Prediction method of the long-term thermal performance of Vacuum Insulation Panels installed in building thermal insulation applications

Vacuum Insulation Panels (VIPs) are super-insulating products that can be used for different applications. When they are used for building thermal insulation, they have to maintain a very high thermal performance in long-term. The initial thermal conductivity of VIPs is around 4 mW.m(-1).K-1. This very low value will increase in time, depending on the nanoporous property of the core material and on the barrier envelope efficiency which prevents the increase of moisture and internal pressure. To estimate the long-term thermal performance of VIPs, modelling is required. Simulations have shown the very great importance of the core material characteristics, and the external temperature and humidity conditions. That is why it is necessary to study the VIPs behaviour with realistic solicitations in service life for each VIP configuration. This paper proposes a methodology for determining the long-term thermal performance of VIPs when they are installed in envelope components for various building thermal insulation applications. All the methodology including the climate conditions, the building modelling and the insulation systems, is described. Severity criteria and performance indicators are proposed in order to estimate the thermal efficiency of VIPs in various applications and climates. (C) 2018 Published by Elsevier B.V.