Finding the top Greenbuild products among 900 exhibitors is no easy task. This week we introduce you to our favorite windows from the show.

Greenbuild expo floors are typically chaotic and crowded and so vast that it is difficult to find the innovators among the throngs of people, glaring LED signage, and innumerable booths. This year's Greenbuild in Toronto had almost 900 exhibitors spread out over two expo floors separated by a significant walk, which made the search that much more challenging.

Fortunately, I enjoy a good challenge--and the exercise--and I was rewarded by finding some interesting products destined for GreenSpec. For this installment, let's take a look at some windows.

R-20 (!) quintuple-pane windows

As always, there were quite a few companies offering windows/glazing with impressive U-factors. Southwall's Heat Mirror film has been around for years, but the company is now offering a quintuple-glazed unit with a ridiculously low center-of-glass U-factor of 0.05 (or R-20, which is better than many walls!). This is a krypton-filled unit with a visible light transmittance of 0.53 and solar heat gain of 0.38--not bad for three layers of film. And Southwall can incorporate different films and coatings depending on need. This glass is available in Duxton fiberglass windows.

A high-performance window retrofit

PPG had another interesting window, a retrofit window named Renovate that is sold through Berkowitz, LLC. There are a lot of single-glazed, energy-wasting commercial windows out there, and replacing them is expensive. These retrofit windows install on the interior, and are made from PPG's low-e glass, low-e coating, and a ½" argon-filled space. A spacer containing a desiccant separates this unit from the original pane. This system takes a ¼" single-pane monolithic window and improves the center-of-glass U-factor from 1.03 to 0.16. Renovate can be installed with minimal disruption to building occupants.

Cost-competitive triple glazing

Traco, a division of Kawneer, had its OptiQ triple-glazed windowat Greenbuild as well. Developed with assistance from the U.S. Department of Energy, this window has center-of-glass U-factors of 0.17 and 0.22 for fixed and operable units. According to the company, these are commercially available windows, and unlike some high-performance windows, are cost competitive because Traco makes the entire window and does not outsource the glazing.

Thermochromic self-tinting panes

One of the most interesting window products at the show was Pleotint, a thermochromic "Sunlight Responsive Tinting" (SRT) film that is sandwiched between two layers of glass and installed as the exterior panel of glass in an IGU. You could see Pleotint at three different booths: Pleotint's (of course), PPG's (which is co-marketing Pleotint), and Southwall, which is incorporating the material into its glass units.

In general, Pleotint is clear in indirect light and tints in direct sunlight, but more specifically it reacts to temperature. It is at its darkest at 149°F (65°C) and is clear again at 77°F (25°C). Pleotint's tint range cannot be adjusted for temperature, however, and there are still questions about performance in extreme climates and lifespan, but this is a promising technology that offers a lower-cost, less complicated option to electrochromic tint windows.

Next week we'll take a look at a couple of natural insulation options, water-efficient products, and some interesting uses of recycled content.