綠屋頂土壤熱通量之監測與模擬

Abstract

隨著氣候變遷與都市熱島效應日益嚴重，建築能源消耗量也逐漸上升。為了能夠有效減緩此現象以達到永續環境的目標，綠屋頂阻隔熱能的效果也備受重視。 本研究之主要目標為了解在台北的氣候下綠屋頂的隔熱效果，因此於研究中選取三個不同維護管理程度(零維護、低維護、高維護)以及植被的綠屋頂進行溫度及熱通量的實測。此外也使用解析解以及半階微分法(half-order time derivative method)與土壤熱通量實測值進行比較，評估模式的準確度。 在模擬部分，半階微分法與實測值近似，其推估的熱通量可有效作為綠屋頂的實測熱通量，但是解析解則無法有效模擬且維護程度越高其模擬結果越差。 在監測部分，研究結果顯示葉面積指數(leaf area index)越大的綠屋頂，其土壤表面溫度相對於水泥表面溫度可降低最多。此外，在綠屋頂底部土壤熱通量方面，除了零維護綠屋頂在白天仍有熱通量進入室內，其餘綠屋頂的熱通量皆為整日離開室內。 研究的最後進行成本效益評估，將綠屋頂的初始成本與維護成本納入計算，加入各綠屋頂所帶來的節電效益進行比較。在利用實驗資料及成本資料進行計算後，最後的結果發現在三個綠屋頂中，零維護綠屋頂有最低成本。

With the increasing severity of the urban heat island effect and climate change, the energy consumption of buildings is also gradually increasing. To effectively mitigate this phenomenon and achieve sustainable environmental goals, the thermal insulation effect of green roofs is highly valued. The main objective of this study is to investigate the thermal performance of green roofs in the climate of Taipei. For this purpose, three green roofs with different maintenance levels (zero maintenance, low maintenance, high maintenance) and vegetation were selected for temperature and heat flux measurements. Additionally, analytical solutions and half-order time derivative method were employed and compared with measured soil heat flux values to evaluate the accuracy of the models. In the simulation part, half-order time derivative method approximates well with the measured values, and its estimated heat flux can effectively serve as the measured heat flux for green roofs. However, the analytical solution cannot simulate effectively, and the higher the maintenance level, the poorer the simulation results. In the monitoring part, the research results show that green roofs with a higher leaf area index can significantly reduce soil surface temperature compared to cement surface temperature. Furthermore, about soil heat flux at the bottom of the green roofs, except for zero-maintenance green roof which still has heat flux entering indoors during the daytime, the heat flux for the other green roofs is predominantly leaving the indoors throughout the day. Lastly, a cost-benefit evaluation was conducted, considering the initial cost and maintenance cost of green roofs, along with the energy-saving benefits provided by each green roof. After performing calculations using experimental data and cost data, the results revealed that zero-maintenance green roof had the lowest cost of three green roofs.