Consider Cellulose

May 25, 2011
Is cellulose a sustainable insulation alternative for your next project?

The definition of "sustainable" can differ from person to person, as it has no set definition when applied to building products and practices. In fact, a sustainable product for one building project may not be sustainable for another.

This includes building insulation. There are many relatively new types of insulation that are touted as "sustainable." How can you be sure that cellulose insulation is a viable eco-friendly alternative for your building?

After waning in popularity, the recent green revolution has made cellulose insulation a hot alternative.

"We think cellulose is 'traditional' insulation," explains Daniel Lea, executive director of Cellulose Insulation Manufacturers Association. "It has been around in its modern form (i.e. recovered paper fibers with fire retardants) since the 1920s. If you include all cellulosic materials that have been used as insulation throughout history, it goes back thousands of years. Every thatched roof cottage or hut is insulated with cellulose; Thomas Jefferson used a form of it in Monticello."

Insulation Impacts
Determining the sustainability of a product requires consideration of the product's entire life cycle. "When it comes to insulation, you need to consider the full life-cycle of the product, which includes both embodied impacts and use-phase impacts,'" says Simpson Gumpertz & Heger Inc.'s Mark Webster, project manager.

Cellulose Insulation at a Glance
Installation methods Loose-fill, wall-spray (damp), dense pack, stabilized
R-value per inch 3.6-4.0
Raw materials Old newspapers, telephone directories, borates, ammonium sulfate
Pollution from manufacture Negligible
Indoor air quality impacts Fibers and chemicals can be irritants
Comments High recycled content and very low embodied energy


"The embodied impacts are due to manufacturing and installing the insulation at the start of the building lifespan, as well as disposal impacts when the building is no longer needed," he continues. "The use-phase impacts for insulation may be measured by the energy savings over the life of the building that the insulation affords. There are generally tradeoffs between these two life-cycle phases: insulation products with low embodied impacts generally have lower R-values per inch, while those with high embodied impacts have higher R-values per inch. Thus, you need to use more of the former to achieve the equivalent insulating value of the latter."

Cellulose Is Competitive
For instance, "cellulose has very low embodied impacts and high recycled content," says Webster. The average R-value of cellulose insulation is competitive to the average R-values of more traditional insulations, such as fiberglass and mineral wool. However, the R-values for these are on the lower end of the insulating spectrum. So while cellulose has low embodied environmental impacts, its R-value is on the low side.

The competitive pricing and R-values that are in line with other traditional alternatives make cellulose insulation appealing. But knowing that it can serve more than one purpose can make it especially attractive and present a more sustainable choice. Could it serve as insulation and the solution to your acoustics problems? Loose fill cellulose insulation provides fire protection and acoustical benefits in apartments, hotels and motels, and multi-tenant attached commercial structures, Lea explains. Cellulose commercial spray is also commonly used for acoustic, fire protection, and thermal purposes in factories, exhibit halls, gymnasiums, auditoriums, parking garages, and other similar structures.

As with traditional insulations, exposure to moisture can be a problem. "It is an organic product and must be well protected from moisture," says Webster. "Additional attention to design and installation, and even additional water-protection materials, may be required to protect this product. As mentioned, the moisture present at installation must also be carefully managed."

Your definition of "sustainable" could even differ from project to project. "In some cases, the most 'sustainable' choice may be to use an insulation with high-embodied impacts but that offers excellent energy performance," Webster explains. "If the building is known to have a relatively short lifespan, then embodied impacts are relatively more important and the durability less important, which would make products such as cellulose more attractive."

Kylie Wroblaski ([email protected]) is associate editor of BUILDINGS

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