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The 8 criteria for choosing an insulation material

In any construction project, whether ecological or standard, insulation plays a key role in ensuring optimal comfort for occupants and saving energy. To make the right choice from the long list of insulators available on the market, discover our criteria.

In passive house construction, excellent insulation of the external building envelope is one of the 5 pillars of this building concept. Poor insulation can lead to high heat loss, discomfort in the house, and even signs of unhealthiness, such as mould. It is therefore necessary to pay particular attention to the choice of insulation material, based on 8 criteria:

Embodied energy

In a green building project, it is important to consider the embodied energy of a material, i.e. the energy required to extract, manufacture and transport the material. Bio-sourced insulation materials are largely known for its low embodied energy.

Low embodied energy insulation: linen fibre, hemp fibre

Thermal performance level

To identify the thermal performance of an insulation, two main indicators should be taken into account: 

  • Thermal conductivity (lambda – λ): The ability of the material to transmit heat by conduction. This determines the insulating capacity of a material: the lower the lambda coefficient, the more insulating the material.
  • Thermal resistance (R): The ability of the material to resist to cold and heat. The R-value depends on the thickness of the material and the thermal conductivity.

Insulation with low lambda coefficients: hemp fibre, cork fibre

Humidity control

The humidity control of an insulation material is its ability to absorb and release humidity efficiently without deteriorating. Insulation with good humidity control ensures dry and healthy indoor air for the occupants.

Insulation with good humidity control: wood fibre, cellulose wadding

Non-flammable or fire-protected

Some insulation materials are considered non-flammable and can even protect against fire by slowing the spread of flames. This is the case for some mineral insulation materials (made from sand, recycled glass, clay, etc.).

Non-flammable insulation: foam glass, rock wool

Resistance to rodents

Rodents can cause serious damage to a building’s insulation by burrowing into it, which will significantly alter the insulating properties of the material. If possible, make sure you choose an insulation that will also be resistant to insects.

Rodent-resistant insulation: expanded cork, hemp

Expanded cork © Amorim Cork Insulation

Health risks

Some insulation materials can cause respiratory problems (e.g. rock wool) or emit toxic substances in case of fire (e.g. polyurethane). Insulation has a role to play in maintaining healthy air in the home.

Non-harmful insulation: wood fibre, hemp


For insulation to last, it must be resistant to external aggression (rodents, insects or humidity) but also not settle over time (which is the case with cotton wool or linen, for example).

Insulation with good durability: wood fibre, straw

Acoustic performance

Although we tend to focus on thermal performance, some insulating materials also have excellent acoustic performance, to minimise noise pollution at home.

Acoustic insulation: cork, coconut fibre 

Before choosing an insulation material, think about the installation! Depending on the location of the insulation, certain forms are to be preferred (bulk, panel, roll, etc.), and may influence the choice of material. Finally, be careful when installing the insulation: if it is badly installation, all the properties of the material will be altered.

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Photo: Universal Eye on Unsplash

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