Insulation Options: 3 Eco-Friendly Insulating Materials

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Friends and I insulated the ceiling of a bathroom using fiberglass insulation. Everyone was itchy, but my lungs were completely congested for a few days. It was pretty scary, since I have asthma. I wondered if I’d ever get better! But I did. So it’s not good for your body.

All insulation is eco-friendly; in winter, warm air stays in, and cold air stays out. In hot weather, insulation keeps the heat out, reducing cooling costs.  Sadly, the most used insulation is fiberglass. It comes in batts or loose fill that gets blown in. Fiberglass is just what it sounds like – glass that has been made into fibers. It can cause skin irritation and respiratory problems when small pieces break off and enter the body. I’ve had this happen.


The embodied energy of fiberglass is very high. It takes a lot of fuel to manufacture and transport it. It also has a relatively low recycled content and is frequently manufactured with a resin that off-gasses formaldehyde.

If you want to have your eco-friendly insulation be more eco-friendly, what can you use? There are many alternatives on the market these days, and they are much greener than fiberglass. Here are my three favorites.

Cellulose insulation

Cellulose is one of my favorites. Cellulose is shredded paper mixed with a boric acid solution for fire resistance. It is sprayed between studs and joists reaching small spaces that fiberglass batts cannot reach. This makes it more effective in blocking air movement.

Cellulose is 100% recycled material, meaning it has a very low embodied energy and which reduces landfill waste. Think of all the paper we throw away! It could be used for very effective insulation!

Cotton batts insulation

Cotton batts are made of shredded denim and treated with boric acid as a flame retardant. Material is left over from the manufacturing process, reducing the amount of trash going to the landfill.

Denim is also all natural, recyclable and renewable. Denim batts have great acoustics, too, absorbing sound.

Wool insulation

Picture a sheep. Think of that wooly covering. It keeps a sheep warm in winter and cool in summer, because of small air pockets in the fibers. Air is a great insulator! Wool can be blown in as loose fill or used as batts for wall cavities, or as rope in smaller places. It has great acoustic qualities, is water repellant and fire and mold resistant. It is all natural, 100% renewable and sturdy. If this material weathers the outdoors, it can surely weather being put into a wall or ceiling!

Choosing eco-friendly insulation

These eco-friendly materials have R-values comparable to fiberglass batts. The R stands for Resistance to air movement. The higher the number, the better the insulating properties. Consider going green in your next renovation or in new construction. The insulating qualities will be there, you will reduce landfill trash and the emissions associated with manufacturing fiberglass, and you can lower your carbon footprint.

No matter what type of insulation you have, it saves fuel and money. Insulation reduces air movement from the inside to the outside and vice versa. Lowering energy use for heating and cooling is eco-friendly, and occupants are more comfortable in their homes. But, renewable, recycled and recyclable products will keep your house as warm or cool as fiberglass with a smaller impact on the earth. Do it!

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Nan Fischer

Nan Fischer has been living and building green for over 35 years. Nan’s emphasis on the BuildDirect blog is about how to make your dollar stretch further, while also moving toward a more sustainable lifestyle, as well as upcoming and existing technology to help us live in an ecologically-friendly way. Nan also authors posts on the website of her seed business, sweetly seeds.