Green Product Category: Insulation

Insulation is one of the most important components of any environmentally responsible building because it reduces energy consumption and the pollution that usually results. In this sense, any insulation material is a “green” product.

Good design and appropriate levels of insulation can minimize, or even eliminate, the need for central heating and cooling in many buildings. Insulation is a key part of the building envelope and an important element in the entire building as an integrated system. Choosing an insulation material should include considering how it works with the rest of the wall, roof, and floor system—and what additional functions, such as air-sealing, the material might serve.

A few guidelines and issues to consider when pairing insulation materials and structural elements for maximum efficiency:

• Different types of insulation also have varying impacts in terms of their raw materials and manufacture. These life-cycle impacts should be considered along with factors such as R-value, air-sealing ability, and cost.
• The quality of installation also makes a big difference in how well insulation performs. If insulation is not installed properly, it will not achieve the energy savings its rated R-value would suggest. A California study concluded that a 4 percent void in fiberglass batts resulted in a 50 percent decrease in insulation effectiveness.
• The type of structural framing also affects the performance of insulation. Steel studs conduct heat much more readily than wood studs, so they create thermal bridging that can bypass insulation installed in the cavities. Steel-framed exterior walls should have insulative sheathing installed over the framing members to reduce this problem—in fact, the U.S. Department of Energy recommends that insulative sheathing should be used with steel framing in all U.S. climates.
• Fiberglass insulation is the standard in the industry today. High-density fiberglass makes the same wall cavity 15 to 20 percent more effective in reducing heat loss. Most fiberglass manufacturers now incorporate at least 30 percent recycled material, and some products are third-party certified for their recycled-glass content.
• The potential for health problems due to fiber shedding is controversial. Loose fill is a greater risk than batts in this regard. While concern has been expressed that airborne fibers might be carcinogenic, those concerns have been allayed to some extent in recent years. Most fiberglass batts are manufactured with phenol formaldehyde as a binder, though some products use alternative binders or no binder at all.
• Cellulose insulation is primarily made out of recycled newspaper, though not always from post-consumer sources. When it is damp-sprayed into open cavities, or blown into closed cavities at relatively high density, it forms a good infiltration barrier that adds to the airtightness of the house—and it‘s less contractor-dependent for quality control in filling voids than fiberglass batts.
• Rigid foam insulation applied to framing yields added infiltration resistance, reduced frame conduction losses, and higher overall wall R-value. Extruded polystyrene (XPS) and polyisocyanurate (polyiso) rigid foam insulation used to be made with ozone-depleting CFC blowing agents, but when ozone depletion was identified as a major environmental problem, the CFCs were replaced with HCFCs through international agreement. HCFCs were eliminated from polyiso insulation as of 2003, but they are not scheduled to be totally eliminated from XPS until 2020. Polyiso is currently produced with hydrocarbon blowing agents.
• Expanded polystyrene (EPS) rigid foam has long been made with non-ozone-depleting pentane rather than HCFCs.

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