The article examines technological and structural solutions for walls, roofs, floors in order to find the most effective barriers for each material and its thickness. Thermal insulation materials are the key factor to be considered in energy efficient buildings. Selected alternative materials are mineral wool, polystyrene and polyurethane foam. Thermal parameters, economic and technological indicators are compared within the envelope. The optimal thickness of the envelope component is found by calculating every envelope option by means of test utility method. The most efficient insulation material is determined by the simple additive weighting (SAW) method. The optimal thickness of insulation materials: 400 mm for the roof, 300 mm for walls and 300 mm for floors. The most effective materials are as follows: polyurethane foam for the roof, polyurethane foam for walls and polystyrene for floors.