Comparing Eco-Friendly House Insulation Materials That Lower Utility Costs

A well-insulated structure plays a significant role in regulating your home’s overall energy efficiency and, as a result, its environmental impact. As homeowners become more conscious of sustainability and long-term savings, eco-friendly insulation materials are gaining popularity. 

Our guide covers how sustainable insulation performs better than synthetic options when it comes to breathability, toxicity, and embodied carbon, along with what you should look for when selecting the right material. 

We also compare six eco-friendly insulators for homes, including:

• Hemp Insulation

• Wood Fiber

• Cellulose

• Denim

• Cork

• Mineral Wool

Work with an experienced architect to navigate sustainable home design choices with ease. 

What Is Sustainable Insulation, and Why Use It?

Sustainable insulation relies on recycled or natural materials to help regulate a structure’s heating and cooling and reduce energy consumption. 

Compared to synthetic products like fiberglass or spray foam, green insulators have lower embodied carbon or are carbon-negative, which factors in the material’s carbon emissions associated with production, transportation, and disposal. This makes them an ideal choice for eco-conscious homeowners and builders who want to minimize environmental harm.

Sustainable insulators perform just as effectively in thermal regulation as conventional options when installed correctly. They also have added advantages such as breathability and lower levels of emitted toxins, both of which help improve indoor air quality. 

Finally, homeowners retrofitting their residences can earn tax credits for installing sustainable insulation as part of the Energy-Efficient Home Improvement Credits (25C). You could receive 30% back on eligible upgrades, including up to $1,200 on improved insulation, air sealing, and weatherization.

What to Consider When Choosing an Eco-Friendly Insulator

When selecting eco-friendly house insulation options, you should define your sustainability goals. Is it more important to invest in recycled materials and products with lower embodied carbon? Or do you prioritize energy efficiency to lower your home’s operational energy consumption throughout its lifetime?

We balance these factors:

• Sustainability Certifications: Look for GREENGUARD Gold and LEED labels that indicate the insulation has been thoroughly tested according to rigorous environmental and health standards.

• R-Value Rating: This measures thermal resistance, which is an insulator’s resistance to heat flow. Higher R-values per inch mean better insulation performance. Eco-friendly insulators perform comparably to fiberglass but often have a lower R-value than synthetic options like spray foam and expanded polystyrene.

• Durability and Longevity: Long-lasting materials reduce the need for replacement and may require less maintenance throughout their lifespan. Look for sustainable insulators that are fire, moisture, and pest-resistant.

• Health and Indoor Air Quality: Many synthetic insulators give off volatile organic compounds (VOCs), which are chemicals that can be harmful when inhaled. Choose low-VOC, non-toxic insulators to avoid off-gassing and allergens.

• Cost: Some green insulators have higher up-front costs than conventional options. While this may change as the market shifts toward sustainable building materials, it’s still important to balance up-front costs with long-term energy savings and durability.

If you’re working with a residential architect, they can advise on your goals and identify the right insulator for your home and location.

The 6 Best Environmentally Friendly Insulators for Homes

1. Hemp Insulation (Hemp Batts)

Hemp batts, wool, and other hemp insulators are some of the leading eco-friendly insulation options in modern green architecture. These insulators consist of treated hemp fibers formed into semi-rigid panels. Hemp is a fast-growing crop that is non-toxic, versatile, and easy to recycle. Because hemp stores carbon dioxide throughout its life span, it acts as a carbon sink and is considered carbon-negative.

We prefer using hemp batts for our residential clients because they perform well across key insulation metrics while having added benefits over synthetic options. However, other hemp insulators, such as hempcrete or hemp lime, are also gaining popularity.

With an R-value of about R-3.5 to R-3.7 per inch, hemp batts are thermally resistant with excellent thermal mass. They’re breathable, allowing moisture to escape without compromising the home’s temperature. This also makes hemp insulation mold and mildew-resistant.

Pros: 

• One of the most carbon-negative insulators

• Breathable, naturally helps regulate home temperature and moisture

• Strong sound-dampening properties

• Fireproof

• Non-toxic

• Reusable and biodegradable

• Hemp has a 3–4 month growth cycle, making it faster to renew than softwood, which takes up to 25 years

• Low-density material that’s resistant to cracking from movement, making it a top insulator for areas with earthquakes

Cons: 

• Not as widely available in the U.S.

• More expensive than synthetic insulation

2. Wood Fiber Insulation

Wood fiber insulation is made from leftover wood chips and sawmill waste from forest management and lumber mills. By repurposing lumber byproducts into rigid or semi-rigid composite boards, wood fiber insulation helps reduce waste and is highly renewable. The boards also store significant amounts of CO2, holding a net negative carbon footprint.

Given its comparable benefits to hempcrete and wider availability, we often turn to wood fiber as an environmentally friendly insulation option when building sustainable homes.

In terms of performance, the R-value for wood fiber insulation varies between R-3.6 to R-4.2 per inch. The boards are treated with borate or ammonium phosphate to be fire-resistant and paraffin wax to be moisture-resistant.

