Development of Evaluation Criteria for Green Roof Subsidy Program-A Case Study of New Taipei City

Due to rapid energy consumption and the greenhouse effect, not only the temperature of global environment increases gradually, but also it has caused climate changes and frequent natural disasters. Recently, governments in different countries began to promote policies of energy conservation and carbon reduction. Among various methods to save energy-consumption and to reduce carbon emission, the green roof program is adopted to increase the urban green space, and to absorb carbon dioxide in the urban areas. The United Nations Environment Program study pointed out that the green roof coverage of 70% will lead the CO2 content of the entire city reduced by 80%, and the heat island effect will completely disappear.
In this study, by using Fuzzy Delphi and AHP expert questionnaires, the key factors of the green roof subsidy targets are identified. It is found thaboth conditions of building and surrounding physical environment, and the potential contribution to the ecology of the roof planting are the most critical elements for green roof subsidy object in the urban areas.
This study concludes that the green roof subsidies in urban areas, in order to achieve the maximal public interest, subsidies program should be targeted to meet the following conditions; green roof water retention function, building cool, clean air, recreation facilities and public facilities needs, ecological island-hopping and biodiversity. Future research is suggested to consider additional environmental impact factors such as the natural geology of the area, topography, climate, and other environment factors.