January/February 2011- EcoHome Magazine
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Vinyl is by far the most hotly debated cladding material among green building professionals, caught between its detractors and its defenders. On the one hand, vinyl siding is often selected for its affordability, low maintenance, and durability, with a 40- to 50-year life expectancy. And it is lightweight in transport. On the other hand, it’s made from PVC, an ingredient many green advocates question.
|According to vinyl siding advocates, next to its durability, vinyl’s key environmental attribute is its ultimate recyclability. “Vinyl siding can be recycled into vinyl siding many times,” says Tad Radzinski, president of design and development firm Sustainable Solutions and a consultant to the Vinyl Siding Institute (VSI). After teardown, vinyl siding can be remanufactured, with no separation required between manufacturers. Though no significant national reclamation program exists yet, some companies (CertainTeed, for example) are beginning to implement programs.
In the life-cycle assessment the Vinyl Siding Institute commissioned Sustainable Solutions to conduct using BEES, vinyl performed better than brick and stucco, although it finished after cedar (the LCA did not include fiber cement because that data was not available in BEES at that time). A life-cycle assessment performed by a third party for the Western Red Cedar Lumber Association, which did include fiber cement, found similar results and also ranked vinyl ahead of fiber cement.
The chief concern about vinyl siding within green building circles and among health advocates centers on PVC’s chemical makeup. The Healthy Building Network, for example, labels PVC an “environmental health disaster” and states that PVC poses hazards in manufacturing, its life, and disposal, and releases gases and dioxins if burned by accident or as waste. And the Living Building Challenge, seen as the country’s most stringent green building certification program, includes PVC in its “Red List,” making it one of 14 product ingredients restricted from use.
Jery Huntley, president and CEO of the VSI, says that once the siding is manufactured, the chlorine is locked into the product more tightly than when it was salt. “Vinyl siding is safe,” she asserts. “It does not release chemicals into the atmosphere. The products of vinyl combustion are no more hazardous than those produced by burning many other common materials, both synthetic and natural.”
Huntley says the LCA shows vinyl having lower environmental impacts compared to many other exterior claddings, including lower levels of toxic chemicals released into the environment. “Vinyl siding does not off-gas or emit chemicals during its lifetime,” she says. “During its lifetime, it doesn’t require painting, staining, or caulking. This further reduces emissions over the life cycle that could occur from the release of harmful solvents and other VOCs into the environment from painting and staining.”
The latest trend within the category has been the introduction of insulated panels, which have a layer of EPS foam adhered to the back. The foam reduces thermal bridging and, according to the NAHB Research Center, can add an additional R-value of up to 4.5. The backing also adds rigidity and impact resistance.
The foam backing does bring another virgin material to the manufacturing process, but it can be recycled upon teardown after it’s separated from the vinyl panel.
VSI offers a certification program that independently verifies that products meet or exceed the industry standard for quality, ASTM D3679, which covers impact, thickness, and weatherability; it was recently upgraded to require no lead or cadmium content after some products were imported with those elements.