Sustainable Insulation for a Healthier Home
Discover the best eco-friendly insulation options for a healthier, more sustainable home
By Bec Gregory
Insulating your home is about more than just energy efficiency—it’s about your health, your home’s longevity, and the environment. The wrong choice can lead to mould, harmful chemical exposure, dry rot, and even pest infestations!
Investing in sustainable insulation now means fewer problems down the road— for your home, health and the planet. But with so much conflicting information online, choosing the best sustainable insulation for your home can feel overwhelming. Worse still, few discussions address the potential health risks of different insulation materials.
Plus, if you’ve ever felt pressured to follow the advice of a pushy salesperson or an old-school contractor set in their ways, you’re not alone!
So what’s the most sustainable insulation for your home?
Let’s start with a word (of warning) about spray foam insulation!
Spray Foam Insulation Pros and Cons
Spray foam insulation is made from liquid polyurethane that sets upon application. It creates a solid, insulating layer. It’s very easy to use, and you can trim it and paint it according to your tastes, once it’s set.
While it’s often praised for being the most energy-efficient insulation due to its high R-value (a measure of insulating effectiveness), its environmental footprint tells a different story.
A quick look on Amazon warns the following about spray foam insulation:
Danger!
- Causes serious eye irritation.
- Causes skin irritation.
- Extremely flammable aerosol.
- Harmful to aquatic life with long lasting effects.
- May cause allergy or asthma symptoms or breathing difficulties if inhaled.
- May cause an allergic skin reaction.
- May cause damage to organs through prolonged or repeated exposure.
- May cause harm to breast-fed children.
- May cause respiratory irritation.
- Pressurised container: May burst if heated.
- Suspected of causing cancer.
Yikes!
Ineed, spray foam insulation can release harmful chemicals, such as isocyanates and volatile organic compounds (VOCs). This is true during and after installation, too. These chemicals have been linked to respiratory issues, skin irritation, and long-term health risks, as highlighted by the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA).
Um, a hard pass, then!
So, what sustainable insulation materials are available then? Read on to find out!
Main image by Rockwool
The Best Sustainable Insulation Materials for Your Home
Plant Based Materials
1. Mineral Wool (Rockwool or Thermafiber)
Mineral wool is fire-resistant, breathable, and durable. It also deters rodents and is an excellent sound insulator.
However, some brands use formaldehyde-based binders, so always choose formaldehyde-free options. Additionally, the manufacturing process is highly energy-intensive, and the material itself is not biodegradable.
One of the best sustainable insulation materials for: Soundproofing and fire resistance, particularly in walls, ceilings, and attics.
Available as: Batts, rolls, and rigid boards.
2. Wood Fibre Insulation
Made from renewable wood sources, it offers excellent moisture resistance and breathability. It is free from harmful VOCs and suitable for both walls and attics.
Wood fibre insulation contains some chemical fire retardants and is a relatively new product, meaning availability and contractor experience may be limited.
One of the best sustainable insulation materials for: Breathability and moisture control in walls and roofs, particularly in timber-framed buildings.
Available as: Rigid boards and loose-fill.
3. Hemp Wool Insulation
Hemp wool insulation is a carbon-negative, breathable material with excellent thermal performance. It retains its insulating properties even when damp, making it ideal for humid climates, and naturally repels pests!
It contains a small percentage of polyester binders and newer fire-retardant additives. On top of that, while durable, it is less widely available than conventional insulation, potentially increasing costs and installation challenges.
One of the best sustainable insulation materials for: Walls, roofs, and floors in humid or high-moisture areas.
Available as: Batts and rolls.
4. Straw Insulation
Straw insulation is fully biodegradable, carbon-sequestering, and naturally flame-resistant due to its silica content. But it’s labour-intensive to install, requires thick walls for optimal performance, and availability varies by location.
One of the best sustainable insulation materials for: High-performance insulation in thick walls. Those on a budget.
Available as: Compressed straw bales or pre-fabricated panels.
Image below: IndiTherm Flexible Hemp Batts. Image by Eco Merchant.
Recycled Materials
1. Cellulose Insulation
Made from recycled paper (primarily newspapers), cellulose insulation is an affordable, effective, and widely available option. It efficiently fills wall cavities, but it can settle over time, creating air gaps.
Additionally, it contains boric acid and other fire-retardant chemicals. These help resist pests and mould. Boric acid is non toxic when stable, but it may raise concerns for those seeking fully natural alternatives.
Some formulations may also contain plastic fragments, impacting their overall sustainability. Despite these drawbacks, studies highlight cellulose as one of the most eco-friendly insulation options due to its low embodied carbon and reliance on post-consumer materials.
One of the best sustainable insulation materials for: Filling wall cavities and attic spaces for high thermal performance at a lower cost.
Available as: Loose-fill and dense-packed spray insulation.
2. Recycled Glass Insulation (Glavel)
Manufactured from 100% recycled glass, Glavel is non-toxic, pest-resistant, fire-resistant, and highly durable. It’s a great option for basements and crawl spaces. But it’s gonna cost you a pretty penny! It’s extremely expensive compared to conventional materials.
However, while the upfront costs may be higher, the long-term benefits and potential savings in labour and materials due to its lightweight nature and ease of installation can help offset the initial investment.
One of the best sustainable insulation materials for: Insulating foundations, basements, and under concrete slabs.
Available as: Lightweight aggregate (foam glass gravel).
3. Recycled Cotton Insulation
The cotton in this insulation comes from the collection, recycling and recovery of textiles at “end of life”, largely denim. For example, Soprema Pavatextil P – Recycled Denim Insulation is comprised of about 85% cotton fibres – sourced mainly from jeans and a little bit of velvet – blended with 15% polyester fibres for added stability.
One of its key benefits is excellent sound insulation. Its dense fibres absorb sound waves, while its elasticity and porous structure dampen vibrations, reducing noise transmission between rooms and floors. It’s efficiency and eco friendliness mean it could even increase the resale value of your home.
One of the best sustainable insulation materials for: Soundproofing walls, ceilings, and floors.
Available as: Batts and rolls.
4. Sheep’s Wool Insulation
Sheep’s wool insulation is made from the waste of wool that cannot be used in the textile industry. It is naturally fire-resistant, regulates humidity well, preventing mould and mildew, and absorbs pollutants from the air, improving indoor air quality.
It is ideal for extreme weather conditions (think of how sheep survive in freezing mountains and scorching plains). But it can be costly, may have an odour, and is attractive to moths and rodents if not properly treated. Also, it could be an irritant to people with sensitivities to wool.
One of the best sustainable insulation materials for: Regulating humidity and improving indoor air quality in walls, ceilings, and lofts. Ideal for extreme climates.
Available as: Batts, rolls, and loose-fill.
Cost Considerations for Sustainable Insulation
While certain insulation materials are budget-friendly (such as cellulose), others can be quite expensive (like recycled glass insulation).
Shipping costs are also a major factor to consider—insulation materials are bulky and expensive to transport. The availability of sustainable insulation in your region can significantly affect its price.
Installation costs can also vary depending on the experience of the contractor you hire. Getting multiple quotes for different insulation options will give you a better idea of the real cost difference.
In Short…
Ultimately, the best sustainable insulation choice depends on your budget, climate, and personal priorities.
If affordability is key, cellulose is the best option. If you want a fully natural, non-toxic home, wool or hemp may be the way to go. And if you’re prioritising breathability and durability, mineral wool or wood fibre are solid choices. We don’t know of any eco friendly, non toxic forms of spray foam insulation, but if you do, let us know in the comments, below.
Stay warm. And stay healthy!
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