Using materials recovered from the waste stream typically results in less waste, pollution, and energy use than using virgin materials. From an environmental standpoint, post-consumer is typically considered preferable to pre-consumer recycled content because post-consumer recycled materials are more likely to have been diverted from landfills.
In some cases, we consider products with recycled content green but with some caveats regarding where they should be used. For example, rubber flooring made from recycled automobile tires should not be used in most fully enclosed indoor spaces due to the likelihood of VOC emissions.
Recycling can have downsides. For example, some studies show that curbside collection programs and some recycling processes use more energy than they save. Closed-loop recycling is generally preferable to “down-cycling,” in which a lower-grade material is produced—but due to contamination of waste streams and the difficulty of extracting high-value ingredients, down-cycling may be as good as it gets. At times recycling can re-introduce hazardous components. Some products, like copper and aluminum, include a high level of recycled content as a matter of course—which we applaud, but don’t consider justification for listing in GreenSpec. As more complete life-cycle information on recycled materials and processes becomes available, we use that to increase our scrutiny of recycled products.
SmartBlock
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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. -
Background noise, whether from indoor or outdoor sources, adds to stress and discomfort, and poor acoustical design inside can exacerbate problems from background noise and reverberation of sounds. Products that absorb sound and prevent sound transmission can be considered green, although there are so many such products available that we also look for especially innovative products, as well as products with additional green attributes such as recycled content and strong energy performance. We also look for sound-masking systems with exceptional performance characteristics.
SmartBlocks, made from EPS, are available to form a solid concrete wall in 3.75", 5.75", 7.75", 9.75", and 11.75" thicknesses and larger custom-made thicknesses, or as a screen concrete wall measuring 40" x 10" x 10" with a 6-1/2" wide (standard size) post-and-beam concrete-core structure. SmartBlock walls possess superior acoustic insulation and use plastic connectors with 100% recycled content. ConForm Global claims R-22 to R-24 insulation values.
Insulating concrete forms (ICFs) provide a labor-efficient means of making insulated poured-concrete walls. ICFs are permanent forms—they aren’t disassembled after the concrete has cured. Most of these products are made from expanded polystyrene (EPS) foam, which has a very low global warming potential (GWP); several are made from extruded polystyrene (XPS), which is currently blown using a high-GWP HFC blowing agent, and a few are a composite of wood waste or EPS beads and portland cement.
Both EPS and XPS are produced from benzene, a known carcinogen) and both currently contain the brominated flame retardant HBCD, which is a persistent, bioaccumulative toxin. To protect against potential damage from wood-boring insects, some EPS foam used in ICFs contains low-toxicity borates.
Due to their high GWP, GreenSpec does not list XPS-based ICFs. GreenSpec does list some EPS-based ICFs, despite our concerns, because of their energy performance and other environmental attributes, such as the reduced portland cement use compared to conventionally formed concrete walls.
Be aware that the R-values claimed by ICF manufacturers are not always arrived at in a consistent manner and may be misleading. We recommend only using “steady-state” R-values for comparing products, when that information is available.
Mass-enhanced or “effective” R-values are only relevant in certain climates or under certain conditions, but they’re often listed in product literature in a way that fails to distinguish them clearly from steady-state R-values. In general, claims about the benefit of the thermal mass in ICFs may be exaggerated; the insulation interior to the concrete core of some or most ICFs dampens the ability of the concrete thermal mass to transfer heat to and from the interior environment of the building—and it’s this heat transfer that is key to effective use of thermal mass. Due to these issues, some ICF products may be excluded from GreenSpec because of misleading energy performance information from manufacturers.
LEED Credits
EAc1: Optimize Energy Performance
EAp2: Minimum Energy Performance
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