In the 1960s a model for calculating the insulation of buildings was established by the scientific community.
This model relied on using the results from tests using a guarded hot box or a guarded hot plate
, laboratory equipment original created for traditional, thick, single layer insulation. This laboratory equipment measures the thermal conductivity
of these products at a steady state (in other words, a constant state), this means their capacity to prevent heat loss through conduction.
This single measurement for heat conductivity is not sufficient to categorise the overall thermal performance of thin multifoil insulation.
Unlike traditional thick insulation - which mainly work to prevent heat exchange through conduction - the specific nature of thin multifoil insulation, combined with its application between two air gaps, forces energy to be transmitted via radiation rather than by conduction or convection. Heat exchange through conduction plays only a minor role in the way thin multi-foil reflective insulation works.