Different types of lambda

3 April 2017 Kingspan Insulation UK
What is a lambda value

This week, we’re talking about lambda values.

Today we’re launching two new products within our Kooltherm K100 range, each of which have a lambda value of just 0.018 W/m·K across all thicknesses.

When you compare this with the Kooltherm K-range and our Therma range, which achieve between 0.020 – 0.023 W/m·K and 0.022 – 0.026 W/m·K respectively (depending on the product thickness), you can see the difference. But what exactly does it mean, and why is it important?

The term ‘lambda’ is used interchangeably with ‘thermal conductivity’, and measures how well a material conducts heat in units of watts over metres Kelvin (W/m·K). For insulation, the lower the lambda value, the better the thermal performance.

Lambda values are important for completing U-value calculations, which in turn help you to meet Building Regulations.

You might have heard of some other types of lambda too. This BBA guidance document covers everything you need to know on the topic, but we’ve also summarised for you below.

  • An aged lambda value predicts the thermal conductivity of insulation over a 25 year period.
  • Lambda 90/90 is a statistical analysis to define the thermal conductivity that 90% of insulation production should equal or better, with a 90% confidence limit.
  • Declared lambda is lambda 90/90 combined with an additional correction for an aged lambda value.

Kingspan Insulation Ltd

For queries relating to insulation boards, cavity closers or membranes.





General enquiries: 01544 388 601

Technical advice: 01544 387 382

We use cookies on our website www.kingspan.com. To find out more about the cookies we use, or to change your cookie preferences i.e. to remove your consent to our use of certain categories of cookies, please visit our Cookie Policy & Control page.

Please click "Accept and close" to accept the use of cookies on our website. If you do not click "Accept and close" but continue to use this website: you thereby consent to the use of all Kingspan's cookies and third party cookies for the purposes of improving performance, improving functionality and audience measurement, in accordance with the terms laid out in our Cookie Policy & Control page; and we will assume that you have read and understood our Cookie Policy & Control page.