A homeowner appliying Rockwool insulation batts on a wall, a form of green insulation

Green insulation reduces your carbon footprint without sacrificing insulation value. There are numerous eco-friendly options at your disposal. However, some are cheaper and more readily available, whereas others are expensive and extremely efficient. It’s up to you to decide which green insulation is worth it for your home.

This post will cover all the types of green insulation you can look through, listed in order from the best R-value to the lowest.

So let’s get into it!

Which Types of Green Insulation Are Best?

The best types of green insulation include aerogel, cork, mineral wool, icynene, sheep’s wool, denim, cellulose, mycelium, and fiberglass. These environmentally-friendly materials have R-values between 2.7 and 10.3 per inch. In addition, some of them are blown-in, whereas others are sealed with adhesives.

Now that you’ve seen the rundown let’s investigate each of these varieties in greater detail.


Aerogel is one of the newest forms of green insulation. It uses a unique process that starts with removing most of the silica from silica gel, leaving it primarily composed of air. 

Most insulation works best with air pockets, which is why aerogel is so effective. This insulation has a sky-high R-value of 10.3 per inch.

Although it’s made of synthetic materials, aerogel is highly eco-friendly. This green insulation doesn’t require a lot of energy to produce, and it lasts several decades. So your home will stay insulated from various fluctuating temperatures throughout the year.


  • Aerogel has the highest R-value, almost double that of second place.
  • It’s mostly made of air, which means it’s incredibly lightweight.
  • Aerogel doesn’t grow mold and mildew as easily as most other forms of insulation.


  • Aerogel is one of the most expensive ways to insulate a home.
  • It’s not as readily available as other forms of insulation (though many companies are working to fix this issue).


Pure cork is one of the most effective ways to insulate a home. Not only does it limit temperature fluctuations, but it can also prevent sound from coming through the walls. 

A closeup on the end of a semi-unrolled roll of corkboard, an eco-friendly ceiling material

Buildings claims cork has a maximum R-value of 4.2 per inch, meaning it’s the second-highest R-value you’ll come across for high-quality green insulation.

Cork insulation requires minimal production. Manufacturers have to cut it into sheets, but it’s naturally energy-efficient and insulated.


  • Cork is sustainable, easy to produce, and readily available.
  • It’s effortless to install cork throughout your home.
  • Cork insulation isn’t nearly as messy as fiberglass, spray foam insulation, or batts.


  • Cork isn’t the best insulation for those living in humid climates.
  • It’s susceptible to mold and mildew if there’s no vapor barrier.
  • Cork insulation swells if it gets too hot or wet.

Mineral Wool

Mineral wool (Rockwool) has a 4.0 R-value per inch. As a result, it’s one of the most popular forms of insulation (even for those who don’t care about being eco-friendly). 

It uses a lengthy process of melting minerals and spinning them into fibrous insulation sheets. However, it doesn’t take a lot of energy. 

Close-up of worker hands in white gloves installing mineral wool insulation staff in wooden frame for future walls for cold barrier.

Furthermore, mineral wool is readily available since it can be made of several different rocks and minerals. Unfortunately, mineral wool insulation is slightly more expensive than fiberglass and other low-cost materials.


  • This eco-friendly insulation is easy to find and reliably durable.
  • It’s sustainable and can be created for the foreseeable future.
  • Rockwool has a higher R-value than most eco-friendly materials.


  • Mineral wool can be a bit costly for those shopping on a budget.
  • It’s itchy and uncomfortable to install (protective goggles, sleeves, and masks are required).


Icynene has an R-value of 3.7, but that’s not the only reason it is on our list. It’s also designed to prevent mold, mildew, and bacterial growth. 

How Stuff Works claims icynene can expend over 100 times its original size. Therefore, hiring a professional to handle the job is best since a minor misstep can cause bulging walls and uneven insulation.

Another reason so many people love insulating with icynene is that it’s lightweight and full of air. These air pockets are the main reason it prevents hot and cold air from leaving your home.


  • Icynene uses a safe formula that’s not harmful to people or pets.
  • It’s very lightweight and expands without effort.
  • It’s a perfect solution for people living in wet, humid climates.


  • Icynene is one of the messiest insulation materials to install.
  • It can sag if too much of it is added, which reduces its ability to control cold fronts.

