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.
SeriousWindows 600
The SeriousWindows 600 line of vinyl windows from Serious Energy are available in several styles, including double hung, casement, and sliding. These energy-efficient windows achieve U-factors as low as 0.14, SHGC values ranging from 0.19–0.28, and VT values ranging from 0.38–0.53. The windows have dual weatherstripping for increased airtightness, as well as argon or krypton gas fill and a suspended film for increased thermal performance. SeriousWindows are available in several grille options and frame and hardware colors. Serious Energy offers a lifetime limited warranty and a glass breakage warranty.
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.
LEED Credits
EAc1: Optimize Energy Performance
EAp2: Minimum Energy Performance
EQc8.1: Daylight and Views—Daylight 75% of Spaces
EQc8.2: Daylight and Views—Views for 90% of Spaces
IEQc2.4: Daylight and Views
IEQc8.1: Daylight and Views—Daylight
IEQc8.2: Daylight and Views—Views
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