Creating a vacuum practically eliminates convection, since this relies on the presence of gas molecules able to transfer heat energy by bulk movement.
[4] The thermal resistance of VIPs per unit thickness compares very favourably to conventional insulation.
[5] For instance, standard mineral wool has a thermal conductivity of 0.044 W/(m·K),[6] and rigid polyurethane foam panels about 0.024 W/(m·K).
Conventional insulation does not depend on the evacuation of air for its thermal performance, and is therefore not susceptible to this form of deterioration.
So far this high cost has generally kept VIPs out of traditional housing situations, However, their very low thermal conductivity makes them useful in situations where either strict insulation requirements or space constraints make traditional insulation impractical.