More sustainable and eco-friendly insulation materials: what options are available?
If you bought a house with a renovation obligation or you’re thinking about finally realising those energy-efficient renovation plans you’ve been dreaming of, you’re probably already aware that it’s best to start by improving your home’s insulation. That’s not only good for your wallet, it’s good for the environment too. If you’re interested in using more eco-friendly insulation materials, check out your options here!
First things first: how are you planning to insulate?
Before choosing your materials, it is important to first determine your preferred insulation method. Will you insulate your façade from the inside or the outside? Or will you go for cavity wall insulation? The materials you choose depend on your preferred insulation method. For some applications, the insulating material must be able to withstand moisture , or you may want the material to be as thin as possible to save space.
Insulation value: an important indicator
When you dive into the wonderful world of insulation, you need to consider three factors: the lambda value, the R-value and the number of centimetres you can/need to install.
- The lambda value (λ) indicates how well the material conducts heat. The lower the lambda value, the greater the insulating capacity. The best insulating materials have a lambda value of about 0.022.
- The R-value measures a material’s thermal resistance. The higher the R-value, the greater the insulating effect of the material. Anything above 3.5 is considered a good R-value.
- The thickness refers to the number of centimetres of material you install and helps determine the insulating value. To determine the R-value, the following formula is used: R = thickness/λ. In short, you should choose material with a low lambda value and a high R-value. For most materials, you need to install at least 10 centimetres.
The classics: mineral wool and PIR/PUR
The market leaders in insulation material are mineral wool and PIR and PUR boards, both of which have lambda values ranging from good to excellent: 0.031-0.044 W/mK for mineral wool and 0.021-0.028 W/mK for PIR and PUR boards. Both materials are suitable for most applications and are also budget-friendly: their effective insulating properties mean the required thickness remains limited.
If your insulation material needs to be highly moisture-resistant, XPS might be a suitable option. Some manufacturers produce XPS from recycled EPS (polystyrene foam), making it a more environmentally friendly choice.
Eco-friendly alternatives
To keep your building or renovation activities as environmentally friendly as possible, another important thing to consider besides these values is the environmental impact of the materials’ production processes.
Hemp: the undisputed environmental champion
Hemp is a fast-growing plant used in construction materials, including insulation boards. Cultivating hemp not only has a low environmental impact, it has many benefits too:
- Hemp removes CO2 from the air through photosynthesis
- It requires very little to grow
- It is completely biodegradable
- It has an average insulation performance
- It has low fire-resistance, which is why additives are sometimes added, which in turn are less environmentally friendly
- It is fungicidal and antibacterial, making it beneficial for your indoor climate
It has a lambda value between 0.038 and 0.042
The required thickness for an R-value of 3.5 is roughly 14 cm
Indicative price per sq.m.: 80 – 120 euros
Jeans: old trousers in your walls
Jeans are an environmentally harmful product: the production of a single pair of jeans requires up to 8 000 litres of water and many chemicals. In addition, jeans are difficult to recycle due to metal rings on the pockets, leather patches, added polyester to make the fabric stretchable, and so on. All these different components complicate the recycling process. As a result, around 75% of old jeans end up in incinerators. You can help counter this by using old jeans as insulation material.
Insulation boards made from recycled denim…
- Reduce waste
- Are manufactured using an ecologically optimised production process
- Can be recycled again
- Also have acoustic insulating properties
Lambda value: around 0.037 W/mK
The required thickness for an R-value of 3.5 is roughly 13 cm
Indicative price per sq.m.: 30 – 50 euros
Cork: a renewable source of insulation material
Just like hemp, cork is another renewable source of insulation material. However, we should mention that the bark of the cork oak can only be harvested every nine years. As a result, cork production can’t just be increased at a moment’s notice. A long-term plan is necessary. That being said, cork trees can live for around 200 years, so they last a very long time. There’s also good news: projects are underway to recycle cork bottle stoppers into insulation material for interiors.
Cork is…
- Naturally fire-resistant, without additives
- Acoustically insulating
- Fully recyclable
- Unappealing to rodents
Unfortunately, it is also a very expensive insulation material. On the other hand, it lasts an extremely long time (around 50 years).
Lambda value: 0.038-0.040
Required thickness for an R-value of 3.5: roughly 14 cm
Indicative price per sq.m.: 90 – 130 euros
Sheep’s wool: not as sustainable as you might think
Being a natural product, you would expect sheep’s wool to be highly sustainable. However, the sheep providing the wool emit significant amounts of greenhouse gases (partly due to the production of feed for the sheep) and therefore have a major impact on the climate. In addition, the use of chemicals during the cleaning process also impacts the climate, as does the water used in the process.
Wool seems sustainable on the surface because…
- It comes from a renewable source
- It is biodegradable
- It can absorb up to 33% of its own weight in moisture without losing its insulation value
Lambda value: 0.035-0.040 W/mK
The required thickness for an R-value of 3.5: 12-14 cm
Indicative price per sq.m.: 20 – 25 euros
Mycelium: the wondrous fungal network
Mycelium is a promising and sustainable insulation material that is gaining increasing attention in the construction industry.
- Mycelium grows on agricultural waste streams (substances such as hemp, flax and straw are used as a basis)
- Its production requires minimal energy consumption
- It has excellent thermal insulation properties and good acoustic insulation properties
- It is a circular and biodegradable material
- It can grow into any shape desired, minimising waste during installation
- It has good fire-resistant properties
- It is also moisture-resistant
Lambda value: around 0.039 W/mK (depends on density)
Required thickness for an R-value of 3.5: roughly 13.5 cm
Indicative price per sq.m.: 55 – 75 euros
Best of luck with insulating your home
As you can see, you have quite a few options to insulate your home in an environmentally friendly way. The two most important things to consider when choosing your materials are whether they are space-saving and budget-friendly. We wish you the best of luck! Don’t forget you can always reach out to us for help. Use Setle to find out how much your renovation will cost you, check out our various financing options for your project or work out your renovation loan
Keep your eye on the ball with KBC
Housing, work, life: they all bring challenges. At KBC, we like to keep you up to date with the latest developments in housing, energy, sustainability and mobility. For example, you might like to check out our handy checklist for bathroom renovations of read more about the relaxed renovation obligation.