Insulation Question

tunes81

Why if Kingspan has a thermal conductivity of about 0.023 and air is 0.020
that Kingspan is better at insulating than air?
Its obvious that it works but why?

patrido

air is actually a very good insulator. the first cavity walls had no insulation in them, yet they kept the house much warmer than an equivalent thickness of concrete.

the trouble with air though is keeping it still. so in most situations the air moves and takes the heat with it.

the major factor in determining how effective insulation is is how much air (or other low conductivity gas) that can be trapped within the structure of the insulation as well as how well it is trapped. kingspan is very effective because it's closed cell structure traps billions of little air compartments within its structure.

fibreglass wool also traps lots of air within it, but it is not sealed quite so well. air can move in and out more freely, and therefore it is not as good an insulator.

the air trapping principle also explains why squeezing fibreglass into a smaller area (such as compressing 8 inches of fibreglass into a 6 inch joist) is a waste of time and money...

because by compressing it, you reduce the number of air spaces within the insulation, so, it's less effective.

tunes81

Cheers Patrido,
i understood that its the air in the kingspan that insulates but never copped that its the fact that it stops the air from circulating which makes it more effective than just air on its own!!