During recent decades, urban development and growth usually happened in ways contradictory to the concept of sustainable development, although this concept is theoretically agreed on in many of the relevant policies. In particular, suburbanization or development in Greenfield sites produced spatially diffused and functionally segregated settlement structures around cities, this continuing trend increased pressures on the environment such as climate change and problems due to carbon dioxide. As changes in existing urban structures and new urban development are currently occurring in parallel, we need new planning system to direct both towards sustainable solutions, to reduce environmental impacts such as climate changes in city or town.
Recently, the term Green-city or Eco-city has so far been used mainly by movements which aiming to realize new solutions as alternatives to current developments. As a new urban system or a development model, the Low-Carbon Green City can be a solution for sustainable urban development to address climate change, which is the greatest environmental challenge facing the world. With these considerations, this study was used to find the model to evaluate existing planing system toward the Low-Carbon Green City, which is to minimize use of land, energy, and materials in urban system and the impairment of the natural environments.
The objective of this paper is to develop the evaluation model for planning system of Low-Carbon Green City on climate change and apply this model in current urban development project in greenfield sites. To achieve these objectives, this study analyzed relative importance and the influence of planning elements in Low-Carbon Green City using survey method of AHP(Analytic Hierarchy Process) and QFD(Quality Function Deployment) for development and application of the evaluation model. The planning elements as evaluation factors are based on the spatial restructuring for qualities of urban form and the physical restructuring of the fabric and metabolism at various scale of urban system.
The evaluation model is developed by the following processes:
First, the evaluation criteria for classifying major components in Low-Carbon Green City were initially identified through justification process with review of literature and expert survey, after broken down into 2 categories, and then further divided into each 5 items on quality of spaces(Q; Q1:accessibility, Q2:efficiency, Q3:viability, Q4:security, and Q5:amenity) and planning elements(G; G1:land-use, G2:green transport, G3:green space, G4:resource management, G5:energy efficiency) with 17 factors accompanying with hierarchical structure.
Second, the relative weights of the evaluation criteria were derived by employing AHP, which aims to understand the co-operative relationship or effects between items (Q, G) and analyze the relative importance of planning elements with relation to quality of spaces.
Third, the influence on planning elements (G) in relation to quality of spaces (Q) was analyzed by QFD. In particular, the influence was identified by the consideration of urban location type such as Greenfield and Brownfield.
Fourth, overall influence weight reflected by the relative weights of Q and G is analysed to apply especially for urban development project in greenfield site. The major results were summarized based on the following relative importance among 17 factors in five aspects(planning elements): 1st G3-2(integrated green space and bio-climatic comfort; 12.51%), 2nd G2-2(public transport oriented urban structure; 8.93%), 3rd G4-3(minimize the volume of waste and maximize recyclability of materials; 8.17%) etc.
The developed evaluation model is applied for the Hakha urban development project which is located at greenfield site in Daejoen, Korea):
First, the development process of city planning for the Hakha district from master plan(A; 1995) at initial stage to development plan(B; 2006) and green town plan(C; 2010) were reviewed according to the evaluation criteria based on Q and G.
Second, the relative weights of the evaluation criteria based on the Hakha's city plans(A,B,C) were much higher in Q1 and Q3 than in Q4 and Q5, which was the opposite direction comparing to the evaluation model. On the other hand, the planning elements(G) in relation with Q2(efficiency) in plan C(green town plan) were perfectly followed the evaluation model.
Third, overall influence weight applied to the Hakha's city plans were summarized based on the following relative importance among 17 factors in five aspects(planning elements): 1st G3-2(integrated green space and bio-climatic comfort; 16.18%), 2nd G5-2(energy saving building; 12.71%), 3rd G1-4(public space with accessibility; 12.10%) etc. Based on these results, Hakha's city plan was mainly focused on G5(30.07%) and G3(23.51%).