城巿綠屋頂成本效益評估及懸空式綠屋頂設計與模式模擬

Abstract

綠屋頂具有多種顯著環境效益，故國際上正積極推廣中，國内亦正在起步中，唯目前甚 少有研究評估其在國内城市推廣的成本效益，且傳統式綠屋頂由於一些限制使大眾接受度不見 得高，本研究因而將建立一套方法評估國内城市推廣綠屋頂的成本效益，且將開發數種不同型 式的懸空式綠屋頂及建立模式模擬其隔熱降溫節能效益。城市綠屋頂的效益將以一個城市為案 例，依據熱傳導係數及建築能耗模式模擬結果評估節能減碳效益，減碳部分則除了節能所造成 的減碳效益以外，亦依植物固碳能力估算城市綠屋頂之減碳效益，截水效益則依據之前的研究 成果推估，空污減量則依據乾沉降、過濾及葉面吸收等機制推估其可減少的空氣污染量。懸空 式綠屋頂則預計設計開發數種不同型式，以期改善綠屋頂的建置便利性、重量、價格、防水要求、 維護彈性與接受度，且將建置模場及實際量測各種參數及用紅外線熱像儀拍攝其表面溫度，並據以估 算其節能效益，且將進一步建立模式模擬其屋頂降溫效能，亦將與傳統綠屋頂進行成本效益比較，所 得成果預期可作為國内各城市推廣綠屋頂相關規劃決策之重要參考依據。

Green roof technology has various environmental benefits and is widely adopted by many countries worldwide. However, the method to evaluate the cost-benefit of green roofs for a domestic city is so far not available. Furthermore, the conventional type of green roofs may not be accepted by the general public due to its difficulties in installation, maintenance, and waterproof requirement. This study is thus initiated to develop a systematic method to evaluate the cost-benefit of green roofs for a local city and design several hollow types of green roofs. Equations or models will be established for estimating the thermal reduction and energy saving capabilities of the hollow green roofs too. A case study for a local city will be implemented for estimating possible energy saving, GHG emission reduction, runoff reduction, and air pollutant removal benefits of green roofs. A one-dimensional heat flux equation and a building energy consumption simulation model will be used to determine the energy saving benefit. Other than the energy saving, the GHG emission reduction is also estimated based on the carbon sequestration capability of the vegetation cover of green roofs. Runoff reduction ability is computed based on the equations developed in one of our previous research projects. Air pollutant removal is quantified based on dry deposition, filtration, and leave absorption mechanisms. Several different types of hollow green roofs are to be designed and installed according to the following essential design criteria: installation difficulty, weight, cost, waterproof requirement, flexibility, and acceptability. Various parameters will be monitored for installed hollow green roofs, including the spatial surface temperature by an infrared themocamera. Energy saving by the hollow green roofs will be estimated based on monitored data, and equations or models will be established to simulate the thermal reduction. Comparisons with a conventional green roof and a general roof are also to be made for their costs and benefits. The results obtained in this study is expected to assist local city governments in planning and making appropriate related decisions and policies for developing green roofs.