Building envelope is based on a new open woodframed building system Nordic Platform allowing for shorter delivery cycle than with typical construction. Special features of the system are 250 mm wood- frame with thermal break for exterior walls and trussed construction for internal floors. The walls have an air tight additional exterior insulation layer facing air cavity and wooden façade. Insulation thicknesses and corresponding Uvalues including thermal bridging in construction are 275 mm (U=0,15 W/m2K) for walls, 450 mm (U=0,15 W/m2K)for floor with crawl space foundation, and 500 mm (U=0,10 W/m2K) for roof. Windows are triple glazed with one argon gas filled sealed unit and one selective coating. Total U-value including frame is 1,1 W/m2K.