In this work, the thermal performance of three different wall configurations was examined by hot box measurements and numerical simulations. Vacuum insulation panels were sandwiched between traditional insulation in walls where the load-bearing elements were standard 36-mm-thick wooden studs, I-profiled studs and U-profiled studs. The measured mean values of the thermal transmittance (U-value) were 0.09 W/m2·K with 36-mm-thick wooden studs, 0.10 W/m2·K with U-profiled studs and 0.11 W/m2·K with I-profiled studs. The comparison of the three wall structures has shown that with such low U-values, the numerical simulations are more sensitive to the accuracy of the dimensions and thermal conductivities used as input. This required measurements of the thermal resistance of the fibreboard in two directions, the thickness and thermal resistance of the vacuum insulation panels and the thermal resistance of the 36-mm-thick wooden studs and the mineral wool.