Polyurethane rigid
foam maintains its very low conductivity over time, and
has a useful life that extends to 50 years and more.
This can be explained by the permanence of the closed
cell structure over time.
Although there is usually a slight increase
in thermal conductivity over the initial, factory produced,
value, this is taken into account when the declared lambda
(thermal conductibilty), is stated for a product (eg in
CE mark). Declared lambda represents an average over the
expected lifetime of a building (at least 25 years). |
Increase
in thermal conductivity of PUR/PIR rigid foam insulation
materials in the first 10 years after manufacture (PUR/PIR
rigid foam boards blown with pentane over a storage
period of 10 years at room temperature.)
|
