7 Eco-Friendly Insulation Alternatives

Insulation manufacturers are producing more environmentally friendly products because consumers are demanding them. Insulation is called green because it uses renewable resources. Or saves energy when manufactured. To be viable, it also must provide good insulation R-value for the money invested.

Eco-Friendly Insulation

What Makes Insulation Eco-Friendly?

To be classed as environmentally friendly, insulation products should meet four important criteria.

  • Safe. Non-hazardous to the people manufacturing it, installing it, or living with it.
  • Sustainable. Raw materials should be renewable or recycled.
  • Recyclable. Can be reused, recycled, or composted at the end of its life.
  • Low Energy. Low embodied energy use when manufactured. For instance, manufacturing fiberglass requires 10 times more energy to produce than cellulose.

Benefits of Eco-Friendly Insulation

In addition to leaving a smaller carbon footprint and providing good to very good R-values, sustainable insulation benefits include:

  • Fire retardant.
  • Negligible off-gassing of toxic chemicals.
  • Safe to handle without special equipment.
  • Zero landfill use–usually.
  • Minimal chance of health risks over its lifespan.
  • Good to very good soundproofing.

7 Green Insulation Options

Eco-friendly insulation is used in most of the same locations as traditional insulation–walls, roofs, attics, and floors. Not every product is suitable for every application. All of them can be used for new construction or renovations that completely gut the building. Some cannot be used for retrofits.

1. Sheep Wool Insulation

Compressed sheep wool insulation batts contain innumerable dead air pockets. Making it an excellent insulator. It may be the most natural insulation available. Sheep wool is a natural fire retardant but is not insect-resistant.


  • R-3.6 per inch.
  • Easy to install batts.
  • Safe.
  • Natural fire retardant.


  • Must be treated to repel insects–usually with boric acid which also acts as a fire retardant.
  • Costly.
  • Lack of availability.

2. Cellulose Insulation

Cellulose insulation is manufactured from up to 85% recycled paper and cardboard. It is the most used and versatile recycled insulation. The small particles fill cracks and gaps and easily flow around obstructions like pipes and wiring.


  • Approximately R-3.5 per inch.
  • Versatile. Can be blown wet or dry into wall stud cavities–new construction or retrofit. Loose-fill blown into attics.
  • Available in batt form but not popular.
  • DIY or contractor installed.
  • Relatively inexpensive.
  • Boric acid is added as fire retardant and as pest control.
  • Dense. Blocks air leaks.


  • Dusty when installed.

3. Denim Insulation

Denim insulation is made from recycled blue jeans, cotton clothing, and remnants. Almost all of the inputs are recycled. Boric acid is added as a fire retardant and pest inhibitor. Available in wall batts and as loose fill to blow into attics. Growing and manufacturing cotton has a huge carbon footprint. Recycling helps make up some of it.


  • R-3.5 per inch.
  • Fire retardant.
  • Insect resistant.


  • Expensive.
  • Difficult to make exact cuts.
  • Not always readily available.

4. Cork Insulation

Cork insulation has an R-value of up to R-4.0 per inch. It is available in semi-rigid sheets of various thicknesses. Cork insulation is made from the waste of wine cork manufacturers. The raw material is from the bark of cork oak trees. The bark regenerates every 10 years.


  • R-value up to R-4.2.
  • Easy to install.
  • Readily available.
  • No extra chemicals.
  • Excellent acoustic properties.


  • Not available as batts or loose-fill.
  • Can swell in hot or humid areas.
  • Susceptible to mold and mildew growth.

5. Icynene Insulation

Icynene insulation is a spray foam made from castor oil. It expands up to 100 times its size. It fills all gaps and cavities and molds itself around obstructions like electric boxes and pipes. Icynene does not support mold growth and it is not a food source for insects or rodents.


  • Up to R-3.7.
  • R-value does not degrade.
  • Seals all air leaks.
  • Excellent product for wet humid climates.
  • Very good soundproofing qualities.


  • House may seal tight enough to require an HVAC system.
  • More expensive than conventional spray foams.
  • Not a DIY project. No kits available.

6. Aerogel Insulation

Aerogel insulation is manufactured by replacing the moisture in silica with over 90% air. It has the best R-value of almost any insulation and is the priceiest. The production process is very energy efficient. Available in sheets or as sticky material.


  • R-value of R-10.3 per inch.
  • Mold and mildew resistant.
  • Almost as light as air.
  • Will not degrade over decades of use.
  • Can be removed and reused.


  • Extremely expensive.
  • Only available in sheets or stickers.
  • Not readily available.

7. Hemp Insulation

Hemp insulation is made almost entirely from hemp plants. Available in batt form. Can be installed anywhere traditional batts are used. Hemp insulation has an R-value of R-3.5 per inch. It is one of the few products that does not lose R-value when compressed.


  • R-3.5 per inch.
  • Compressible without losing R-value.
  • Naturally pest repellant.
  • Easy to Install without special PPE.


  • Requires a vapor barrier in humid locations.
  • Restricted availability due to government regulations.
  • Fairly expensive.

More Eco-Friendly Insulations

The demand for alternative insulation materials continues to grow. Some of the following products have reached the market but to date have limited distribution.

  • Mycelium Insulation. R-3.0. Sheets and bricks are manufactured by allowing mushroom-type fungus to grow into wood chips and sawdust. Almost impossible to find.
  • Wood Fiber Insulation. Developed in Germany. Widely used in Europe and Britain. Available in batt form or boards.
  • Plastic Insulation Batts. Made from recycled plastic bottles. Growing popularity in the European Union and Britain but very difficult to find in North America.
  • Glass Wool Insulation. Uses up to 80% recycled glass. Available in North America, Europe, and Britain but not common. Not the same product as fiberglass.