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.
Comfort-Zone
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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.
Comfort-Zone cellulose is 82% post-consumer recycled newsprint treated with borate. This product also contains a proprietary dust inhibitor. Ideal for attics, ceilings, and walls as loose-fill or sprayed insulation, Comfort-Zone is available within 400 miles of the plant.
Blown insulation can be any fiber insulation material that is blown into place, usually in a wall cavity or attic. The most common blown insulation materials are cellulose and fiberglass, but mineral wool, sheep’s wool, and other materials are also used.
Cellulose insulation has several environmental advantages. Most products contain 75%–85% recycled newspaper (usually post-consumer) and borate and/or ammonium sulfate flame retardants, which are benign in comparison with other common flame retardants.
Dry cellulose can be blown into a closed framing cavity in a “dense-pack” application, or blown or poured into the floor cavity of an attic or ceiling. “Stabilized” cellulose, used primarily in attic floor applications, contains a small amount of acrylic binder to prevent settling and shrinkage. For information on damp-spray cellulose, see 07 21 29 – Sprayed Insulation. Rental equipment is commonly available for applying loose-fill cellulose, while hiring a contractor is necessary for a dense-pack application.
The energy performance of dense-pack cellulose is comparable to that of high-density fiberglass batts at roughly R-3.7 per inch, but cellulose insulation generally fills cavities more completely—especially around wires or pipes, or in oddly sized framing cavities—and so is more effective at preventing convection heat losses.
Loose fiberglass is most commonly blown into closed cavities or applied through a specialized mesh that has been stretched across the inner face of framing members; a form including binder can also be sprayed into an open cavity (see also 07 21 29 – Sprayed Insulation). Fiberglass and mineral wool can release respirable fibers into the air. While these fibers are less likely to be carcinogenic than they were in older formulations, they are respiratory irritants. Blown fiberglass and mineral wool should only be installed if the fibers can be prevented from getting into occupied space or air distribution systems.
Products listed here have recycled content, are derived from agricultural waste, offer superior moisture or air leakage performance, or impart lower indoor air quality concerns than other products.
Many insulation materials that are installed as loose-fill can also be spray-installed when mixed with moisture or a binding agent (or both). Some are sprayed into open cavities and then covered, as with damp-spray cellulose or fiberglass with a binder, while others are sprayed onto exposed surfaces and left exposed. With cavity-fill installations, a special “screeding” tool is used to trim off excess insulation flush with the inner face of the framing members.
Spray-insulation applications are typically very effective at reducing air leakage in addition to reducing conductive heat loss or gain. These materials also do a good job around wires and pipes that run through framing cavities—thus solving a common installation problem with batt insulation.
Sprayed insulation can be used on its own in framed walls, although thermal bridging may be a problem. A layer of rigid board insulation (see 07 21 13 Board Insulation) is often used with cavity-fill sprayed insulation to provide a thermal break. Or, a framing system can be used that results in minimal thermal bridging, such as a double stud wall separated by an air space, or a deep, non-structural “curtain-truss” or modified Larsen Truss frame that hangs off a structural wall.
With systems that add moisture, make sure that the installer will keep the moisture level at or below the level specified by the manufacturer. With damp-spray cellulose, which has the highest moisture content of these systems, some drying should be permitted before drywall is applied. Manufacturers typically recommend at least two days of drying before drywall installation, though more time may be required in areas with high humidity, or dryers or dehumidifiers may be called for.
Products listed here have high recycled content, offer superior energy performance, or avoid potentially hazardous binders.
More detail is offered in the BuildingGreen Guide to Insulation Products and Practices.
LEED Credits
EAc1: Optimize Energy Performance
EAp2: Minimum Energy Performance
MRc4: Recycled Content
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