Green Investment Resources: Sustainable Insulation

Insulation is an integral part of building a new sustainable home or retrofitting an older home to be more sustainable. In fact, focusing on insulation is one of the most effective ways that homeowners or builders can retrofit a home with sustainable features.  Builders can switch out older insulation, containing potentially harmful materials, for new or recycled sustainable insulation, or even insulation made from natural materials. 

Sustainable insulation should have better insulating capacity, and should not contain harmful chemicals. Harmful chemicals in insulation can include formaldehyde-based binders, isocyanates, halogenated flame retardants, and organotin catalysts. Ideally, sustainable insulation should be made with at least party-recycled materials, and the insulation should be recyclable itself. Homeowners or builders might also consider where the sustainable insulation was made. Efforts to purchase locally-made insulation are more sustainable, as well. 

Sustainable insulation typically has a higher R-value, or ability to prevent heat flowing into or out of the home. Exterior walls should have R-13 to R-23, while ceilings and attic spaces can have anything from R-30 to R-49. Although sustainable insulation options could necessitate a large financial investment initially, they will heat the home well and ultimately reduce the cost of heating the home. 

There are several types of sustainable insulation on the market. A few of the most popular types of sustainable insulation are described below. 


Fiberglass usually contains at least 50% recycled material. Some types of fiberglass might have upwards of 70% recycled material. The sustainability of fiberglass insulation really relies on which brand and installation method is chosen. Some fiberglass options can contain formaldehyde, or have a lower R-value. The cost of fiberglass insulation is about $0.64 to $1.19 per square foot. 


Denim insulation is made from the scraps and clippings of denim manufacturing facilities. It has an R-value between R-13 and R-30, which indicates a good thermal rating. Denim insulation is 100% recyclable. A single roll of denim insulation costs about $6. 

Loose Fill Cellulose

Loose fill cellulose is made up of at least 75% recycled newspaper, as well as cotton. This is one of the oldest types of insulation. Its production methods are low-energy. Loose fill cellulose is usually easy to find locally. The cost of loose fill cellulose is about $1 to $1.50 per square foot. 

Rigid Cork

Rigid cork is made of 100% cork. This material comes from the outermost bark of oak trees that are at least 18 years old. Rigid cork insulation is 100% renewable and recyclable. Depending on the brand, rigid cork costs anywhere from $3.50 to $6.50 per square foot.