Some materials provide a better alternative in an application dominated by products for which there are concerns about toxic constituents, intermediaries, or by-products. With the panoply of products made with polyvinyl chloride (PVC) and brominated flame retardants, some products are green simply because they provide an alternative. Examples of this are natural wall coverings, drain and vent piping, and roofing membranes. Some green products are free of hazards common to the product category; for example, LED lighting is inherently free of the mercury found in fluorescent lighting sources.
However, it’s worth noting that without transparency about actual ingredients, there’s no guarantee that a product won’t have less common or less well-known hazards that the manufacturer isn’t talking about. We use Pharos’s Chemical and Material Library to assess less well-known hazards, and we encourage manufacturers to review the hazardous properties of all chemicals they use and seek out safer materials.
Agepan Functional Wood
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Moisture brings durability and air quality problems with it, and myriad green products are designed to manage it and keep it out. Given the variety of products available, we look for those that meet key performance standards and that make sense in a whole building assembly—such as vapor-permeable weather-resistive barriers that not only prevent moisture from entering the building envelope but also allow drying when the envelope gets wet.
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Better information alone doesn’t make a product green, but it does make it a lot easier to see just how green that product actually is. We can make more informed purchasing decisions when we know what’s in a product, not just manufacturer’s claims about what it’s “free-of”; and when we know the actual environmental impacts of manufacturing the product relative to alternatives, not just a trade association’s claim that it’s “green.” Making information public can also help manufacturers get greener. It’s often the manufacturers that are already greener that are willing to share more information in the first place, but in the process of doing so they see where they still need to improve. Products with Environmental Product Declarations are included here, along with products with other forms of disclosure, such as products from companies that participate in the Global Reporting Initiative, or provide full disclosure of ingredients, potentially via the Health Product Declaration format. GreenSpec also lists products that help track buildings' energy and water performance, especially when those tracking tools can be used to publicly display or report energy and water usage.
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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.
Agepan, manufactured in Germany by Glunz AG and imported in North America by several Passive House building product dealers, is a line of vapor-permeable wood fiber products. Agepan THD, an insulation appropriate for both interior and external applications, contains no added formaldehyde, though it is bonded with PMDI, an isocyanate. Agepan THD has an R-value of R-3 per inch. It is available in a variety of sizes and thicknesses, as well as in either square edge or tongue and groove styles. Other products include floor and roof panels, OSB, and cellulose insulation. An EPD was conducted for Agepan in accordance with ISO 14025 and is available for review via the German Institute of Construction and Environment here (PDF).
Sheathing comprises a significant portion of the materials used with many building types. Careful consideration of product selection and use can reduce the environmental impacts of a project.
Wall sheathing is often used only as an additional layer of weather protection, although it may also be required for racking resistance. When let-in diagonal bracing is used to provide racking resistance, wood-panel sheathing can sometimes be eliminated or replaced with more resource-efficient or insulative products.
Phenol-formaldehyde (PF) binders are used in plywood, while OSB can be made with PF or the non-formaldehyde-emitting methyl diisocyanate (MDI), a polyurethane binder. Ironically, exterior-rated products using PF binders are less of an offgassing concern than interior-grade panels made with urea-formaldehyde.
Oriented-strand board (OSB) can be an efficient use of forest resources because it can be produced from small-diameter or low-grade tree species. Wood products can carry the “FSC Mixed” label under a percentage-based standard based on the average certified and non-certified throughput of the facility at which they are made.
Products listed here have one or more of the following attributes: FSC-certification; nonformaldehyde binders; relatively nontoxic borate preservative treatments; or other environmental advantages over conventional OSB and plywood.
GreenSpec lists products in this section that provide insulating qualities, often through the incorporation of a radiant barrier. When they face a heat source, radiant barriers work by reflecting heat.
When faced away from a heat source, radiant barriers function primarily by virtue of their low emissivity. This means that the surface does not radiate heat well. A radiant-barrier surface on roof sheathing, for example, heats up from the sunlight striking the roof, but that heat energy is not readily emitted into the attic space—so that attic remains cooler. This is why the radiant barrier seems to "reflect" heat back out of the building. An air space is required on at least one side of a radiant barrier in order for it to function as designed.
Radiant barriers in attics are most beneficial in reducing cooling loads; their effectiveness in reducing heating loads is more limited. Radiant barrier products usually do not include significant recycled content, because of the lower reflectivity of recycled aluminum and the difficulty in producing very thin foils from recycled aluminum; the high embodied energy of virgin aluminum can be recovered through energy savings.
