An Evaluation Model of Floor Area Incentive for Urban Redevelopment Projects

容積獎勵乃政府推動都市更新的重要誘因工具之一，惟目前都市更新容積獎勵之計算方式皆以固定比例方式計算，缺乏對不同區位條件作因地制宜之彈性考量。為彌補目前容積獎勵評估所需計量分析方法之不足，以及兼顧財務誘因與環境貢獻之平衡考量，本研究將以每單位容積獎勵所發揮之社會效益最大化，建立一合理的容積獎勵評估模式。假設個案之財務資料與社會效益為固定，本研究透過環境貢獻所需的獎勵社會成本最小化，以達到效益最大化之目標，於相關計畫審議時提供個案間相對合理之容積獎勵建議值。 本研究以台北市所實施的「獎勵都更實施者參與環境改善計畫」所提供之容積獎勵額度作為個案探討對象，以獎勵改善環境所需的社會成本最小化為目標函數。並以綠地公園之闢建作為環境改善之研究範圍，新闢之綠地公園對於周遭單位房價的提升當作為環境貢獻程度之量化衡量方式。 透過實例模擬發現，座落於高綠覆率之士林區都市更新案，該案提供新增綠地之環境貢獻度相對較低，環境貢獻度僅111.18%，容積獎勵額度經過環境貢獻度之加權僅從16.96%微幅增加至18.83%，顯示此容積獎勵評估模式能夠根據周遭既存綠覆面積等情況，調整該案之合理容積獎勵額度，以形成個案不同之獎勵效果。 本研究所建立之評估模式其操作方式不同於傳統之制式容積獎勵計算模式，加入了環境貢獻度的考量，使容積獎勵評估角度更多元以及彈性更大，並追求容積獎勵之效益最大化。希冀未來透過本容積獎勵評估模式所求之容積獎勵額度，達到政策推動之有效性與效率性。本研究之容積獎勵評估模式貢獻主要有三：一、透過容積獎勵評估模式可提供兼具有效性與效率性的獎勵額度；二、對於高低不同綠覆地區能有不同之獎勵效果，提供個案間相對合理之容獎額度；三、本評估模式可於改善窳陋環境計畫之審議進行時作為參考。 由於本評估模式僅透過單一目標函數進行操作，其參數以原都市更新事業計畫之財務資料為主，建議未來可建立多項目標函數以進行求解操作，同時達到社會成本最小化與環境貢獻效益最大化目標。並可進行容積獎勵項目之全盤檢視，以評估目前相關獎勵之必要性。Floor area incentive (FAI) is an important tool promoting urban redevelopment. However, ignoring the difference between areas in distinct local conditions, the existing FAI calculating methods for urban redevelopment are inflexible. To make up the deficiencies, this thesis proposes a flexible and reasonable FAI calculating approach that which maximizes the social benefits (for each FAI) while considering both financial incentives for related real estate developers and living environmental improvement for communities. Assuming that the financial information and environmental improvement benefits are given for each case, the proposed approach maximizes the efficiency (the social benefits for each FAI) by minimizing the necessary social costs (FAI) to obtain a reasonable FAI (for the case) for reference in project review. This thesis takes the "Incentives for The Developers of Urban Redevelopment to Participate in Environmental Improvement Projects ", of Taipei City as a case study. The objective is to minimize the social costs that which are necessary for promoting the developers to improve environment quality. Besides, assuming that constructing a new park can improve the environment quality, this thesis measures the environmental contribution by means of hedonic prices around the new-constructed park. Through the case study, it is found that the environmental contribution of urban redevelopment plan in the Shilin District (the high green ratio area) is relatively low of 111.18% and the FAI slightly increased from 16.96% to 18.83%. Development of the evaluation model of this thesis is different from the traditional calculated method that which has fixed FAI. By adding the environmental contribution factor to adjust the FAI, as well as greater flexibility and broader perspective, it is able to maximize the effectiveness of the FAI. Through the assessment of the future model, FAI incentives to promote the effectiveness of policy and efficiency can be better achieved. In this study, the main findings are three: First, development of an evaluation model of FAI to promote both the effectiveness and efficiency of the projects; Second, environmental contribution for high and low green cover areas are found different incentive effects and to derive relative reasonable FAI; Third, the evaluation model can be useful for "Incentives for The Developers of Urban Redevelopment to Participate in Environmental Improvement Projects" as a reference. By now the evaluation model is only a single objective function, the main parameters based on the financial data of the urban regeneration plan, it is suggested that multi-objective function could be established to solve the conflict problems in the future in order to minimize the social cost and to maximize social or environmental improvement benefits at the same time