A quantitative assessment of greenhouse gas (GHG) emissions from conventional and modular construction: A case of developing country

Building construction serves a vital purpose from a social and economic perspective by meeting the housing needs of society and contributing to the economic growth of a country. However, from an environmental perspective, this sector contributes negatively by releasing tons of greenhouse gas emissions (GHG) in the atmosphere, which consequently gives rise to other environmental hazards such as global warming and ozone depletion. The use of off-site modular construction practices in developed countries is increasing due to its environmental benefits over conventional cast-in-situ method. However, the environmental performance of a construction method may vary across various geographical regions, which is why environmental assessment of construction methods specific to a region is required. This study provides a calculation of GHG emissions in modular and conventional construction methods utilized in Pakistan, considering two single-family single-storey buildings with similar characteristics. The study also provides recommendations to homebuilders for the improvements in low-performance areas in both modular and conventional building methods. The results of the study show that modular building accounts for a total of 3449.73 kgCO2-equivalent GHG emissions whereas conventional building resulted in a total of 6501.91 kgCO2-equivalent GHG emissions. Modular building results in a reduction of 3052.19 kgCO2-equivalent GHG emissions (46.9%) as compared to a conventional site-built building. This implies that the modular construction method is a more environmentally viable option than conventional construction, which needs to be adopted on a large scale to reduce GHG emissions.