Research On Staged Emission Reduction Strategy Of Construction Industry Based On Measurement Of Life Cycle Carbon Emissions

As a pillar industry of the national economy,the construction industry has played a vital role in China's economic and social development,but at the same time,the problems of resource consumption and environmental pollution have become increasingly prominent.According to IPCC statistics,the construction industry accounts for 40% of the world's energy consumption,and its carbon emissions account for 36% of global carbon emissions.China's construction industry's total carbon emissions account for 28%-34% of total carbon emissions,becoming the main source of carbon emissions.Therefore,analyzing and measuring the main sources of carbon emissions in the construction industry,identifying the driving factors of each stage of carbon emissions,it is of great theoretical and practical significance to propose a phased emission reduction strategy for the construction industry.Firstly,the life cycle analysis method was used to establish a carbon emission inventory from the four stages of building materials preparation,construction,operation and demolition.On the basis of conventional emissions,the negative carbon emissions from building materials recycling and construction waste recycling in the construction industry were supplemented,and the life cycle carbon emissions of the construction industry were measured and analyzed.Secondly,using the LMDI factor decomposition method,a life-cycle-based decomposition model of carbon emissions in the construction industry was constructed,and the contribution of factors such as carbonemission coefficient,energy(building materials)consumption structure,energy(building materials)consumption intensity,labor productivity,construction scale and population density to changes of carbon emissions in different stages of the construction industry were analyzed to identify key positive and negative factors.Finally,the underlying causes of changes in the carbon emissions of the construction industry were explored,and based on this,the following conclusions were drawn.(1)The carbon emissions of construction industry mainly come from the building materials preparation stage and operation stage,which account for 70%and 20% of the total carbon emissions respectively,among them,the carbon emissions in the building materials preparation stage mainly come from two high-energy-consumption building materials,cement and steel.Therefore,the key to achieving energy-saving and emission reduction of construction industry is to optimize the structure of the building materials and improve the production process of cement and steel.(2)The recycling of building materials and construction waste in the construction industry offsets the carbon emissions of building materials preparation stage and demolition stage to a certain extent,and plays a role in reducing the carbon emissions of the construction industry.Therefore,the recovery rate of building materials should be increased,technical input should be increased,construction waste should be reduced,and the recovery rate of construction waste should be improved.(3)The phased-based LMDI year-to-year factor decomposition results show that the changes in carbon emissions of construction industry are mainly affected by changes in carbon emissions during the building materials preparation stage and operation stage,and their contribution amounts to more than 99%.(4)The key factors driving the growth of carbon emissions in constructionindustry are construction scale and labor productivity,among them,the contribution of labor productivity is gradually strengthening,and population density is a key factor in inhibiting carbon emissions growth.According to the above research conclusions,the phased emission reduction strategy of the construction industry,such as vigorously developing low-carbon buildings,improving the recovery efficiency of building resources,optimizing the structure of building materials,and increasing investment in technology research and development,was proposed to achieve a win-win situation in the economic growth of the construction industry and environmental social responsibility.