Before specifying efficient heating and cooling equipment, it’s important to do what we can to reduce heating and cooling loads. Insulation is one of the key products to consider here, but because there are so many insulation products on the market, we look for additional benefits. Examples include cellulose insulation with recycled content, mineral wool insulation with no flame retardants, and fiberglass insulation with no formaldehyde binders. Other products in this area are high-performance windows and glazings, products that contribute to building airtight envelopes, products that reduce thermal bridging, and window-retrofit products.
With products in this area under constant development, we are always refining our approach. For example, as we have learned about insulation products with hazardous flame retardants and blowing agents that have high global warming potential, we have removed those products from GreenSpec, pending manufacturing changes. We encourage building professionals to pressure manufacturers for those changes through specification language and purchasing decisions.
Wasco Vinyl Replacement Windows
Milwaukee-based Wasco Windows specializes in vinyl replacement windows with high-performance glazing options. Some Wasco Windows use German profiles made of PVC with glass-fiber reinforcement. These low–U-factor (between 0.19 and 0.20) profiles are available on Wasco's triple-glazed tilt-and-turn windows; their 1.38"-thick high-solar-gain triple-glazing is specifically intended for northern climates. Center-of-glass specifications for this type of glazing are U-0.133, with a solar heat gain coefficient of 0.566.
Plastic windows come in both ABS and vinyl (PVC). A selling point for these windows is that they are low-maintenance. ABS does not contain chlorine and so, unlike PVC, ABS has no risk of dioxin generation during an accidental fire or incineration at the end of the product's life.
Energy performance is GreenSpec’s primary green consideration for windows, and new developments in window technology enable today's products to far outperform those of a few decades ago. Among the improvements are multiple glazing layers, low-conductivity gas fills, better seals on insulated glazing units, heat-reflective (low-emissivity) coatings, advanced weather-stripping, and new frame systems.
Low-emissivity coatings which allow short-wavelength solar radiation (sunlight) to pass through but reflect long-wavelength radiation (heat) back into the conditioned space are now standard options from all major window manufacturers. Further improvement in energy performance is achieved with triple-glazing and multiple low-e coatings; sometimes an additional glazing layer is provided as a suspended polyester film.
While vinyl products are listed here, there are some performance concerns specifically with regard to expansion and contraction. Products listed here must achieve an NFRC-certified unit U-factor of 0.25 or lower for ABS and 0.20 or lower for vinyl and blends that contain vinyl. GreenSpec’s U-factor threshold for windows varies depending on the environmental attributes of the frame material or other features such as storm resistance.
To qualify for GreenSpec, windows with the listed U-value must not only be available, but actively marketed.
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