Use of multi-foil insulation in buildings: a review

The use of multi-foil insulation for building applications, especially in roof structures, has attracted increasing interest because it blocks different heat transfer routes through its multi-layer designs. This is particularly the case with radiative heat transfer, due to the shiny foil layers present on each face and in between insulation layers. However, to date, there is a lack of conformance in the thermal performance of the system between the tests by investigators and the claims made by the manufacturers. This is due to different measuring methods being used and different conditions that are applied. This paper reviews the construction of multi-foil insulation systems and the analyses of their thermal performance as presented by manufacturer and investigators using in situ tests and product tests, and focusing on the different conditions for the tests to be conducted. In addition, the further in situ tests with the considerations of long-term testing, using different weather conditions and exactly identical setup of equivalent tests to show repeated, more convinced and robust results are suggested.