Moisture & Exacerbated Heat Loss / Gain
It is important to understand the different properties of the insulation
you use, because the measured performance of the material in its ‘fresh
from the factory’ state may not be what you get in a real
For instance, moisture can end up in insulation in a number of
- liquid water penetration through the vapour barrier
jacket or any weather protection layer; or
- vapour penetration
through the vapour barrier jacket and resulting condensation
on chilled services.
Insulants are affected in different ways and degrees by this.
For example, only 1% moisture content by volume within mineral
fibre insulation can increase its thermal conductivity by up to
The closed cell construction of high performance rigid phenolic
insulation, on the other hand, makes it almost impervious to moisture,
and its thermal conductivity remains largely unaffected.
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