現代都市建築密度高，人工不透水鋪面多，再加上冷氣、鍋爐、汽機車排放大量廢熱，使得市中心的溫度居高不下，形成嚴重的都市熱島效應（urban heat island effect）。目前許多國家已有針對都市熱島效應減緩設立的綠建築評估規範，例如台灣的EEWH以及日本的CASBEE，規範內容主要是評估建築規劃案是否有採用降溫節能的手法，比如引進自然通風、提升植栽面積、使用高反照率的屋頂材料等等，最後根據各項表現給予一個總分，用以評鑑其減緩都市熱島效應效果之優劣。然而，評分只能讓設計者看出好壞，無法預測環境內溫度、通風、熱舒適度之變化，因此本研究的目標是建立都市戶外熱環境的預估方法，呈現設計案增溫與通風的具體數據，供建築設計者與評鑑人員參考之用。
本研究先是針對台南市兩個建築型態不同的社區進行溫濕度之實際測量，了解都市熱環境的特性，並掌握影響溫度、濕度、風速的重要因子；接著，再利用微氣候預測電腦模型ENVI-met針對這些因子進行敏感度測試，藉以釐清因子與氣溫、平均輻射溫度（mean radiant temperature）、生理等效溫度（physiological equivalent temperature）之相關性；再來將影響重大的因子設定為模型參數，混和各項參數建立模型，用ENVI-met進行模擬。由於模擬耗時，為了減少實驗次數，採用田口方法，將模型數量控制在27個，既可減少耗費的時間亦能確保實驗維持精準度。最後，針對模擬結果進行數據分析，推導出下列三條預測式，用以預測下列三項指標：
1. 評估基地內空氣溫度增加幅度
2. 評估基地內生理等效溫度
3. 評估基地周邊通風情形
本研究期望上述預測方法能夠讓設計者與從業人員在短時間內評估一建築設計案可能造成的增溫情形、戶外人員舒適度、通風效益。只要代入參數，即可初步掌握基地內的熱環境，評估舒適與否。

This study aims to establish a prognostic equation for assessing the thermal environment of urban communities. At first, actual measurements were carried out in two types of communities in Tainan, Taiwan to determine the difference between their temperature and humidity; then, several microclimatic factors were selected and tested in ENVI-met, a computer-based prognostic model, through a series of sensitivity measurements; finally, seven significant factors were chosen and each was given three levels of design. Different factors are then incorporated into twenty-seven composite models in ENVI-met; by running simulations and analyzing the results, the significance of each factor can be determined. In the end, three prognostic equations were established to assess the mitigation of the urban heat island effect, thermal comfort, and natural ventilation.

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