Pros and Cons of Organic Insulation Materials

If you’re chemically sensitive, or just “organic” minded, and building or renovating your home, here’s a primer on these eco friendly insulation options.

Materials such as cotton, hemp and wool insulation have gained popularity in recent years, particularly as interest in green building grows. In the past, obtaining these insulation products, not to mention finding laborers to install them, impeded their acceptance by builders. But times are changing. For example, it’s now possible to order Hemp Batts online directly, and insulation crews are becoming more familiar with the material.

Note also that, as with many products, an organic label does not guarantee that every aspect of a product is “green.” Details matter. For example, cotton insulation made from 80 percent recycled denim scrap such as that offered by Bonded Logic Inc is one that I would consider green insulation. 

They are one of the very few companies currently offering this type of product. According to Cotton Incorporated, it takes about 670 liters of water to produce one kilogram of cotton, equivalent to a single t-shirt and pair of jeans, so the recycled aspect is essential.

Although it looks little different from more mainstream types of insulation, this home was insulated with Havelock’s wool insulation.

Organic Insulation: Sheep to the Rescue?

Wool insulation is another product that’s often overlooked, that should be part of the natural insulation discussion. A little-known aspect of the wool industry is that many sheep farmers switched from wool production to raising livestock for the meat industry. 

As a result, in places such as Ireland, wool is now treated as waste material, sold at very low cost. Unfortunately, that shift in “value” doesn’t seem to have reached the U.S. yet. Wool here is still relatively dear.

The Pandemic gave a boost to wool insulation sales in the U.S., perhaps because of new attention to indoor air quality and health. Havelock Wool's sales, for example, quadrupled during the first year of COVID-19 and grew another 25% in 2021.

Wool insulation here tends to be about 25% to 50% more expensive than its fiberglass alternative, but advocates and resellers say that it’s a viable and effective “clean air” insulation. They suggest that wool’s ability to absorb common chemicals and pollutants, such as formaldehyde, means wool insulation can actually improve air quality (source).

Havelock wool insulation takes advantage of wool’s natural ability to absorb toxins and keep mammals warm.

Hemp In Building Materials

Hemp has been around forever. But it only now seems to be making real headway in the building industry as an environmentally friendly product. Part of the reason again: the Covid-19 Pandemic.  People are still reeling from building material sticker shock, as prices suddenly doubled and tripled on some basic building products.

Don’t confuse the type of hemp used in building materials with marijuana, however. You won’t get high by burning your hemp insulation. That’s not to say the exponential rise of legalized pot hasn’t raised awareness of hemp. The total  increase in production of “industrial hemp” worldwide has been dramatic. 

Another big factor in Hemp’s reputation boost is its recent acceptance into the International Residential Code. One form of hemp called Hempcrete, a carbon-sequestering fibrous insulation material made from hemp stalks and lime, has been approved for the 2024 code, set to be published formally in 2023. 

It will feature Hemp-Lime (Hempcrete) under “Appendix BA.” Specifically, hempcrete was approved as a non-structural wall infill system similar to cob and straw bale construction.

The Department of Energy (DOE) considers hemp game-changing, and has put money into helping some companies research and innovate. Hemp insulation looks a lot like other types of batts, and has similar insulating properties.

HempWool, for example, has an R-value of about R-3.7 per inch, about equal to fiberglass batts. Mattie Mead, Hempitecture’s CEO and co-founder, told Hemp Benchmarks “we use a little less than a pound of fiber in a square foot of R-13 HempWool; a mere fraction of an acre.” She added that “fiber hemp should yield four to five tons per acre, once genetics and cultivation practices are optimized for the U.S.’s various growing regions.”

Pushback from builders and code officials toward hemp and other organic insulators might be related to fire risk, but HempWool does have a Class C fire rating. Some companies are testing flame retardant additives to bring hemp insulation up to Class A level, but are rightly concerned about damaging their reputation as a toxin-free alternative.

Ekolution’s hemp batts have low embodied energy and no toxins or VOCs.

Don’t Be Too Hard on Cellulose

I like the health aspects of “natural” materials, but I also think cellulose deserves consideration in all but the most narrow definitions of “natural” insulation. Cellulose insulation is technically derived from plant fibers (typically recycled paper), but it is not considered an organic material in the same sense as cotton or hemp or wool. 

Nonetheless, it hits a lot of the eco-friendly buttons. The product is: 

• Low in embodied energy. 
• Insect and fire resistant..
• Pretty easy to install, even for a DIY homeowner. 
• Widely available and affordable too.

How to Choose the Right Organic Insulation

The choice of an organic insulation comes down to your family. Do you have an asthmatic child or elderly person with respiratory issues at home? If so, the extra cost may be warranted. An argument might also be made that no formaldehyde is good formaldehyde in your home, and you’re protecting your future self by building without trace toxins in your walls.

You may also pay a premium to an installation contractor who’s not familiar with these products. My advice is to find a contractor who’s actually familiar or excited about trying one of these product lines in your home.

Publisher’s Note: This content is made possible by our Today’s Homeowner Campaign Sponsors: Whirlpool, Carrier and Jinko Solar. These companies take sustainability seriously, in both their products and their operations. Learn more about building and buying homes that are more affordable and less resource intensive.