Evaluating carbon emissions of construction and demolition waste in building energy retrofit projects

Building energy retrofit (BER) is one of the priority tasks of China's '14th Five-Year Building Energy Efficiency and Green Building Development Plan'. The number of BER projects has dramatically increased in recent years in China, studies related to the management of construction and demolition waste (CDW) from BER projects have not kept pace. There is a need for more related studies, particularly for evaluating and mitigating the environ-mental impact of CDW from BER projects. This study aims to evaluate and mitigate carbon emissions from CDW of BER projects using a system dynamics (SD) approach through a case study BER project in the urban area of China. The SD model developed for this study includes sub-models for evaluating carbon emissions from the dismantlement of old components and the retrofit construction. Three scenarios were developed and the scenario analysis results reveal that the carbon emissions of CDW from the dismantlement of the old components account for higher carbon emissions than retrofit construction. Improving the inert waste recycling rate from 50% to 90% could save 2034.43 kg CO2 eq carbon emissions. Reducing 50% of CDW in BER construction could save 7673.06 kg CO2 eq carbon emissions. Improving WTE incineration rate from 50% to 100% could save another 50.53% of carbon emissions from the combustible waste. The SD simulation model provides a dynamic and non-linear scenario analysis platform for decision-makers to analyze the carbon emissions for managing CDW from BER projects.