Thermal performance and optimum insulation thickness of building walls with different structure materials

► The study investigates thermal performance and optimum insulation thickness of walls. ► The investigation is carried out by using an implicit finite difference method. ► Five different structure materials and two different insulation materials are selected. ► The optimum insulation thicknesses, energy savings and payback periods are determined. ► Results obtained under dynamic conditions are compared with the degree-days method.