Development of an automated estimator of life-cycle carbon emissions for residential buildings: A case study in Nanjing, China

Abstract

Residential buildings consume a significant portion of energy and resources during the whole life-cycle phase and meanwhile discharge an enormous amount of carbon dioxide emissions, which has directly led to the aggravation of the greenhouse effect and become a great threat to the environment and human beings. To reduce the life-cycle carbon emissions from residential buildings, researchers have made many efforts to estimate the emissions accurately. Although several building-level carbon emission databases and related calculation systems have been set up in developed countries, there unluckily remains a vacancy in China. To fill in this gap, this study develops an automated estimator of life-cycle carbon emission for residential buildings entitled “Carbon Emission Estimator for Residential Buildings (CEERB)” in China. The development process was based on the life-cycle assessment (LCA) theory, standardized carbon emission calculation method, and collection and compilation of numerous carbon emission coefficients available in China. The database for storing carbon emission coefficients is based on the SQLite 3.0, and the user interface is designed with Qt 4.7. Followed by the establishment of the CEERB system, it has been exemplified in a masonry concrete residential building in Nanjing (China), demonstrating its applicability and capability in estimating the life-cycle carbon emissions of residential buildings. The results indicate that: (1) the life-cycle carbon emissions of this project were 1.7 million kg and the annual emissions per square meters were 19 kg/m2/year; (2) the O&M phase contributed the most (63%) to carbon emissions, followed by the material production (32%); (3) regarding to material embodied emissions, concrete reached roughly 44% of total material emissions, followed by the steel (20%); (4) during the construction phase, the superstructure project accounted for the most emissions (78%), primarily by tower cranes and hoist; (5) during the operation phase, electricity contributes 88.3% of emissions, followed by natural gas of 8%. Discussion and implicated policies, such as annual emission profile and impact of using recycled materials, have also been elaborated at the end of the study. Based on the proposed estimator CEERB, contractors can be more efficient and convenient to evaluate carbon emissions at the early stage of a project and make appropriate carbon management plans to reduce emissions when facing stricter environment policies in the future.