12 Green Insulation Options: The Ultimate List of Natural, Recyclable, Non-Toxic Eco-Friendly Insulators

Nowadays, it seems like every product on the market claims to be “green” or “eco friendly.” But how do you know the truth? We’ve scoured the internet to find you twelve green insulation options to help you lower your carbon footprint and save on energy costs.

We’ve even found one option that’s grown from mushrooms!

1. Aerogel 

The key to energy-efficient home design is good insulation. Aerogel is a high-tech insulating material used in spacecraft that is now becoming available for residential applications. 

They make aerogels by removing liquid from gels. This process results in a substance full of tiny air pockets. These pockets make it difficult for air (and heat and cold) to pass through the material. The result is a very effective, lightweight insulator.

While aerogel works very well, it is still costly to manufacture and mostly used in industrial settings. As the manufacturing process improves and the price drops, this will become a more viable insulation option for residential projects.

2. Cellulose  

Modern cellulose insulation is made primarily out of recycled newsprint, making it one of the most affordable green insulation options for those who are tight on a budget. 

Old newspapers are shredded into tiny pieces and treated with borax. The resultant fire retardant and pest resistant fiber can be blown in as loose-fill in attics or densely packed in walls and floors. 

It is essential cellulose insulation not get wet as it will retain water and slowly settle and deteriorate. It also loses its fire-retardant properties.

3. Cotton/Denim 

Are you wondering what happens to all the leftover pieces of denim from making jeans? At least some of it gets recycled into eco-friendly insulation material. Also called natural cotton fiber insulation, this insulating material can contain 85% recycled materials (1). 

The r-value of cotton insulation is similar to equal thickness cellulose insulation, with an R-value of 3.5 per inch (1). You can purchase denim insulation in batts of different thicknesses. You can easily install the batts between the studs. 

4. Fiberglass  

Surprising as it may seem, fiberglass insulation is a sustainable, eco-friendly insulation option. Fiberglass is, as the name suggests, glass spun into fibers. And glass comes from sand, an abundant natural and renewable resource.

Beyond that, much of the glass that is melted down to make fiberglass comes from recycled glass bottles – how green is that?

Lightweight and cost-effective, fiberglass is a common insulation choice for both new homes and retrofitting older construction. It has a 3.14 R-value per inch (2). It is available in blankets in either batts or rolls. You can also choose loose fill blown in. 

One concern people do have with fiberglass insulation is that manufacturers use formaldehyde in the manufacturing process. If you have respiratory problems and are looking for formaldehyde-free materials, you may want more natural insulation.

5. Icynene 

Icynene is a spray foam insulation. To install it, professionals will spray a thin layer of foam. It quickly expands to create a soft foam with an almost angel food cake consistency.

The tiny air pockets in the foam make it an effective insulator. It ensures there are no air leaks in your house.

While most Icynene products are petroleum-based, a new icynene product uses castor oil, giving you one more choice when looking at eco-friendly insulation options. 

6. Mineral Wool 

Spinning rocks into wool sounds like some backward fairytale, but that is precisely how they make mineral wool. They take natural minerals like basalt or industrial slag, heat it to molten temperatures, and spin it into fibers. The process is similar to making fiberglass. There are two types of mineral wool- rock wool and slag wool, depending on which material they used to make it. 

Mineral wool is sold in batts and installed similarly to fiberglass. It also has a comparable r-value at 3.14 per inch for rock wool (2).

7. Mycelium 

Mycelium is creating a lot of buzz in the green building world. 

Mycelium is made from the rootlike structures of mushrooms. It can be grown into different shapes and sizes. Currently, people are using forms to grow mycelium into bricks. While the bricks are not strong enough to add structural integrity to your home, they seem to be an excellent natural insulation option.

Mycelium is still in the experimental stages, so you can’t use these mushroom bricks in your home just yet. But keep an eye on this fascinating new material for the future. 

8. Polystyrene  

When thinking about green insulation options, polystyrene seems a little out of place. But this plastic-based insulator does such an excellent job at saving energy to help reduce your carbon footprint.

Available in rigid boards, polystyrene beadboard has an r-value of 4 per inch- meaning it is better than many of the other common insulators on our list (2). 

9. Sheep’s Wool  

You know how nice and toasty you feel wearing a warm sweater in the winter, even when it’s cold and damp? That’s because of the wonderful natural insulating properties of sheep’s wool. 

Wool insulation absorbs moisture and turns it into heat. It can also help filter out chemicals from the air, improving indoor air quality. So, if you are looking for natural, non-toxic insulation, sheep’s wool is a great choice. 

Check out this video to learn more about how sheep’s wool can keep your home warm:

10. Polyurethane Foam  

Polyurethane foam insulation is another material that seems a little strange on a list of green insulation options, but you would be surprised. Energy-efficient insulation does more than lower your energy bill; it also helps lower your carbon footprint.

Polyurethane foam is available either in rigid boards or as spray foam. It is particularly popular because it has an R-value of 6.25 when sprayed in place (2). 

Traditional manufactures have made polyurethane spray foam insulation from petroleum-based products. Soy-based polyurethane foam is available if you are looking for a more natural insulation option. 

This type of insulation can be sprayed in, just like traditional spray foam, but it is a more eco-friendly insulation option because it is plant-based. 

11. Straw Bale 

While straw bales may seem like a new type of alternative insulation, the truth is people have been building with straw bales since pioneering times. The R-value of straw bales varies depending on how tightly packed the straw is, but it ranges between 2.38-0.94 per inch. This value may seem low, but you have to realize that building with strawbale, you have larger than average walls (3). 

Straw bales work well for new construction but aren’t suitable for insulating foundations or locations with moisture problems. But you can use straw bales to insulate walls and attics. Heck! You can even build load-bearing walls with them. The critical thing to remember is that they must be well protected from moisture. You can use thick plasters or stuccos. 

Installation is easy. You stack one bale on top of the other. Make sure to anchor the straw bales well to the foundation and roof. If your walls aren’t load-bearing, fill the bales in between the studs. Straw bales are a great option if you are looking to work with green building materials. In many ways, they are just like any conventional home — you can install low-flow toilets and low-flow showerheads, no problem.

12. Rigid Cork  

Cork is one of our favorite green insulation materials. It comes from the outer bark of oak trees — harvesting does not harm the tree! So it is a sustainable and renewable material. 

Cork formed into rigid boards provides excellent thermal insulation and is also a very effective sound insulator. And it is one of the few recyclable insulators out there.