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How to specify for better energy efficiency

As regulations tighten, it’s important to understand why insulation plays such an essential role in maintaining a building’s energy efficiency.


Creating an energy efficient building starts with the envelope

A continuous, correctly installed layer of insulation, supported by airtightness measures, minimises wasted energy and prepares a building for renewable energy sources.

It does this by creating a barrier that reduces heat transfer through processes called conduction and convection. Without the right insulation in place, heat can pass more easily from the inside of a building to the outside, resulting in poor energy efficiency.

A ‘Lambda value’ (or K-value) measures how easily heat passes through insulation. The lower the Lambda value, the less heat is lost through the material.

How insulation works graph

A low Lambda isn’t enough.

Defining the thermal performance of insulation based solely on Lambda values assumes a perfect installation. But in the real world, best practice isn’t always followed, and a wall’s inner leaf isn’t always flat…

If a surface isn’t perfectly uniform, rigid board insulation won’t sit flush against it. This can lead to air gaps, even the smallest of which can compromise insulation’s performance. And if the joints between boards are not taped with precision, further gaps can form.

Installation Pitch Roof Inuslation

Mineral wool insulation is different:

  • Interwoven structure delivers high thermal efficiency.

  • Flexible nature adapts to imperfect surfaces, fully filling the cavity.

  • Where sections meet, they ‘knit together’, minimising gaps.

  • Mineral wool’s age does not impact its performance.

  • Won’t expand and contract with temperature fluctuations.

  • Won’t absorb moisture, which can lead to degradation.

  • Knauf Insulation’s glass mineral wool has Lambda as low as 0,030 W/mK.

  • Knauf Insulation’s rock mineral wool has Lambda as low as 0,033 W/mK.

Learn about the science:

To achieve true energy efficiency, the real world performance must live up to the design.

Real performance relies on correct installation and mineral wool’s forgiving nature makes it easier to ‘get right’.

For added assurance, Knauf Energy Solutions can advise on how to achieve the best energy performance gains, for both new builds and renovations, through improvements to features like insulation, heating, and glazing. Their innovative sensor technology allows the energy performance of occupied homes to be monitored, ensuring the energy saving measures deliver on their design.

Learn about Knauf energy efficiency solutions:

Real world energy measurement and saving

But it’s not only about energy efficiency - mineral wool is ideal for buildings of every type and height, thanks to its unique combination of benefits.


Learn about specifying with mineral wool insulation:

Learn about the importance of insulation for:

Acoustics Fire safety