TECHNICAL INSIGHT: INSULATION
THE LINK BETWEEN INSULATION MATERIAL AND PERFORMANCE
prevented. This is because it adapts to minor imperfections in the substrate, friction fits between building elements, knits together at the joints and will ThereareanumberofinsuqaDonmateriaqsavaiqabqeonthemarket:Asthe accommodate movement without reguqaDonsandstandardsgoverningbuiqdingdesignbecomestricterdarchitects creating gaps. All of which makes it easier andspecifiersmustunderstandhowthesemateriaqsactuaqqyperforminthe to install correctly, ensuring it delivers reaqorqd: w SodattM eary N dqass G ineraq M Wooqrodu P ctanager M atKnauf its intended thermal performance for the nsu I qaDondqooksatthreekeyfactorstoconsiderwhenspecifyinginsuqaDon: lifetime of the building. KNAUF INSULATION Another factor to consider is the deterioration of materials over time. here are two groups of mainstream But, in reality, declared performance Blowing agent migration is a known insulation materials; mineral wool doesn’t always translate into ‘as-built’ phenomenon where the blowing agents insulation (glass and rock), and oilperformance. In fact, an insulation material contained within the closed cells of PIR based rigid foam board insulation (PIR is with a lower lambda value may allow more and PUR insulation escape, reducing most common, as well as PUR, phenolic, heat to escape than one with a higher a product’s thermal performance. EPS and XPS ) . Architects and specißers maylambda once it’s been installed. As a result, manufacturers of these have a favoured material based on thermal That’s because some insulants are easier products are required by ISO and BS EN performance, but that performance may to install correctly than others, and incorrect standards to use accelerated ageing not be as clear cut as you think. installationcanleadtoairgapsthataœect test methods and statistics to minimise performance. Oil-based rigid PIR or phenolic this risk to long-term performance. Opt for real vs theoretical boardsdon¶tex,soanyimperfectionsin The thermal performance of EPS and thermal performance construction, such as mortar snots, mean the XPS can also be reduced by damage The thermal conductivity of a material boardswon¶tsitushagainstthesubstrate. from thermoplastic membranes, sun is known as its lambda value. In theory, They also need to be cut to size, and joints exposure and high temperatures. the lower the lambda value, the better must be sealed. Timbers can also bow and Unless it has become mechanically because less heat is lost through the shrink, creating air gaps that weren’t there damaged or saturated during a severe building fabric. So, PIR and phenolic at installation because the insulation and leak, research has shown that mineral wool insulation can be considered ‘better’ sealants cannot accommodate movement. insulation’s thermal performance does because they achieve a lower thermal In comparison, mineral wool insulation not degrade over time. This means it will conductivity in a thinner profile for a is inherently flexible. By installing deliver the expected level of performance given construction. it slightly oversized, air gaps are for the lifetime of the building.
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