Stockholm lies at the top in Europe in terms of population growth. It is growing from 30,000 to 40,000 residents each year and therefor puts high demands on the regions development. One of the governments reactions to this housing problem was to approve a bill that would simplify the regulatory framework in the planning and building act. It will among other permit owners of a one-or two family houses to build a 25  compliment housing without a building permit, so called attefallshus. In this final project, a small 25  house is designed. The house was designed to have thin exterior walls to maximize the indoor living space and also to fulfill all the Boverkets regulations for permanent housing. Vacuum Insulated panels were used as an insulation material in the envelope to achieve the extra thin exterior walls to maximize the living space. Various different simulations were done to simulate: Heat- and moisture transfer through the exterior walls, thermal bridges, energy calculations and the daylight factor inside the house. Additional calculations were done in Excel to compare the mean U-value calculated in simulations. The moisture transfer simulation did show that there should not be any moisture problems in the exterior walls. The mean U-value calculations in Excel and in the simulations showed values less than the limitations of Boverkets building regulations.