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How to specify for better thermal comfort

Achieving better thermal comfort starts with insulation – and not just in winter.

We need comfortable, safe, healthy buildings in summer too, and as our climate continues to heat up, that need has become more urgent. Our buildings must adapt through holistic design. Combining heating and cooling measures with a well-insulated envelope means you can make insulation do more. It will protect your buildings’ internal environments, enabling thermal comfort for occupants all year round.


What matters when specifying insulation?

There are two key factors to consider when specifying insulation for thermal comfort:

1. R-value

When it comes to protection against overheating, there is negligible difference between insulation products with different densities and heat capacities. What really matters, is your insulation’s ability to resist the transfer of heat – its R-value.

In theory, the higher the R-value, the higher the thermal resistance. In reality, two insulation products with the same R-value can actually perform quite differently, due to poor installation or degradation over time. This difference between designed and as-built performance is known as the ‘performance gap’.


2. Real world performance

Graphic Specify For Thermal Comfort

How likely is it that your insulation will achieve its R-value, once installed?

Some insulation products are more difficult to install than others, under real site conditions, increasing the risk of a performance gap. For example, if a surface isn’t perfectly uniform rigid board insulation won’t sit flush against it. This can lead to air gaps, which can compromise thermal comfort. If the joints between boards are not taped with precision, further gaps can form, enabling more transfer of heat.


To achieve the consistent, predictable building envelope that better thermal comfort relies on, insulation needs to perform in the real world, not just on paper.


Mineral wool is ‘buildable’ by nature

Mineral wool’s buildable nature makes it the ideal insulation material for achieving real-world thermal comfort and its unique combination of benefits makes it suitable for buildings of every type and height.


  • Flexible form adapts to imperfect surfaces.
  • Adapts to settlement/ movement over time, maintaining close contact.
  • Fibrous surfaces friction fit tightly together, minimising gaps.
  • Can be easier to install correctly than other mainstream insulation materials.
  • Thermal performance doesn’t degrade over time.
  • Won’t expand and contract with temperature fluctuations.
  • Won’t absorb moisture, which can lead to degradation.

Flexible Structure Mineral Wool Icon

Flexible structure

adapts to movement and imperfect substrates.

Friction-Fit Fibrous Edges Mineral Wool Icon

Fibrous edges

friction-fit tightly together to minimise gaps.

Long-lasting Performance Mineral Wool Insulation Traps Air Icon

Works by trapping air

so performance does not degrade over time.

Learn how to make insulation do more for:

Energy efficiency Acoustics Fire safety