Comparative Analyses for Green Roof Life Cycle and Cost-efficiency Assessments by Varied Methods

• Main Authors: Chen, Pin-Wei, 陳品維
• Other Authors: Kao, Jehng-Jung
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/28013011252480882757

碩士 === 國立交通大學 === 環境工程系所 === 104 === Since green roofs (GRs) can offer various benefits, domestic and foreign cities had widely applied GRs. This research group had also developed several light and hollow ventilated green roofs (LHVGRs) and DIY green roofs (DGRs). However, so far no comprehensive analysis is available for comparing these GRs. This study thus will implement life cycle assessment (LCA) and cost-benefit analyses for comparing the conventional roof (CR), GR, LHVGR, and DGR. There exist different LCA midpoint and endpoint methods that may give different impact valuations and may subsequently affect the final assessment. This study thus will evaluate the results obtained from varied methods and analyze their applicability for comparing life cycle environmental impacts of different green roofs. Personnel and city-wide costs and benefits of different green roofs will be also estimated. A comprehensive aggregative analysis based on aforementioned results will be implemented to compare the green roofs. This study selects Impact 2002+, BEES+ and CML-IA(Baseline) three midpoint methods to compare and analyze their results for assessing various GRs. Among Global warming assessment results, DGR-100 has greatest impact evaluated by all three methods. LHVGR ranks the worst for Natural resource depletion, while GR does not perform well for Ozone layer depletion and Ecotoxicity. LHVGR, DGR-100 and DGR-64 all have significant impacts on Eutrophication and Acidification. The Human cancer toxicity impacts of LHVGR,DGR-100 and DGR-64 are similar. Two endpoint methods of Impact 2002+ and EPS 2000 are also evaluated. The results show that Resources and Abiotic Stock Resource respectively contribute 50% and 75% of the endpoint scores, because green roofs use several artificial materials that increase the impacts on Resources and Abiotic Stock Resource. Therefore, the effective approach for reducing the impacts from green roofs, is to avoid using artificial materials. Personnel and city-wide cost and benefit assessments, in terms of the average annual cost of forty years, are also implemented. GR have higher initial cost than LHVGR. With the green cover ratio policy, GRs can replace grass investment for about 9.6 to 12.6NT$/m2. The carbon emission reduction is about 32.78 kiloton CO2eq/yr. LHVGR performs the best in energy saving, saving approximately 4.80~5.18 kWh/m2/year. In addition, LHVGR also performs the best in rainwater recovery.