Determining the Aging Performance of Vacuum Insulation Panels: Development of a Prediction Model
- Determining the Aging Performance of Vacuum Insulation Panels: Development of a Prediction Model
Vacuum insulation panels (VIPs) are increasingly being explored in building applications. Typically used in industrial processes such as aerospace engineering, cryogenics and refrigerator manufacturing, VIPs have been proven to provide a higher thermal resistance per inch than typical building insulation materials. However, there is speculation on the performance of these panels over an extended period of time due to various factors which gradually cause a reduction in thermal resistance. The purpose of this research project is to identify these variables and how they alter VIP performance over the product’s service life. Based on a thorough literature review, the critical components were interpreted to develop a numerical model which can predict the future performance of VIPs as they age, based on initial material properties. This model is intended to benefit designers and researchers in the construction industry; in understanding the potential for vacuum insulation to contribute to building envelope design.The results of calculation proved to be complementary to experimental results provided by the NRC, (initial calculated conductivities ranged from 4.17x10-3 to 4.56 x 10-3 W/mK, while measured conductivities provided by the NRC ranged from 4.12x10-3- 4.66x10-3 W/mK). While the results generated by the model do not provide exact numerical representations of the VIPs used, they do confirm that the model is a viable tool to estimate the approximate performance of the panels over time.The highest calculated conductivity was attributed to the low quality metalized (MF) VIP with a final conductivity after accelerated aging of 5.29 x 10-3 W/mK (14% increase from initial conductivity of 4.56x 10-3 W/mK). The best thermal resistance is attributed to the high quality aluminum (AF) VIP, with a final conductivity after accelerated aging of 4.17 x 10-3 W/mK, 0.22% less than its original conductivity. This identified that VIPs have the potential to be integrated within building applications, although their performance is dependent on the material composition of the panel.Some observations included that there is little difference between aluminum and metallic foils in their initial conductivity; however the aluminum foils represented in this report outperformed the chosen metallic foils over time, as they provided smaller gas and water vapour transmission rates. The core material variables with the greatest impact on performance were density and porosity. Some of the simulated panels exceeded the conductivity limit before the end of their service life, while others did not. Therefore the conclusion for VIP performance overall cannot be confirmed, although the development of standards within the industry would ensure high quality material integration within building systems.