Part3 in my series – "How to build a better house". Last week we talked about advanced framing techniques, which in simple terms replaces lumber with insulation material and maximizes the wall that’s insulated. This effectively improves the thermal resistance or R-value of a wall. As a reminder on how important advanced framing is, let's look at the comparison of a standard wall vs a wall constructed with advanced framing again:

A standard wall assembly using R-13 batt insulation will have an effective R-value of 11.1. An "advanced" wall assembly will have an effective R-value of 14.6 or 30% higher than the traditional wall. 

This week I want to focus on the different kind of insulation materials we can use to use that give you the most energy efficient green home.

In general, insulation is one of the most important components in any responsibly built structure, especially in green buildings. Insulation reduces energy consumption and if properly installed, can reduce draft dramatically. From that perspective, any insulation material is a “green” product.

The choice of insulation material will be covered in my next article "Insulation techniques……or how to build a better house – Part4" and has a lot to do with where the insulation is installed (wall, ceiling, roof, crawlspace etc etc), the climate area you live in and the specific details of your wall assembly.

So let's look at some of the different kinds of insulation materials that are out there these days:

Fiberglass Insulation:
This is the standard in the building industry today. High-density fiberglass makes the same wall cavity 15 to 20 percent more effective in reducing heat loss. The majority of manufacturers now incorporate at least 30 percent recycled material, and there are quite few products that carry third-party verifications for their recycled-glass content. If Fiberglass insulation is used as a batt, it is important to know that most of them are manufactured with phenol formaldehyde as a binder, though some products use alternative binders or no binder at all. So be sure and investigate the contents of the product you want to use in your green home.

Cellulose Insulation:
Is primarily made out of recycled newspaper, but not always from post-consumer sources. It is often damp-sprayed into open cavities, or blown into closed cavities at relatively high density. Cellulose adds to the airtightness of the house—and by forming a good infiltration-barrier. It is also less quality control dependent in filling voids than fiberglass batts (in simple terms… not as easy to mess up

Rigid Foam Insulation:
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.

Spray-Polyurethane Foam insulation:
One of my favorite insulation materials, spray-foam is an excellent choice for most buildings. Though slightly more expensive than the other materials mentioned above, the qualities of spray-foam will give you "a lot of bang for your buck". As the name implies, it is sprayed into open cavities and quickly expands to about 100 times its original volume. Most manufacturers claim R-values of about R-3.8 per inch. Several manufacturers sell water-blown products though there are still quite a few that use HCFCs or hydrocarbon blowing agents which are harmful to the environment and your health. So again, beware of what you buy.

Of course, there are a myriad of products available on the market today. If you want detailed information, I have included some manufacturer links below. If you want to find out specific product details while you are in the process of building your home, try the product directory at http://GreenBuildingAdvisor.com (Paid subscription) or http://www.buildinggreen.com/ (Paid subscription). They have great product databases with all the relevant product information.

I should mention that most of these materials can be installed in different ways – Loose fill, batts, spray or rigid boards. What to use "where" and "why", will be covered in my next article.

Be sure and come back. Don't miss next week's article. Insulation Techniques… or “How to build a better house” – Part4

Links to other articles in this series:

Thermal Bridging… and how it affects a wall assembly – Part1

Advanced Framing Techniques – Part2

Some Manufaturer Links:

http://www.certainteed.com/- Fiberglass

http://www.applegateinsulation.com/ – Cellulose

http://www.knaufinsulation.us/ – ECOBatt

http://www.demilecusa.com/ – SprayFoam

http://www.icynene.com/

Sources:

http://www.greenbuildingadvisor.com/

http://www.buildingscience.com
http://www.toolbase.org
http://resourcecenter.pnl.gov
http://www.energysavers.gov