What's in a Wall: Insulation Reborn

Lastly in the series exploring eco-friendly options for interior walls, we take a look at sustainable alternatives for insulation best for Pacifica.

This month, PG&E announced a new rebate incentive for consumers to lower their home energy bills. Energy Upgrade CA offers tiered rebates for the roughly 60% of California homes that are under-insulated.

This effort is, in part, a response to previous energy rebate programs that, while well intentioned, did not significantly reduce statewide energy demand. Widely publicized solar rebates offered consumers a generous incentive to add solar panels to their homes, yet failed to realize that the resulting cheaper energy would affect homeowner’s energy behaviors. When they figured out that they were now paying so little for energy, solar users lost incentive to conserve energy. Window rebates had been sold as well with promises of return on investment, yet the costs of installation proved this return to be a stretch.

Insulation upgrade has real savings potential, however, and when it’s coupled with the Energy Upgrade CA rebate it represents true value for California residents seeking to reduce their utility bills.

So, what’s in a wall, really?  It may surprise you, but often nothing. Roughly 50-60% of the walls, attics, crawlspaces and garages that I inspect and remodel in San Mateo and San Francisco counties have absolutely zero insulation. The remaining homes have such poorly installed insulation that the structure is only retaining half of the heat it has been designed to.

In this light, and especially with the new incentives, now would be a good time to take a look at the number of sustainable options for home insulation. No longer are we limited to the fiberglass, health-problem-causing insulation paraded on television by the Pink Panther. Whether you’re taking advantage of California’s most recent Energy Upgrade Program or making small repairs or alterations to your home, consider these green insulation alternatives I recommend for Pacifica’s coastal climate:

Recycled Fiberglass Bats –Ideal for small projects and do-it-yourselfers, Knauf’s EcoBatt’s are made from beach sand, post-consumer recycled bottle glass (minimum 30%) and bio-based binding agents rather than petroleum binders. Most of us are familiar with traditional insulation; the EcoBatt is installed the same way. I’ve used this insulation on several homes locally and like the fact that it comes with no paper backing. This makes installation around irregular wall cavities easier, allows for a tighter custom installation of the bats, and offers greater fire protection. On the other hand, it can still break off into minute airborne pieces and cause health risks. When installing these bat insulation products, wear protective clothing, eyeglasses and a dust mask. 

Denim Insulation Bats – My all around favorite insulation material, this is about as healthy an insulation as you can get. Made from recycled blue jeans and containing no chemical irritants, UltraTouch Denim Insulation is safe enough for children to install. UltraTouch has thermal resistance similar to fiberglass bats and its boron-based fire retardants also protect against mold, mildew and fungi. The best part about this product is that when you cut it for installation, no microscopic airborne irritants are released into your home.

Icynene – Both an air sealant and insulation material, Icynene is a chemical spray-on expanding foam, similar to the canned expandable foams available at local hardware stores. Unlike many two-part spray foam sealant products, Icynene is a water based formula that, when applied, produces no toxic off-gassing. The downside to this option is that it requires a professional insulation contractor to apply and is quite expensive. I advise this in new home construction rather than remodels. 

Before you explore sources of alternative energy for your home, consider how well your home is insulated right now. If you make sure you have adequate insulation, it can reduce your home’s energy consumption without expensive solar panels or other forms of alternative energy. After all, for decades we have purchased cars based on their miles-per-gallon efficiency; shouldn’t we do the same for our homes? 

By increasing the performance of our existing homes first, future green upgrades are often cheaper and best tailored to each building. With proper insulation, solar panel installations require fewer panels to provide adequate electrical supply and furnace capacity can be greatly reduced without decreasing comfort. 

When I consult with my clients, I like to map out a sustainable retrofitting strategy starting with what is in their walls, if anything at all.

greenerjax March 17, 2011 at 08:41 PM
Dustin, you might want to check out cellulose insulation if you are a green building contractor. There is no greener insulation today for companies like yours to use to your customer's delight. Cellulose insulation is manufactured with over 75% recycled paper fiber. Fiberglass has 10X the embodied energy and foam has 64X! All insulation is green. Cellulose is the Greenest of the Green.
Dustin McGahan March 18, 2011 at 04:22 AM
Thanks for mentioning blown-in cellulose insulation! I agree that cellulose is a great insulator. By far the best option for attic spaces, that are particularly hard to insulate effectively with traditional bat insulation. Combined with foam (for air sealing) we can make homes that are tight enough to reduce their energy load incredibly. I find that there are no "one-size-fits-all" solutions when it comes to green building (and especially green retrofitting, my market niche), but rather, that each home has unique needs that require tailored solutions. With Pacifica's foggy coastal climate, unless I have the ability to install an exterior "drainage plane" underneath the siding, I hestitate to use blown in cellulose in wall cavities. One drawback to cellulose is its sensitivity to moisture. I do however, recommend blown-in cellulose rather than blown-in fiberglass, due to its higher compaction rate and lower embodied energy. Thanks for commenting, dialogue brings better solutions for our environment!


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