Financially optimum insulation thickness of external building walls

The building sector accounts for nearly half the energy consumption of Uzbekistan, with the residential energy consumption being much greater than that of even the most developed European countries. This is mainly attributed to the very low cost of energy in the region that, in combination with the lack of subsidies, offered no incentive for energy conservation measures. However, the price of energy has been rising at an alarming pace over the past few years, making building energy saving measures a nationwide concern. In this paper, we investigate the financially optimal insulation thickness for the most common external wall configurations using the two most commonly used building insulations materials in Tashkent, Uzbekistan, expanded polystyrene and mineral wool. Annual heating and cooling transmission loads are being calculated based on transient heat flow through the external walls and by using hourly climatic data. Additionally, we performed a financial analysis for each wall configuration and orientation, as well as for various thicknesses of insulation material. Depending on the wall type and orientation, the optimum insulation thickness was found to be between 3.75 cm and 11.0 cm. Furthermore, a sensitivity analysis indicates whether changes of the economic parameters affect the optimum insulation thickness.