Empirical Analysis On Ecological Improvement In One Construction Engineering Based On Building Life Cycle Carbon Emission Assessment

Evidence shows that carbon dioxide emission is one of the primary cause of global warming,the issue of energy conservation and emission reduction has received more attention.Construction industry is responsible for over one third of global carbon emissions.Therefore,it has some realistic significance to do researches on quantum mechanical calculation of building life cycle carbon emission and putting forword ecological improvement measures based on the estimated emission data.From the view of building life cycle carbon emission,based on life cycle assessment theory framework,the system boundary of building carbon emission is determined and is divided into five phases which include building material production,building material transportation,constcuction and installation,operation and maintenance,as well as dismantlement and disposal phase.Life cycle inventory analysis is implemented in each phase separately.Based on data collection and sorting of common carbon factor database,building life cycle carbon emission calculating model is established by applying carbon fator calculating measure.In this paper,an expansion project of office building in Guangzhou is chosen as an empirical case to study the carbon emissions in different building life cycle phases.The results show that the life cycle carbon emission of this building is 153572.85 tons and its life cycle carbon intensity is 113.48 kg_CO2/a·m2.Operation and maintenance phase has the greatest proportion of carbon emission which accounts for 84.14% of the total emission,followed by material production phase which is 13.38%,while the sum of rest three phases only account for 2.47%.Operation and maintenance as well as material production phase are potential for carbon reduction,which should be paid more atttention.In material production phase,the carbon emissions per unit area in repaired and reinforced part is 149.00 kg_CO2/m2,while in new constructed part is 901.76 kg_CO2/m2.Through suitable repair and reinforcement of old structures and building can reduce original material input so that can decrease carbon emissions in material production phase.In operation and maintenance phase,air conditioning system,electric equipments and lighting facilities are the main source of carbon emissions,made up 38.71%,24.88% and 24.35% of total emissions separately.According to the features of carbon emissions in different life cycle phases,the following ecological improvement measures can be applied.It is suggested to use recyclable materials and increase material yield rate in building material production phase;in building material transportation phase,we should select local material and chose the low-carbon modes of transportation;in building operation and maintenance phase,increasing the thickness of wall insulating layer,improving thermal performance of external windows,setting suitable sunshade,using energy-saving lamps and lantern,prolonging the service life of building can be applied.The life cycle carbon emission of improved building reduces to 143071.75 tons,life cycle carbon intensity decreses to 88.10 kg_CO2/a·m2,carbon reduction is 22.37%.The calculating model of building life cycle carbon emission established in this paper and ecological improved results can provide some reference for other office building life cycle carbon emission researches.