Carbon Dioxide Emissions Of Structure System Of Wannan Dwellings Based On LCA

As global climate change is one of the hot topics of international discussion,energy conservation and emission reduction are the two indispensable parts for addressing the environment problems as well as energy issues in China.A wide variety of new structural systems have been applied in the increasing countryside residences each year.In this paper,Huizhou traditional dwellings with the regional culture characteristics were selected to investigate the design of its structural system including masonry structures,concrete frame structures,pure steel frame structures,light wood structures and timber frame structures;Assessment of life cycle carbon dioxide emissions of the proposed structural systems was conducted and the corresponding influencing factors were identified,which may be great helpful for designing low-carbon residential Construction buildings in Wannan traditional dwellings.Firstly,the typical features of the Wannan traditional dwellings and the living habits of modern people were summarized,and the building function and plan layout of residential buildings were redesigned and optimized in order to analyze the effect of energy conservation and emission reduction in different structural system on through the same architectural working plan.On the basis of that,the building materials consumption lists of these structural systems were obtained.Secondly,carbon dioxide emission of civil life cycle was calculated for the five stages of life cycle analysis(i.e.building materials production,transportation,construction and demolition,operation and recycling of building materials).On the basis of that,carbon dioxide emissions from different structures were analyzed and compared.It was found that carbon dioxide emission from building use stage was the most important,which made up the most part of total emissions(i.e.86%-95% of total emissions),followed by building materials production with 3%-16% of total emissions.The stage of building materials transportation and the stage of building construction & demolition had emissions within 2%.Carbon reduction was found in pure steel frame structure under recovery stage of building materials,which is about5% of the total life cycle carbon dioxide emissions,while it is less than 1% for other structural systems.Finally,the influence factors were analyzed and identified for the life cycle carbon dioxide emissions of the proposed structural systems.Results show that theratio level of electric steel,the technology level of building materials production,the proportion level of the high strength structure material and the recycling level of building materials were the four main items for carbon dioxide emissions in the manufacturing stage of pure steel frame structure materials.Each items under optimization of 10% could result in a decrease of 3.3%,8%,7% and 8% for carbon dioxide emissions respectively,while they were found to have little influence on other structure systems.In addition,the proportion level of the high-strength structure material had similar carbon dioxide emissions for concrete frame structures and pure steel frame structures in the stage of transportation,which can result in carbon dioxide emissions reduction of 6.5% for each optimization with 10% and it was less than 1 %for other structures.The influences of average emission level of electricity and the life level of the buildings on carbon dioxide emissions of the proposed structural systems were found to be same.The order of the six influence factors can be summarized: the average emission level of electricity and the life level of the buildings were the most significant factors,followed by technology level of building materials production and the level of high-strength structural materials,while the ratio level of electric steel and recycling levels of building materials were the two less influential factors.