Thermal conductivity for Optim-R vacuum insulated panels


The λ-value or thermal conductivity of a material indicates the ability of that material to conduct heat and is measured in units of W/m·K. The lower this number, the better insulator the material is because materials with low thermal conductivities do not easily allow heat energy to pass through.

We state that our Optim-R Vacuum Insulated Panels have an aged design value thermal conductivity of 0.007 W/m∙K. (which we round up to the nearest mW). This is 3 times better than existing commonly available high performing insulation materials and is the lowest lambda value of all our insulation products.

But why aged?

There are several different values which we could have used for the lambda value of our Optim-R panels.

The first is the centre of panel. As the name suggests, this is the initial value measured at the centre of an Optim-R vacuum insulated panel when it comes off our production line. For our Optim-R panels this comes to approximately 0.005 W/m∙K. But this is not representative of what the system will be when it is fitted.

We don’t use this.

Instead we take into account other factors to make sure that the customer is informed of the accurate lambda value of Optim-R as a fitted system and ensuring that we are reporting the thermal performance of the vacuum insulation panels responsibly.

We report a value that:

  • Takes into account aging. This adds approx. 1mW, to the lambda value of the board, taking into account the performance over 25 years.
  • Edge Effects. Again these add approx. 1mW to the thermal conductivity of the board, but shows the effect of the increased thermal conductivity around the edges of the board.

All of the these factors mean that we use a thermal conductivity of the Optim-R system of 0.007 W/m·K.

This is the most reliable way, in that is shows the performance of whole system over 25 years. It doesn’t just tell you what the thermal conductivity is when it comes out of our factory, it shows you what you get when it is installed.

But you don’t have to rely on our word for this – we’ve gained a BDA agrément, accepted by the NHBC, allowing for faster approval of projects. Take a look at our Optim-R webpage for more information.

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Kingspan Insulation is a market leading manufacturer of optimum, premium and high performance rigid insulation products and insulated systems for building fabric and building services applications.

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