Pros:

• Excellent moisture regulation

• Breathable

• Negative carbon footprint

• Easy to install

• Good acoustic performance

Cons:

• Heavier than other materials

• May require a weatherproofing layer

3. Cellulose Insulation

One of the most common green insulators, cellulose insulation is made from recycled newspaper, boxes, and other waste paper. Homeowners gravitate toward cellulose insulation because it’s cost-effective and widely available.

There are three main types of cellulose insulation:

• Loose-Fill (Blown-In) Cellulose: Shredded cellulose blown onto open spaces like exposed attic floors or in closed wall cavities with a specialized machine. Dense-pack cellulose is a compacted version of loose-fill, which is used in wall cavities to prevent settling. This method is best for retrofits.

• Wet-Spray Cellulose: Water mixed in with cellulose forms a thick, clumpy mixture, allowing the insulation to be blown onto open walls like spray foam alternatives. It’s best used for new construction.

• Stabilized Cellulose: Water and an adhesive combine with cellulose to create an eco-friendly insulator that maintains its shape and density. It’s a preferred choice for sloped spaces.

Most cellulose insulation is treated with borate or ammonium phosphate to be fire and pest-resistant. The average R-value falls between R-3.2 to R-3.8 per inch, depending on the product density.

Cellulose Insulation Pros:

• 85% recycled content

• Good air sealing when blown in

• Affordable

• Versatile material to meet most residential home needs

Cellulose Insulation Cons:

• Can settle over time

• Sensitive to moisture if not protected

4. Denim Insulation (Cotton)

Denim insulation, or cotton insulation, is primarily made of about 85% recycled jeans and other cotton fabric waste. Like fiberglass, denim insulation comes in two forms: loose fill for exposed attic floors and denser batts that can be rolled out and cut to spec. It’s a soft material that doesn’t spread irritants when disturbed, meaning you won’t have issues if you accidentally touch it with your bare skin.

Denim insulation is still relatively new, so it can be harder to find than other sustainable insulation options. However, it’s growing in popularity thanks to its excellent performance in sound dampening, breathability, and ease of use. A denim batt has an average R-value of R-3.5 per inch and is treated to be flame-resistant.

Pros:

• Non-toxic

• Easy to install

• Good soundproofing

• Made from post-consumer waste

Cons:

• More expensive than fiberglass

• Can absorb moisture without added treatment

• Not as widely available as other sustainable insulation materials

5. Cork Insulation

When it comes to environmentally-friendly insulation materials, it’s hard to beat cork, which comes from the bark of the cork oak tree. The bark is a rapidly renewable resource that can be harvested sustainably without harming the tree or through upcycling cork granules from the stopper industry. Both options leave forests intact and minimize environmental destruction. 

Cork insulation is produced by steaming and pressing cork granules into semi-rigid boards. The material is naturally fire, moisture, and mold resistant, so it doesn’t require any additive chemical treatments. With an R-value of R-3.6 to R-4.2 per inch, cork boards perform comparably to synthetic foam boards.

Following high success in European markets, cork insulation has started to gain popularity in the U.S. However, it can still be harder to find compared to other sustainable insulators, which makes it more expensive.

Pros:

• Naturally moisture and pest-resistant

• Excellent sound dampening

• Long-lasting and reusable

• Created with sustainable harvesting methods

Cons:

• High cost

• Limited availability in North America

• Heavier than foam boards

6. Mineral Wool Insulation (Rock Wool)

Mineral wool, also known as rock wool, is a type of high-temperature insulation made from spinning molten minerals such as basalt rock, stone, ceramic, silica, and even iron ore waste in a furnace to form intertwined wires. These wires are shaped into batts, boards, or loose wool to suit different projects.

Homeowners gravitate toward mineral wool thanks to its versatility and exceptional performance. Mineral wool is incombustible, excels at noise absorption, and retains its insulation properties if wet. As an inorganic product, it is resistant to mold and mildew. Its R-value is R-4.0 to R-4.2 per inch.

Is Mineral Wool Environmentally Friendly?

While architects initially praised mineral wool as a natural insulation material, more professionals are questioning its green reputation. Mineral wool requires extensive energy and water to produce, which contributes to high carbon emissions. To heat the raw materials, manufacturing sites burn coal and fuel daily—a process that also releases VOCs into the air. Not to mention, it is energy-intensive to transport and source the raw materials in the first place.

We typically limit the use of mineral wool insulation in our projects, but it is useful in certain cases such as fire-rated wall assemblies. In these scenarios, we will specify it to meet our clients’ goals.

Pros:

• Excellent fire and moisture resistance

• Won’t sag or settle over time

• Mold and mildew-resistant

• Non-toxic

Cons:

• Energy and water-intensive to produce

• Isn’t biodegradable

• Some mineral wool irritates bare skin

Are Environmentally Friendly Insulators Worth It?

The most environmentally friendly insulation depends on your home's design, location, and goals. If carbon sequestration and low environmental impact are a top priority, hempcrete and wood fiber stand out. For affordability and recycled content, cellulose and denim are great choices. Mineral wool balances performance, availability, and durability, but we limit its use to specific scenarios.

Ultimately, the best sustainable insulation is the one that fits your home's needs and helps you reduce energy consumption and carbon emissions.

Ready to build a more energy-efficient, eco-conscious home? Connect with our experts at Trade Design Build to explore our portfolio of sustainable projects and find a solution for your home.