Sheep’s Wool

Sheep’s wool has been used as insulation for many years. It’s slightly more expensive than synthetic insulation materials but has a higher R-value of 3.6. Furthermore, sheep’s wool naturally provides excellent sound insulation.

Sheep's wool closeup. The wool has been sheared from the sheep and is light brown and white in color. The wool can be used to insulate interior walls.

If you use sheep’s wool to insulate your home, it’s best to choose materials treated with borax (or similar solutions) to prevent bugs from making a home out of it.


  • Sheep’s wool is readily available, easy to install, and safe.
  • You don’t need to wear protective clothing or gear when installing it.
  • It’s one of the most sustainable green insulation materials available.


  • Untreated sheep’s wool insulation can harbor bugs.
  • It’s much more expensive than synthetic insulation.


Denim might not be as popular as fiberglass, cellulose, and a few other green insulation materials on the list, but it’s incredibly effective. This insulation has a 3.5 R-value, making it the middleman regarding budget, insulation, and availability.

Companies produce denim insulation by removing buttons, zippers, and other parts. Then, the denim is shredded and coated in borax, then matted together in batts. Some denim insulation is blown-in, though.

A half batt of denim insulation on the floor in front of the wall it is installed in


  • Denim is readily available and made of recycled materials.
  • It’s growing in popularity due to its sustainability and energy efficiency.
  • It can be produced in multiple insulation forms.


  • Denim insulation is more expensive than fiberglass insulation.
  • Denim insulation batts can be challenging to cut and shape.


Popular Mechanics explains that cellulose is likely the most popular form of recycled insulation. It’s typically made of shredded newspapers and other materials. The vast majority of cellulose insulation is blown-in, making it one of the quickest insulation materials to install.

Cellulose has a 3.5 R-value. It’s very similar to denim in that it’s made of recycled materials, has a middle-ground insulation value, and is easy to find at almost any hardware store. It’s also available in many sizes to accommodate most houses.

A pair of cupped hands holding cellulose of the type that is often used to insulate interior walls.
Cellulose is an eco-friendly material that can be used to insulate interior walls.


  • Blowing cellulose is extremely quick and effective.
  • It’s pretty affordable compared to other green insulation materials.
  • You can find cellulose insulation almost anywhere online or in person.


  • Cellulose settles, meaning it needs to be topped off a few years after the installation.
  • It’s one of the messiest green insulation materials because it’s dusty.


Mycelium has an insulation value of 3.0 per inch. According to Eco Peanut, it’s exceptionally fire-resistant. It’s made out of the same material mushrooms produce when growing. Mycelium is typically made into sheets or bricks. However, getting your hands on this form of green insulation is tough.

On the bright side, it’s built for longevity, natural resistance to the elements, and eco-friendly insulation. Mycelium is becoming more popular, which inevitably means it’ll be more widely produced down the road.


  • Mycelium is quite resistant to fire damage compared to other green insulation materials.
  • It’s made out of mushroom root structures, so it’s as natural as it gets.
  • It has a balanced carbon output, so you won’t increase your carbon footprint.


  • Mycelium is currently very difficult to find because it’s not widely produced.
  • It’s not as insulative as many other forms of eco-friendly insulation.


Fiberglass often doesn’t come to mind when people refer to eco-friendly insulation. However, it’s prevalent because it’s one of the cheapest and most readily available insulation materials. In addition, fiberglass insulation has several benefits, including its 2.7 R-value and the fact that it’s mostly made of recycled glass.

Fiberglass insulation being installed in the underside of a home attic ceiling, showing a beige fiberglass batt

This green insulation material comes in batts, but you can also blow it in. However, it’s notorious for itchiness, so wear protective gear. Furthermore, you’ll have to seal the cracks to ensure none of the insulation makes its way into the living spaces of your home.

For more information regarding this material, review our fiberglass pros and cons list.


  • Readily available at almost any hardware store.
  • It’s as affordable as it gets for eco-friendly insulation.
  • This material is mainly made of recycled products, reducing carbon emissions and landfill congestion.


  • Fiberglass is itchy and can be quite dangerous to install without protective gear.
  • It’s not as insulating as most other green insulation materials.

Final Thoughts

Whether you choose aerogel or fiberglass, you will find green-friendly insulation that works for your house. 

Set your budget, decide if you want it professionally installed, and determine which R-value you need per inch. Remember that most insulation is sold between one to ten inches thick, so you’ll likely get much more than the base R-values listed above.


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