Quantitative Study On The Implicit Environmental Impacts Assessment Of Construction Projects

Along with the process of constructing the resource-conserving and environment-friendly society, there have been broad research in environmental protection, resources conservation for construction industry, but it's still difficult to make quantitative assessment on the resources consumption and environmental impact in projects construction.From the perspective of life cycle assessment, the environmental impact of construction projects can be divided into the explicit environmental impact and the implicit environmental impact, the explicit environmental impact mainly refers to the intuitive and exposed impact in utilization, and the implicit environmental impact refers to the embodied and potential impact in construction. At present, the evaluation of environmental effects about construction projects mainly assesses the explicit environmental impacts, that it can not reflect the whole life cycle impacts comprehensively and objectively. So mainly from the viewpoint of engineering management, and combining with the theory of environmental impact assessment, the thesis makes a quantitative assessment on the implicit environmental impact of construction projects.The system of environmental impact indicators was summarized on the basis of reviewing environmental impact assessment reports of various kinds of construction projects, and the quantitative assessment method for the implicit environmental impacts was established, in which includes sixteen midpoint impact indicators and three endpoint impact indicators (environmental load impact, resources consumption impact and energy consumption impact).In the part of quantitative assessment of environmental load impact (ELI), the evaluation software Building for Environmental and Economic Sustainability (BEES) that was developed by the National Institute of Standards and Technology (NIST) was chosen as inventory database of ELI. According to the life cycle assessment system of Society of Environmental Toxicology and Chemistry (SETAC), the quantitative analysis method of calculating ELI is established, in which includes four procedures, that is inventory analysis, impact category, normalization and weighted analysis. Furthermore, the thesis calculates 1m² of ELI indicator of a university refectory project in Wuhan, and then puts forward some particular advice to reduce the ELI.In the part of quantitative assessment of resources consumption impact (RCI), the quantitative method of calculating RCI indicator is established according to the life cycle assessment and equivalency factors, and equivalency factors with coal-based is determined. Moreover, the raw materials consumption and RCI indicator are quantitative evaluation through analyze several different strength grades of concrete and fly ash concrete, and also give some corresponding suggestion to reduce the RCI.In the part of quantitative assessment of energy consumption impact (ECI), the quantitative method of calculating ECI indicator is established by combining the decomposition map, integration map of construction projects and BEES software, and the quantitative calculation and analysis is carried in the refectory project. In addition, the embodied energy of several different strength grades of concrete and fly ash concrete is calculated.Green risk assessment model of construction projects is conceived based on the above environmental impact indicators. The green risk conception, risk identification, risk classification and quantitative analysis are all studied, and the green risk assessment model of construction projects is set up according to fuzzy mathematics and entropy weight method. Lastly, the results of quantitative assessment on the implicit environmental impact are drawn into a radar-graph, which can be a reference to green risk and sustainable development of construction projects.Finally, low-carbon economy and low-carbon technology is discussed, and the effect of reducing CO₂ emission through increasing the grade of concrete and selecting low carbon building materials is also analyzed in the thesis.