都市永續性的衡量通常以永續發展定義為基礎，而評量永續發展的測量尺度通常以列舉永續發展原則為主，對執行上之定義及落實層面的討論則較少有一致性，這個理由造成落實永續發展原則的疑慮，本文以建構在永續性軌跡評估上的策略建議，直接挑戰永續發展在執行面的一致性。生態足跡模型為William E. Rees與Mathis Wackernagel於1994年提出之評估永續發展工具，該模型的特色在於利用計算特定區域人口消費行為轉換為每人消耗之土地面積，討論消費行為是否超過每人應得之生態標竿，並對該地造成生態上不可回復的損害。儘管生態足跡分析在人類消費行為與生態生產力土地分類及利用單一資料值判定是否超過永續發展的生態容受上尚存爭議，但站在維持資源存量不變的強永續性定義下，生態足跡分析的確可以提供政策制定之充分資料，長期間之觀察並可直接衡量永續性軌跡的脈絡。建構在生態足跡理論之基礎下，本文以台中都會區作為研究物件，計算台中都會區自1988年至1997年間之生態足跡、生態標竿及生態赤字，以此資料值分析台中都會區10年來永續性軌跡的變化。本文的第一部份討論都市永續性的定義及落實政策執行面一致的永續性策略；第二部份說明生態足跡分析與都市永續性之關係，並運用生態足跡分析模型修正都市永續性的評估結果；第三部份為台中都會區10年來生態足跡、生態標竿及生態赤字的計算結果；第四部份衡量台中都會區10年來永續性軌跡變化之情形；最後一部份則為結語。
The measurement of urban sustainability has always been based on the definition of sustainable development and the evaluation of sustainability has usually only listed sustainable development principles without further elaboration. Furthermore, the exploration regarding the implementation of sustainable development is lack of consistency, which casts doubts on the feasibility of sustainable development principles. Based on the measurement of urban sustainability, this article proposes policy recommendations to challenge the consistency of implementing sustainable development. The Ecological Footprint (EF) analysis was proposed by William E. Rees and Mathis Wackernagel in 1994. The characteristic of the EF analysis is to calculate average consumption behavior in a certain area and to transform the consumption behavior to land areas per person. By doing so, land areas consumed by each person can be calculated to see whether the land areas used exceed the average land areas available to each person (i.e. ecological benchmark) and whether they have caused irreversible damages to the environment. Although there exists debates regarding the land classification system and the single data indicator, the EF analysis still provides useful insights to help proposing policy strategies based on the strong sustainability definition. A long-term observation of the EF analysis can provide further the trend of sustainability of a certain area. Using the EF analysis as the theoretical foundation, this article calculates the ecological footprint, ecological benchmark, and ecological deficit in Taichung metropolitan area from 1988 to 1997. Section 1 discusses the definition of urban sustainability, and strategies for implementation. Section 2 explores the relationships between the EF analysis and urban sustainability and uses the EF analysis to measure urban sustainability. Section 3 is the result of the ecological footprint, ecological benchmark, and ecological deficit in Taichung metropolitan area. Section 4 examines the sustainability trend from 1988 to 1997. The last section is the conclusion.
