Insulation is a sustainable practice, by definition. But not all materials are quite as eco-friendly as you might think. In this guide, we’ll run through everything you need to know about sustainable insulation – from materials available to the issues with traditional insulation.

Isn’t all insulation sustainable?

Unfortunately, the answer is no. When installed correctly, all insulation materials will retain heat meaning you don’t have to use as much energy. In that sense, they’re better for the environment. But that’s not the case when they need to be replaced or when you look at how they’re produced.

Let’s take polystyrene insulation as an example. Polystyrene is made using suspension polymerisation – a process that combined ethylene and benzene. Both of these chemicals are found in petroleum, which is the most common starting point of polystyrene manufacturing. As a finite natural resource, that’s certainly not a sustainable option.

Advocates of this insulation material will boast about its longevity. However, this is also one of the downsides for the environment. Once it’s completed its lifespan, polystyrene insulation is rarely reused or recycled. Because polystyrene is technically a plastic, it can last for hundreds of years in landfill.

As you can see, production and disposal are both important for sustainable insulation materials. With that in mind, let’s take a look at some of the better options for the environment…

4 sustainable insulation materials

Cork

While there might be questions raised about some types of insulation on this list, that’s not the case for cork. It’s undoubtedly a sustainable insulation material in terms of both its production and disposal.

Cork is sourced from cork oak trees, which grow in countries like Portugal and Spain. However, rather than felling those trees, the cork-rich bark can be stripped with the trees left to regrow their bark. This process actually makes them absorb more carbon dioxide, so it’s a big win for the environment.

From there, slabs of cork are harvested, cleaned and softened, from which ‘corks’ are typically punched out for wine bottles. The remaining cork material can then be ground into granules and used for other applications like insulation. That comes in a few different forms:

• Internal wall coating
• External render
• Thin rolls
• Bulkier boards or panels

As for disposal, cork is totally biodegradable. With the right application, it’s long-lasting – for example, SprayCork is guaranteed for 25 years – so you’re not sending lots of waste to landfill. Any waste you do have won’t take hundreds of years to break down.

Wool

Wool is synonymous with warmth, which is probably why other forms of insulation like “mineral wool” take its name. Unfortunately, mineral wool is not sustainable because it requires such high temperatures to produce it.

On the other hand, real wool from sheep can be sustainable. It’s recyclable and biodegradable, so there are no issues for disposal. However, its value as sustainable insulation depends on how it’s sourced. Quite simply, are sheep being farmed sustainably?

This depends on a number of factors, including land use, animal feed and the locality of the wool, so it can be a little complex to ensure your wool insulation is sustainable. Another downside to this is that using real sheep’s wool as insulation is a lot more expensive than other options.

Wood wool

Another type of insulation that uses “wool” in its name is wood wool, which is certainly more sustainable than its mineral counterpart. It’s made from wood shavings, which are mixed with a binding agent and then compressed into panels before drying.

They offer good insulation and fire resistance with no concerns when it comes to disposal. However, the sustainability of wood wool insulation does depend on the source of the wood. Sustainable forestry practices like selective logging and replanting can ensure that wood wool insulation is much more eco-friendly.

Hemp

Hemp insulation isn’t a million miles from wood wool. It uses woody fibres from hemp plants which are pressed into both insulation boards and batts. Unlike wood, hemp is fast-growing with plants reaching full growth in just 100 days, so there are definitely no concerns about sourcing the material. It’s also biodegradable, making disposal sustainable too.

Choosing the right sustainable insulation for you

If you’re looking for sustainable insulation materials, there are a few options to choose from, which we’ve touched upon above. So, how do you choose between them for your property? Here are some factors to consider…

Application

First, there’s the application. In other words, where are you insulating? The likes of wool insulation and hemp batts are suitable for loft insulation and cavities on new build walls. If you’re looking to insulate existing walls internally, you’ll need insulation boards made which can be made from hemp, wood wool and cork. Alternatively, you can use an internal coating of sprayed cork.

Externally, insulation boards may also be used, though an external coating using cork can save you space, as below. There are also specific applications like insulating a conservatory roof, where only certain products can be used.

Space

Insulation can take up more space than you think. That’s not an issue with loft insulation or cavity walls, because it’s space you can’t or don’t access. However, it’s an issue for both internal and external walls.

Externally, bulky insulation panels may force you to adjust fixtures like windows, doors, gutters and downpipes which can add to the disruption and cost of the job. On the inside, that issue costs you valuable living space given that you have to install bulky boards plus an overcoat of plaster.

In stark contrast, SprayCork is applied in a thin layer so there’s no impact on fixtures outside your property or space inside.

Budget

Last but not least, there’s your budget. Real wool and wood wool are particularly expensive compared to the more affordable hemp insulation, for example. As well as the cost of sustainable insulation materials, it’s worth considering the extra costs of installation – such as adjusting gutters like the above.

Sustainable cork-based insulation

Cork is amongst the best sustainable insulation materials available. At CorkSol, we specialise in a sprayed cork solution that can be used on internal walls and applied externally to reduce your heating bills by 15%.