This thesis investigates the accuracy of industry standard calculation methods, and two and three-dimensional numerical simulation techniques, to predict the thermal resistance of a wall assembly containing vacuum insulation panels (VIPs) and thermal bridges. The calculation methods and numerical simulations were used to predict the thermal resistance of a wall assembly that was tested in a guarded hot box. The calculation methods and two-dimensional simulation scenarios which did not include VIP edge thermal bridges resulted in a minimum overestimation of 38%. Accounting for the thermal bridges using the average joint width between panels reduced the minimum overestimation to 13% (modified zone calculation method) and 20% (two-dimensional simulations). The three-dimensional simulations overestimated the thermal resistance by 14%. Overall, the most reliable predictions of thermal resistance were determined through 3D simulations and the modified zone method in combination with the thermal bridge effect due to the average joint width between VIPs.