When comparing products, look for the lowest emissivity (which corresponds to the highest reflectivity); for example, Polar-Ply radiant barriers have an emissivity of 0.03. Do not rely on "effective" or "equivalent" R-values, which are only relevant in certain climates or under certain conditions.
The structural specifications of insulating sheathing boards vary—when incorporating these products into your design, make sure that they provide what you need.
Subflooring creates the structural plane of the floor, over which the finish flooring layers are applied. Phenol-formaldehyde (PF) binders are used in plywood, while OSB can be made with PF or the non-formaldehyde-emitting methyl diisocyanate (MDI), a polyurethane binder. Formaldehyde emissions from these structural products are exempt from major North American emissions standards, including those from the U.S. Department of Housing and Urban Development (HUD) and the California Air Resources Board (CARB).
Oriented-strand board (OSB) can be an efficient use of forest resources because it can be produced from small-diameter or low-grade tree species. Some subflooring products combine the function of a subfloor and underlayment, reducing material use. Products listed here contain no-added formaldehyde (NAF) or are available with FSC-certified content. Magnesium oxide panels, which are particularly insect and moisture resistant, are also listed here.
Rigid board insulation, usually made from plastic foam, glass fibers, or mineral wool, is a critical component in many new or retrofit energy-efficient buildings. Rigid board insulation typically provides high R-value for a given thickness and can be applied across the surface of walls, roofs, or foundations to reduce thermal bridging through framing, foundations, and other structural components.
Foam board insulation is petroleum-derived and uses a blowing agent for expansion. Polyisocyanurate—or “polyiso”—foam board typically has foil facing and has the highest R-value of any common insulation material. Polyiso boards are made with hydrocarbon blowing agents that are non-ozone-depleting and have negligible global warming potential (GWP).
Extruded polystyrene (XPS) is non-ozone-depleting, although XPS in North America is produced today with a blowing agent (HFC-134a) that has high GWP. (Most European manufacturers have converted to very-low-GWP hydrocarbon blowing agents, while North American manufacturers have been unwilling to have the R-value per inch drop as a result of a similar change.)
XPS and expanded polystyrene (EPS) are manufactured using a number of hazardous chemicals, including benzene and the brominated flame retardant HBCD—which is a persistent, bioaccumulative toxin that is slated for elimination in Europe. Because of the health and environmental concerns surrounding these materials, GreenSpec does not list rigid polystyrene insulation as a stand-alone product. However, because energy performance is a high priority with any building, use of XPS or EPS may be appropriate when those are the only options available.
Alternatives to rigid foam include rigid mineral wool, rigid fiberglass, and foamed cellular glass. It may also be possible to redesign building enclosure systems to utilize spray polyurethane foam (SPF) or minimize thermal bridging in other ways so that cellulose or other fiber insulation products can be used without an energy penalty.
Mineral wool board is a versatile insulation made from molten slag (a waste product of steel production) or natural rock (such as basalt or diabase), held together with a phenol formaldehyde binder. Mineral wool has a higher density than fiberglass, is more resistant to fire, and is better at blocking sound. It is appropriate for foundation wall insulation and, in highest-density form, may be considered for use under concrete slabs (although such applications may need special approval by building officials).
While expensive, cellular glass (Foamglas) is another option. Its high compressive strength and moisture properties make it appropriate for below-grade applications, especially sub-slab applications where XPS currently dominates the market.
Rigid fiberglass is made similar to fiberglass batts, but formed into denser boardstock. A shift to a non-formaldehyde binders has not been as rapid with rigid insulation products as it has with batts, but some manufacturers are making that transition. Concentration of the binder is higher in rigid boardstock than in batt insulation.
Note that board insulation products vary widely not only in R-value but also in permeability, moisture resistance, insect resistance, fire resistance (and need for flame retardant additives), and end-use applications. Selection of these products can be complex and confusing. More detail is offered in the BuildingGreen Guide to Insulation Products and Practices.
Products listed here have at least one of the following attributes: post- and/or pre-consumer recycled-content, reduced off-gassing, avoidance common hazardous ingredients, high durability, and blowing agents with little or no global warming potential.
LEED Credits
EAc1: Optimize Energy Performance
EAp2: Minimum Energy Performance
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