- 學位論文
通風遮陽板應用於建築外牆的節能模擬分析
Numerical Analysis of Ventilated Shading Plates for Energy Conservation in Buildings
摘要
台灣的新式建築或老舊建築的改建，其裝設的遮陽板與隔熱方式多缺乏深入的研究與探討，因此本論文旨在加入考慮台灣的氣候條件、並配合建築的方位，對建築物西曬牆裝設通風遮陽板之後的節能效益作定性且定量的研究。本研究使用商用計算流體力學(CFD)軟體FLUENT作為數值模擬分析的工具，穩態模擬的結果顯示厚度0.25m的西曬牆在裝設遮陽板之後能減少41%的入熱量。動態模擬加入考慮熱質量(Thermal mass)的蓄熱效應，0.25m不裝設遮陽板的西曬牆時滯為4.3個小時，在裝設遮陽板之後，時滯增加為7個小時，一天之內的最大入熱量可減少46%，內壁最高溫下降2度。裝設遮陽板之後，間隙內形成的自然對流比不流動的空氣層能減少西曬牆21%的入熱量，而使用主動式通風將流速提升至自然對流的1.7倍時僅減少10%的入熱量，因此使用自然對流通風在建築整體節能效益上更具有優勢。本文使用等效熱阻的概念將通風遮陽板的節能效益視為一種虛擬的隔熱材料，西曬牆加裝通風遮陽板之後總熱阻上升了70%，相對來說遮陽板所形成的遮陽隔熱效果相當顯著，因此可以達到減少41%入熱量的節能效益。本文在最後使用台大新能源中心建造的低能屋作為等效熱阻概念的驗證對象。並於七月十三號至十五號得到與量測數據非常接近的模擬結果，這顯示本文成功地將等效熱阻的概念用於評估建築耗能之中。模擬結果也顯示裝設遮陽板之後，低能屋的立面牆熱傳透率小於0.15W/m2K，而德國的建築法規明定低耗能的建築立面牆熱傳透率應達到0.3W/m2K，由此可見，台大新能源中心所建造的第一代低能屋已達到甚至比規範更好的外牆隔熱能力。
並列摘要
This thesis aims to conduct the qualitative and quantitative research for the energy conservation in building by using the ventilated shading plate on the western external walls. The simulations were conducted using the commercial, well-known, general-purpose CFD code, FLUENT. The steady-state simulation results show that the western external wall with thickness 0.25m can reduce 41% heat gain by using the ventilated sun shading plate. The dynamic simulations add the thermal storage effect of the building thermal mass, and the results show that the time lag of the western external wall with thickness 0.25m is 4.3 hours, when installing the ventilated sun shading plate, the time lag is increased to 7 hours, and the maximum heat gain can be reduced 46% within one day. In this study, we use the equivalent thermal resistance concept to evaluate the energy conservation performance of the ventilated shading plate, the simulation results show that the total resistance of the western external wall increase 70% by using the ventilated shading plate. Finally, We use the low-energy house which is built by the New Energy Center in NTU as the validation object of the equivalent thermal resistance concept, and good agreement between the measured data and the simulation results was obtained. The results also show that after the installation of ventilated shading plate, the U-value of the low energy house external wall is less than 0.15W/m2K, while Germany's building energy conservation standards specify that the U-value of the low energy consumption buildings external wall should less than 0.3W/m2K, as a result, the low-energy house has reached the low energy building standard.