Civil Engineering Infrastructures Journal, 50(1): 191 – 206, June 2017 Print ISSN: 2322-2093; Online ISSN: 2423-6691 DOI: 10.7508/ceij.2017.01.012 Technical Note Estimation and Evaluation of Greenhouse Gas Emissions during the Life-Cycle of Wastewater Pipelines: Case Study of Tehran, Iran Roghani, B. 1 , Tabesh, M. 2* , Amrollahi, M.S. 3 and Venkatesh, G. 4 1 Ph.D. Candidate, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran. 2 Professor, Centre of Excellence for Engineering and Management of Civil Infrastructures, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran. 3 M.Sc. Graduate Student, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran. 4 Senior Lecturer, Department of Engineering and Chemical Sciences, Faculty of Health, Science and Technology, Karlstad University, Karlstad, Sweden. Received: 17 Sep. 2016; Revised: 26 Apr. 2017; Accepted: 10 May 2017 ABSTRACT: Climate change occasioned by the accumulation of greenhouse gases (GHGs) is now widely accepted as an issue which mankind needs to address. The starting point is necessarily the determination of all the sources of emissions during the life-cycles of the studied components. Post-calculation, the results ought to be presented to decision-makers in a clear manner so as to provide the basis on which corrective actions could be considered. This paper calculates the GHGs emissions during the life-cycle of wastewater pipelines and introduces a different approach to communicate information about GHGs released, to decision-makers. Different diameters of concrete and high-density polyethylene (HDPE) wastewater pipes are compared in a case study. Results show that the total CO2-equivalent (CO2-eq) emissions attributed to concrete pipes are greater than HDPE pipes. Hence, the equivalent bio-productive area of forest required to sequester the CO2 (the major GHG) and its corresponding costs will be greater for the former. Keywords: CO2-eq Emissions, Concrete Pipes, Ecological Footprint, HDPE Pipes, LCA, Wastewater Collection Networks. INTRODUCTION Greenhouse gas (GHG) emissions attributed to the combustion of fossil fuels have been instrumental in bringing the world to the juncture it finds itself in, with regard to climate change and associated challenges. Of late, the environmental aspect of sustainability has been factored into decision- making in the infrastructure sector, in Tehran (Iran) (RPCT, 2012). According to a World Bank report, the air pollution index was equal to 282 ‘unhealthy’ days in year-2000 in Tehran (World Bank, 2005). Every country is expected to formulate its own strategies and targets for the mitigation of global warming. * Corresponding author E-mail: mtabesh@ut.ac.ir 191