Optimal Thermal Insulation Thicknesses of External Walls Based on Economic and Ecological Heating Cost

The present study introduces the concept of ecological cost of heating modeled on the economic cost of heating. A method of determining these costs is also proposed. This method allows for an analytical description of the ecological as well as economic net present value of a thermal insulation investment. Consequently, it is possible to determine the optimal values for ecological reasons of the heat transfer coefficient of the building external wall and the thickness of thermal insulation. The present study uses life-cycle assessment (LCA) analysis to determine the environmental impact of thermal insulation materials used to insulate the external vertical wall and to determine the environmental impact of thermal energy production in the energy phase of the building's life cycle. Various variants characteristic of Polish conditions were studied. Different types of construction materials of the wall, types of heat sources, thermal insulation materials and climate zones occurring in Poland were considered. For all analysed variants, the obtained thermal insulation thickness, optimum for ecological reasons, was much larger than the optimum for economic reasons. Even at the thickness of thermal insulation optimum for economic reasons, the investment was profitable for ecological reasons, i.e., a reduction in environmental load was obtained as a result of the thermal insulation investment. On the basis of the conducted study, it can be concluded that it is preferable to use thermal insulation thicknesses larger than required by current regulations and larger than optimum for economic reasons. The ecological benefits of thermal insulation investments are then significantly greater, with not much smaller economic benefits.