Having a well insulated house is one of the best things you can do to green your home. The more we heat and cool our homes, the more money we spend, the more resources we consume and the more greenhouse gases we emit into the atmosphere.
An Insulation Overview
The EPA estimates that approximately 4 metric tons of CO2 equivalent are emitted each year from US residences – a large percent of which is related to heating and cooling. To save energy and money, the best way to improve our heating and cooling efficiency is to ensure we have good insulation.
Most insulation takes the form of trapped air, whether in the bubbles of foam or in fiberglass or cellulose fibers. The greenest choice will have the fewest chemicals that offgas, the lowest impact during the manufacturing process, good stability so that it doesn’t settle and good fire resistance.
The environmental sustainability of traditional insulation is limited. Conventional fiberglass insulation is a suspected carcinogen and is typically produced using new rather than recycled materials. The fibers are painful – touching fiberglass insulation leaves an itching, burning sensation as those fibers lodge themselves below the skin. Fiberglass insulation dust becomes airborne during installation and can become embedded in the lungs. Finally, the chemicals used to bind fiberglass batting together are often petroleum-based and are suspected to “off-gas” toxic phenol, formaldehyde, and VOCs (volatile organic compounds).
Blue Jean Insulation
Blue Jean Insulation contains post-production denim – diverting the scraps and waste material from the manufacturer from landfills. Off-gassing isn’t a problem because it’s formaldehyde- and VOC-free. It doesn’t contain fiberglass so it won’t cause itching or skin irritation during installation. The denim batts offer high quality thermal and sound control performance. The R-Value is higher than that of fiberglass insulation – 3.5”-thick fiberglass insulation has an R-Value of 10.9, while the denim insulation is rated at 13.
In the past, people most often have complained about the difficulty in cutting the material. This has now been resolved by the manufacturer with a series of perforations in most common “off size” pieces with no cutting required. Just like fiberglass batts, denim insulation doesn’t expand into cavities. This can lead to gaps in places.
Cellulose insulation is made from recycled newspapers and treated with fire retardant. It’s different from familiar batt insulation — it’s fill insulation. This means that it is pumped in with vacuums into walls, attics, and ceilings.
A substantial benefit of cellulose insulation is that it fills every nook and cranny as opposed to batts which can leave gaps between pipes and beams that can result in reduced insulating efficiency.
Cellulose insulation gets points for recycled content, good thermal performance, lack of formaldehyde, cost effectiveness, and inflammability plus it uses less energy than fiberglass to manufacture. Unlike batts which require removal of the drywall, you can retrofit walls with dry-fill cellulose by cutting a small hole (which is later patched) in between each stud at the top of the wall and blowing in the insulation. Fiberglass insulation prices are about 7 cents per inch thick square foot. The cost of cellulose insulation pricing is about the same.
At R 3.6 to 3.8 per inch, blown-in cellulose insulation is better than fiberglass insulation which has an R-value of about 2.2 to 2.6. But R-value is only one factor in the energy efficiency of a home. Studies of actual buildings regularly show that cellulose-insulated buildings may use 20% to 40% less energy than buildings with fiberglass, even if the R-value of the insulation in the walls and ceilings is identical. One reason for this is the capacity of cellulose to stop air infiltration and heat-zapping convective air currents within your walls and ceilings, which are inherent with most fiberglass insulation.
The downside of cellulose is that it it’s not DIY friendly. It may sag over time (which reduces its efficiency) and it can absorb moisture. Typically, this is not an issue in an attic where heat and ventilation can promote drying. It can be a problem in walls. For example, a plumbing leak that would ordinarily be immediately apparent through your drywall can be absorbed and wicked through the entire cavity before making itself known.
Spray Foam Insulation
Spray Foam Insulation is sprayed in place and expands up to 100 times its original liquid size creating millions of tiny air pockets that result in highly effective R-values. Spray foam penetrates every cavity and even the tiniest crevasses for a perfect air-sealed fit, creating a tightly sealed home when properly applied.
There are different types of spray foam; closed or open cell, polyurethane or soy based, even a concrete type product called Air Krete. Look for spray foam products that do not contain harmful chemicals.
Closed-cell foam has a higher R-value (about 6R per inch), but is more expensive than open-cell (which is about 3.5R per inch). airKrete claims an R-value of 3.9/inch. The high R-value-per-inch of closed-cell foam makes it a good choice if you have limited space
Spray foam provides the tightest seal, excellent thermal performance, and can easily be applied to attic ceilings, creating an insulated space for a/c ducting and pipes. It also prevents moisture transmission better than just about any other insulating material.
Spray foam usually costs more than traditional batts or cellulose (around $1-$2.00/sq foot), and is not an easy project for a do-it-yourselfer. As with all non DIY insulation materials, look for professional installers with a track record of working with your product.
In My Opinion
From my research, the best bet for total building insulation, assuming price is not the primary concern, is spray foam.
Best for sound dampening (between floors or in plumbing walls) is blue jean insulation or airKrete spray foam.
If budget is your main focus, cellulose beats fiberglass for performance and non-toxicity.
Tell Us What You Think
Have you used one of the insulation products mentioned here? What were the characteristics that influenced your choice?
Have I missed an insulation product that you think should be considered with this set? Leave a comment and let me know what you think.