Vacuum Insulation Panels (VIPs) are characterised by very low thermal conductivity, compared to tradi-tional insulating materials. For this reason, they represent a promising solution to improve the thermalbehaviour of buildings, especially in the case of energy retrofitting (where a higher performance andless thickness is desirable). VIPs are insulating components in which a core material is surrounded byan air tight envelope which allows a high degree of internal vacuum to be maintained. Such features,on the one hand, allow excellent thermal insulation properties to be achieved, but, on the other, requirethe manufacturing of prefabricated panels of fixed shape/size. This means that the use of these superinsulating materials in the building envelope involves the problem of joining the panels to each otherand of fixing them onto additional supporting elements.As a result, purposely studied supporting structures or systems are required. However, these structuresand systems cause thermal bridging effects. The overall energy performance of the resulting insula-tion package can therefore be affected to a great extent by these additional elements, and can becomesignificantly lower than that of the VIP panel alone.In order to verify the incidence of thermal bridges on the overall energy performance of an insulationsystem that makes use of VIP panels, an experimental campaign has been carried out using a heat fluxmetre apparatus and analysing different joint materials/typologies. First, a measurement method wasproposed, tested and verified on the basis of data from the available literature. A series of measurementson different samples was then performed. The experimental results were then used to calibrate andverify a numerical model that allows the performance of various “VIP packages” to be predicted and theperformance of the overall package to be optimised.