Emission Of CO₂ And PM2.5 Of Building Materialization Stage With Uncertainty Analysis

CO2 and PM2.5 will cause global warming and particulate pollutions.For the construction sector,its CO2 emissions account for about 25%of the world's total emissions,and the dust generated by construction sites accounts for about 32.1%of the total urban dust.Therefore,it is of great significance to inveterate the emission of CO2 and PM2.5 in the process of building production.Through literature review of environmental impact of buildings,the author finds that as the largest emission stage in the life cycle of buildings,the use stage has been fully studied.However,when taking whole life cycle into account,the materialization stage(including all pre-activities before the use of the building)discharged 20%-30%of the total polutions within 1-3 years,the emissions of use stage within 50 service years accounts for 70%-80%,thus,the annual emissions of materialization stage will exceed that of use stage.In the past,there were few studies on the environment impact of materialization stage.Therefore,this paper studies the emission of CO2 and PM2.5 in the materialization stage.For the CO2 quantitative model,it is calculated and analyzed according to the category of material and energy in the past.However,such results do not match the design process with component as the design object,which makes it difficult for designers to conduct emission reduction design according to such results.Therefore,according to the quota of engineering budget,the construction project will be decomposed according to unit project,division project,sub project and unit process.For each unit process,CO2 is quantified according to the LCA method.Combining with project budget,the CO2 emission of each sub project,division project,unit project and the whole building in the phase of materialization is obtained respectively.In the PM2.5 quantitative model,the dust of the construction site was not considered in the past.In this paper,excepting the embodied PM2.5 emissions generated by the dust,the PM2.5 net concentration generated by construction activities in the construction site is also calculated.At the same time,because of the method of LCA used in the quantitative process is a probabilistic environmental impact evaluation and it has uncertainties.Therefore,this paper uses the method of DQI and scenario analysis to quantify the data uncertainty and scenario uncertainty respectively.Finally,combined with the actual project case,the CO2 and PM2.5 emissions and their uncertainties are calculated and analyzed based on the above models.Combined with the construction schedule,the emission of CO2 and PM2.5 and the change of PM2.5concentration in construction site with time are analyzed.According to the quantitative results,during the materialization stage,the key points of emission reduction for CO2 and PM2.5 are the concrete and reinforced concrete works in civil engineering,and the first three emission reduction processes that need to be focused are diameter less than 10 cast-in-place member reinforced bar,straight wall,diameter less than 20 cast-in-place member reinforced bar and straight wall,diameter less than 10 cast-in-place member reinforced bar,plate.The relatively dense phase of CO2 emission is the main structure construction and initial decoration stage.The relatively dense phase of PM2.5 emission is the foundation excavation stage,and the maximum PM2.5 net concentration generated by the construction activities reaches 907.37?g/m3.