A Comparative Life Cycle Assessment of Residential Heating Systems in Tehran, Iran

Abstract

Environmental pollution from different gas heating systems in residential buildings has significant impacts, especially in urban areas due to their high density. This study conducts a comparative life cycle assessment of two commonly used residential heating systems in Tehran: the Central Boiler Room (CBR) and the wall-hung boiler (WHB). Using OpenLCA (version 1.10) software and the Ecoinvent 3.7 database, the environmental impacts of natural gas consumption for both systems were evaluated across key categories, including global warming potential (GWP100), human toxicity potential, acidification potential, and terrestrial ecotoxicity potential. The analysis revealed that the environmental impacts of the CBR were consistently higher than those of the WHB, with average differences of 12% for all impact categories. The disparity is attributed to the greater natural gas consumption, lower combustion efficiency, and higher maintenance requirements of the CBR. The study also highlights the significant contribution of pollutant emissions such as NOx, lead, and mercury to human health risks, particularly in Tehran's urban context, where air quality is a critical concern. While the focus of the research was on the operational phase of the systems, construction and installation factors, such as energy use for pumping and piping, were also considered for the CBR. Given Tehran's climatic and geographic constraints, renewable technologies such as solar or geothermal energy were not included, as they are neither conventional nor widely feasible. The findings suggest that the WHB is a more sustainable heating option for Tehran, offering reduced environmental impacts and operational advantages. This study provides valuable insights for policymakers and stakeholders aiming to optimize residential heating solutions in urban areas.