In this paper it is attempted to study the effect of different foundation designs of passive house on the resultant thermal bridges, at the junction between a wall and a slab on grade. The linear thermal transmittances of some newly developed foundations of passive house are determined. The compared foundation designs are L-element, U-element and foundation with foam glass technique. It is found that the special design of passive house foundation can considerably influence the heat flow through thermal bridges. The calculated linear thermaltransmittances of L-element, U- element and foundation with foam glass are 0.085 W/mK, 0.074 W/mK and 0.031 W/mK, respectively. In this context, it is proposed a new foundation design of passive house, which has relatively low heat loss through thermal bridges, calculated as 0.031 W/mK. The results are compared with the “default” ISO values used to evaluate the effect of thermal bridges in typical buildings. It is found that there is large difference between the calculated linear thermal transmittances at the investigated foundationsof passive house as compared to typical buildings.