here in the USA.

Nevertheless, Intus has remarkable performance at a great price. I re-read your article on different windows from a few months back and one thing I'd like to clarify is that Intus Premmier 78 is a wood frame, aluminum clad option closer to $60 / square foot. We've been surprised at the level of quality at this price.

Jun 1, 2012 2:45 AM ET

Edited Jun 1, 2012 2:47 AM ET.

Sun Gaurd
by Marc Mallary

Looks great for skylights but who will sacrifice their view?

Jun 1, 2012 4:42 AM ET

Response to Jason Peacock
by Martin Holladay

The Intus prices guidelines I included in my article came straight from Intus. Obviously, large windows (especially large fixed windows) cost less per square foot than small windows (especially small operable windows), so the price per square foot will vary.

Jun 1, 2012 9:30 AM ET

Window pricing
by Jason Peacock

We worked with Linwood windows for a bit and they told us $100 - $120 / sf. When we got a quote it came it at $450 / sf. Our lesson was that you can't always believe what a manufacturer tells you. The nice part with Intus is that their prices keep coming in lower than their general pricing information. There are still good surprises in this industry and Intus is changing the way I look at what you can buy with your $. In the past you'd spend at least twice as much for a window with these stats.

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