Economic and environmental impacts of insulation in district heating pipelines

► In this study, the economic and environmental evaluations of thermal insulation in district heating pipeline are discussed. ► Based on LCC analysis, the optimum insulation thickness, energy saving, payback period and emissions are calculated. ► About three times more energy saving results by making 200 mm nominal pipe instead of 50 mm. ► Considering the economical and environmental advantages, the geothermal energy is a better choice and then fuel-oil.