The Next Generation of Insulating Materials: Vacuum Insulation

Evacuation of the pores of nanoporous insulating material leads to a thermal conductivity in the range of 5 up to 10 mW/m·K (that means in comparison with conventional thermal insulation materials a by the factor 5...10 reduced thermal conductivity). Actual there are two different ways to design a building component using the principles of vacuum insulation: on the one hand the loadbearing vacuum insulating sandwiches (VIS) with its envelope made of stainless steel and on the other hand the vacuum isolation panels (VIP) with its enevelope made of a multilayer film. The technical lifetime of vacuum insulated constructions (defined as that period in which the thermal conductivity reaches an individual fixed limit) is one of its central questions and so it is discussed quite intensive. Depending on the type of vacuum insulating element different ways of calculating its technical lifetime exist: individual permeation coefficients of the single VIS-elements (based on standardized measurements, which are able to be determined after evacuation of each element) in connection with both the individual geometric dimensions as well as the type of core material allow to calculate an individual technical lifetime for every single VIS. The determination of the technical lifetime of VIP bases on statistical evaluation of single measurements and is therefore no individual value. Another important property of vacuum insulating elements used in building constructions is its resistance against mechanical loads and impacts. It is shown by examples tha