Optimum Insulation Thickness Based on Energy Carriers Different Tariffs in Climatic Condition of Tehran

The optimal insulation thickness is a function of the insulation initial cost and the cost of energy carriers for the internal space heating and cooling due to heat transfer from the wall. In Iran, by allocating subsidies to the energy sector, tariffs for energy carriers are sensibly lower than global prices. In order to determine the insulation optimal thickness, energy carrier tariffs were considered variable according to consumption. Electricity and gas costs were divided into 4 ascending tariffs for low, moderate, high, and very high consumption cases. In addition, the case of energy carriers without subsidies was also examined the 5 . The outer wall consists of a typical hollow with 20cm thickness, insulated with an expanded polystyrene layer, placed the outside. Heat load due to heat transfer from the external wall was calculated by using EnergyPlus simulation software in different geographical directions and different thermal insulation thicknesses in Tehran climate. The optimum insulation thickness was determined based on the total cost over the lifetime of 30 years. According to the results, in the first tariff, which refers to low-cost subscribers, the use of thermal insulation in some geographic directions does not allow the payback period over a lifetime. In other directions, economic savings are low and . For higher tariffs, the optimum insulation thickness increases. In the 2 5 , the thermal insulation thickness from 6 to 18 cm. Also, the calculated payback periods of these configurations are between 6 and 28 years.