Sustainable insulation materials include things that are rapidly renewable and non-toxic. Have you ever worked with fiberglass insulation? It can get up your nose and cause your hands and any exposed areas to itch. It can get into your lungs and cause complications. Sustainable insulation is made from natural products such as wool, cotton, and soy-based foam insulation. Below, we break down the qualities and benefits of these three new types of sustainable insulation for residential construction.
Wool is natural, renewable, and sustainable. You can shear a sheep and 6 months later, it has re-grown its coat.
Wool insulation can absorb moisture without compromising its thermal efficiency. When wool fibers absorb moisture, they generate heat. This warmth acts to prevent condensation in construction cavities by maintaining the temperature above the dew-point in damp conditions.
Sheep wool insulation is safe to touch and requires no specialized safety clothing or equipment, making it easy and safe to install. Wool does not support combustion and will extinguish itself in the event of fire. Sheep wool insulation does not settle due to the elasticity of the wool fibers, so there is no loss of performance over time.
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Cotton insulation is made from recycled cotton textiles, such as denim. It is rapidly renewable, as you can harvest cotton and it doesn’t take long to grow a new crop.
Other benefits of cotton insulation are:
- It doesn’t require any warning labels;
- No respiratory or other safety equipment is required;
- It has good acoustical properties;
- It requires little energy to manufacture.
Boron, a non-toxic fire and pest resistant treatment, is used as a treatment on the cotton insulation. Unlike fiberglass, there is no formaldehyde off-gassing to be concerned about.
Soy-based foam insulation
This sustainable foam insulation is sprayed into a house in a liquid form. As it hardens, it expands up to 100 times its size. It fills in all the cracks and spaces inside the walls, making an airtight seal. It is non-toxic and moisture resistant. It resists mold, fungus, and rodents.
With soy-based foam insulation, you can get high R-values in less space than batt insulation. Open-cell type foam insulation is less dense and contains more airspace. This is less expensive and will yield about an R-3.5 per inch of insulation. Closed-cell type is denser and heavier. It is more expensive but will yield between an R-6.5 and 7.0 per inch. Soy-based foam insulation costs more to install because of the more complicated spraying procedure but will save considerably in energy bills over time.
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Editor’s note: This post was originally published on October 16, 2020 and updated on July 1, 2022.