Study On Technology And Economy Of Water-Saving About Green Building Community

The development of water-saving in green building is according with the national strategic policy of building a resources-conserving and environment-friendly society and it is beneficial to saving energy, protecting environment, and harmonious development of constructions and ecosystem. According to the lack of technical support system for water-saving indices in newly issued evaluation standard for green building and since green building develop just beginning, green building technical system was researched based on system analysis and summary of water-saving techniques and engineering practices. Aiming at the long-existing problem of unsuitable design load, low operation efficiency and unstable effluent in many intermediate water systems (IWS), treatment of different use reclaimed water by combinational technique of artificial wetland was experimentally studied. In view of incomprehension to incremental cost and benefit of green building, comprehensive benefit in full life cycle and incremental cost of water-saving project in green building were systematically researched. The conclusions are as follows:①Based on investigation and analysis of water-saving techniques in cities and structures, water saving technology system was constructed, including water supply system, reclaimed water treatment and utilization system, rainoff collection and use system, water quality control system for landscape water body using unconventional water resources, and safety guarantee system for unconventional water resources transmission and distribution. The water-saving techniques were improved to suit for green building and were demonstrated in a green building district in western China, which realizes 37.8% (202 kiloton) municipal water saved, 30.4% (146kiloton) unconventional water utilized, and could offer technological support for buildings achieved requirements of evaluation standard for green building.②Experimental study on the efficacy of superior drainage treated by combinational technique of coagulation sedimentation and artificial wetland was launched. The results showed that: the regression equations relating to effluent BOD5, temperature, load and addition dosage is: BOD5 = 1190NA-0.32t +12.2. The optimization model of investment is: According to the model, reasonable scale of IWS can be determined. The results offered technological support for reclaimed water treatment, which regards superior drainage as the source, has great variation in water quality and quantity, and is purified by combinational technique of coagulation sedimentation and artificial wetland.③Experimental study on the efficacy of superior drainage treated by combinational technique of contact oxidation and artificial wetland was launched. The results showed that: TN is the restrictive index of the technique treatment effect. To meet the requirements of Water Quality Standard for Scenic Environment Use, the peak hydraulic load of artificial wetland is 0.50m/d in high temperature(30℃-36℃), and 0.33m/d in low temperature(8℃-12℃), and the superior drainage must pre-treated by contact oxidation on load of 0.72KgBOD5/m3·d. The load ratio of the peak hydraulic under two temperature conditions is 3∶2. According to the results, reasonable scale of IWS can be determined.④Based on concepts of full life cycle and present situation of water-saving in green building, calculation model of comprehensive benefit in full life cycle for green building water-saving project (including direct benefit of water-saving, economical and social benefits, and life cycle cost) was first put forward and used in this study. Monte carlo simulation was adopted on analysis the uncertainties of full life cycle and minimize it, and then, cost function and parameter variable system was established based on monte carlo simulation, and was analysed by crystal ball software. The system was applied to a green building district in western China, and the results showed that green building got remarkable comprehensive benefit. The comprehensive benefit in full life cycle was 47.132 million yuan, the direct incremental cost was 18.586 million yuan, and the ratio of benefit to cost was 2.5:1.The researchs of technical system and comprehensive benefit in full life cycle of green building have important realistic meanings. It will offer technological support for water-saving, will provide economic theory for decision making in water-saving scheme selection, and will lay a foundation of further study on green building water-saving.