Which Type of Insulation is the Most Environmentally Friendly?

There are many different insulation products on the market however they all aim to achieve the same goal, and that is to increase the energy efficiency of the home by keeping warm air in during winter and keeping the warm air out during summer.

The US Department of Energy estimates that 43% of all energy consumption within the home is allocated to heating. By making your home more energy-efficient you will not only save money on utility bills but also reduce greenhouse gas emissions that are associated with maintaining a comfortable temperature within your home. 

That’s great news for environmentalists and tree huggers, but if you want to go the extra mile you can also choose an insulation material that is eco-friendly.

Which insulation material should you choose if you want to go green?

When it comes to interior insulation projects, you may be wondering – what type of insulation is the most environmentally friendly? There are two contenders for the top spot when it comes to insulating your home and staying green. These are cellulose insulation and spray foam insulation.


Cellulose has widely been praised as being one of the most environmentally friendly insulation materials on the market. That’s because it’s composed of up to 85% recycled newspaper. You can make yesterday’s news into today’s energy savings. The remaining composition of around 15% includes chemicals that are intended to make the newsprint fibers more resistant to fire and insect infestations, while also keeping it safe for household use.

The R-value of cellulose is similar to that of fiberglass at 3.5 per inch, however, it is more friendly for the environment because it is made of a higher percentage of recycled materials.  We’ll get to some of the nitty-gritty around why fiberglass is such a poor choice later.

Cellulose can generally be bought as a loose-fill product that requires special equipment for installation. This technique is known widely as blown-in insulation, which can also come in fiberglass and rock wool applications. The specialized machinery is used to blow the insulation material onto the floor of an open attic or into the space between existing walls. 

Cellulose is often a popular choice because of its high percentage of recycled material, and because it is relatively cheap and widely available. It does, however, have its share of disadvantages. 

Cellulose insulation can settle over time leading to decreased efficiency as an insulator. It typically only has a lifespan of around 20 years.  And while cellulose is treated with special chemicals to repel fire and insects, those treatments may not always be entirely effective.  It can also be a nuisance in damp climates because if it is exposed to any moisture it can become vulnerable to mold and mildew.

Spray Foam

As well as being the most effective type of insulation available, recent developments in technology have made spray foam one of the most eco-friendly! Due to the R-value reaching as high as 6.5 per inch spray foam is environmentally friendly simply due to the fact that you don’t need to use as much material to achieve proper insulation.

With new technologies developing in the field of spray foam, the chemicals used in the process of installation are becoming better for the environment as well. This includes blowing agents that have lower, to nonexistent, global warming potential. These blowing agents are known as HFO’s – short for hydrofluoroolifin – which have about the same potential for global warming as CO2. This is a huge improvement when compared to HFC’s – or hydrofluorocarbons – that were used traditionally.

In addition to advancements in application techniques that are helping spray foam to go green, there have also been improvements in the materials available for use as foaming agents. These days you can even find polyurethane spray foam which is made from soy or vegetable oil products rather than being petroleum-based.

Spray foam can also be considered environmentally friendly as it will last the lifetime of a structure. Something that cellulose and other types of insulation cannot claim. This means less waste and, in the long run, a reduced environmental impact than other types of insulation with shorter life spans. On top of all of that, it is completely resistant to fire and is impervious to damage from moisture as it provides an environment that is inhospitable to mold and mildew.

What about the least eco-friendly insulation?

When most people think of insulation they probably think of the pink fluffy stuff. This is typically fiberglass which may be among the least eco-friendly insulation out there. First of all, the production of fiberglass insulation requires an extremely energy-intensive process that requires as much as 10 times more energy than other environmentally conscious insulation alternatives. 

Additionally, the fibers contained within fiberglass insulation can lead to health issues including irritation of the skin, eyes, and respiratory tract. While fiberglass insulation can possibly be produced using as much as 30% recycled glass products, that pales in comparison to up to 85% which can be used by cellulose. 

Perhaps most egregiously, fiberglass is next to impossible to recycle. In fact, there is actually only one company in the entire United States that claims to be able to recycle fiberglass. They turn it into “wood-substitute planks”, but their website doesn’t list any locations where you could possibly drop off your old fiberglass for recycling, making it nearly impossible for the average consumer to dispose of it responsibly.

What’s more, fiberglass contains formaldehyde which is extremely toxic and can seep into the earth if it is put into landfills. You can see the conundrum here for anyone who is using fiberglass and trying to be environmentally conscious.

What’s the verdict?

It may be conceivable to argue that cellulose is the most environmentally friendly option available due to the fact that it is made from primarily recycled materials, and that it is biodegradable – essentially not contributing to landfill waste. However, when you take into consideration all of the factors at play, we think spray foam is the real winner in this equation. With all its added benefits; the fact that it never has to be replaced, its supreme insulation capabilities, and its resistance to fire, mold, and mildew, it’s hard to ignore the superiority of spray foam.  

Both cellulose and spray foam insulation are environmentally friendly insulating materials. While cellulose is made almost entirely out of recycled materials, spray foam is a more efficient insulating product while also using eco-friendly chemicals. Spray foam will have a higher R-value, produce less waste, and require less material for installation than other types of insulation which we believe makes it the best available option if you’re looking to go green with your home’s heating system.

If you are simply looking for the most eco-friendly insulation material, and that is your only criteria, then sure, maybe cellulose is the way to go. But if you want to be environmentally conscious while also looking for the best in all other attributes that make an insulation material great, you’d be hard pressed to find something that checks more boxes than polyurethane spray foam.