中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
面對全球暖化的威脅，減碳已成為世界共同倡議之方向。台灣在此潮流下，也積極朝建構永續宜居環境，提升智慧綠色科技應用之方向努力，希望在減低建築物能量消耗的同時，也能兼顧宜居空間的基本需求。而室內通風不僅影響空間的溫度，也關係建物使用者的健康。如何有效導入外部風場，利用自然通風機制減少建物空調能源之消耗或提供健康之居住環境是目前使用維護上之重要議題。而建築物內氣流環境與空氣品質之好壞常取決於室內之通風效果。台灣地處亞熱帶氣候區，全年有近半年的時間可以藉由自然通風的方式進行室內外空氣交換，以達到調節室內空氣溫度與品質之目的。
而營建工程隨著新技術及新工法之發展，工程內容之質量與多樣性劇增，建物資訊越趨複雜。營建業者與學者不斷使用新的資訊科技(Information Technology)，以提供生命週期各階段團隊更精確及實用之建物資訊，朝向建物生命週期資訊整合及智慧管理之目標邁進。而建築資訊模型(Building Information Modeling, BIM)的技術至今已推廣多年，各先進國家都將其列為目前優先發展之工程技術，持續推動並落實BIM技術之基礎。從生命週期來看，BIM技術確實已逐漸推廣於工程規劃及設計階段，顧問公司或建築師採用BIM相關設計軟體進行規劃設計之案例也不斷增加。此發展可歸功於BIM具有優異的可視化圖形，並具有大量的尺寸、數量、材質、碰撞檢測等資訊與功能，對於設計單位能夠有效提升其內部檢討及溝通之效率。然而脫離設計建模(modeling)階段，因資訊整合不易，復以過去資訊管理系統開發不擅長如何將BIM之3D空間視覺介面帶入各階段之應用中，是故BIM技術在營建施工乃至建物使用維護階段仍無法廣泛應用，有待產官學三方持續努力。
在上述背景下，行政院刻正推動之「數位國家‧創新經濟發展方案(106~114年) 」、「前瞻基礎建設計畫」之「數位建設‐營造智慧國土」與內政部「建構永續宜居環境」等重要相關政策。為此，本計畫以落實風工程技術及建築資訊模型(BIM)之創新多元整合應用與跨領域人才之培養為目標，結合CFD模擬、風洞實驗、物聯網(IoT)、建築資訊模型等技術，以建築內自然通風效率最佳化為導向，實現智慧化建築通風即時監控系統與機制，創造節能之居住環境，提升人民綠生活之居住品質，以達成「節能再生的低碳家園」、「潔淨健康的生活環境」與「國土建設永續發展」的整體政策目標。
綜言之，為了提供即時的室內自然通風決策資訊給住戶，必需有效整合即時外部風場及內部風場資訊。如何根據外部風場的狀態，即時求得最佳的建築開窗模式已產生最合適的室內通風效果一直是個難題。在建築物設計分析階段，可透過CFD分析模擬各種室外風場下，不同建物開窗方式所產生的室內通風結果。然此方法需大量的計算，無法提供建築物使用維護階段之即時決策使用。為此，本研究希望藉由建築物資訊模型之應用，一方面利用建築物資訊模型進行室內外風場實驗與模擬，求得室內自然通風的最佳化資訊；一方面以建築資訊模型作為資訊整合載體，將最佳化資訊結果整合於建築資訊模型資料庫中，進而透過資訊系統之開發，建立一個可以即時量測室外風場及室內環境參數，並據以查詢最佳通風策略之室內自然通風決策系統。
二、研究方法及過程
為建立最佳化通風分析，研究擬選定一有自然通風需求之目標建築進行分析。本建築位於台灣南部，為樓高8層且附近為空曠區域，室內空間寬敞無複雜隔間，適合於夏季進行自然通風。為求得此案例的自然通風最佳化開窗模式，本研究將先後以風洞實驗及CFD數值模擬方式建立「建物自然通風數值模型」。也就是於風洞實驗中獲取建物開窗部位之建築表面風壓，再將對應之風壓係數導入CFD室內通風模型中進行不同開窗配置之通風分析，藉以求得該建物在不同外部風場環境下所對應不同開窗配置之室內自然通風資訊。
為了使「建物自然通風數值模型」能落實在建物營運維護階段，本次透過建物BIM空間模型與通風數值模型的資料串連，開發「BIM建築物室內通風管理系統」。考量系統開發及使用成本之因素，本研究採用Unity3D作為BIM模型之加值應用開發工具，並利用自行發展之「視覺化多維度資訊整合架構」進行系統整合機制。
上述所使用之相關方法概述如下（詳細內容請詳報告章節）：
1.風洞試驗
於風洞中設置目標建築之縮尺模型，量測在不同水平風向角下模型各開窗位置之風壓數據，其結果係作為建築壓力模擬驗證比對之依據，以及室內模擬區域開窗部之壓力邊界條件。
風洞試驗內容包括：
(1)來流風況：C地況，0 ~ 337.5，每22.5轉風向角一次，共16個水平風向角。
(2)目標建築模型1座，包含半徑100公尺範圍內建築。
(3)針對目標建築物模型開口區域進行風壓量測，獲得表面風壓(時均值與均方根值)之空間分佈結果。
2.CFD模擬
針對目標建築其中1個代表樓層之室內空間進行模擬，
(1)來流風況：根據風洞實驗量測之風壓結果，將16個水平風向角之風壓數據輸入分析。
(2)針對目標樓層模擬數個可控制開關之窗戶情形，改變不同開窗條件(扣除完全不開以及僅開1扇窗的無法產生貫流通風狀況)求得各種條件下的室內空氣流場數值。
3.Unity 3D
Unity3D遊戲引擎為現今廣被使用的遊戲引擎之一，主要可支持多平台系統之開發，例如Windows、macOS、Linux作業系統之線上與單機遊戲以及Android、iOS行動裝置應用程式(Application, APP)等。在開發上主要以物件導向的程式設計邏輯為基礎，並搭配C#、JavaScript程式語言，讓使用者以較為不受限的方式依照個人的需求進行程式的互動設計與開發。在開發的過程中，Unity 3D遊戲引擎提供使用者一個3D可視化的場景進行開發，並結合2D使用者介面(User Interface, UI)的開發環境，讓使用者方便進行3D介面為基礎之遊戲開發，其中Unity也提供了多種3D模型格式的支持，其中包括 *.3ds、*.dxf、*.dae、*.obj、*.fbx 等，使得在本研究得已整合不同之BIM模型檔案，讓系統的製作上更為多元。除此之外Unity3D遊戲引擎還具有大量的第三方插件支援，協助使用者功能需求上的開發更為便捷。有鑒於此，本研究將利用Unity3D遊戲引擎高度的跨平台性、互動性、客制化、開發自由度及3D畫面呈現的能力為基礎，作為系統主要之開發環境，藉此開發出一個有利於BIM 3D模型加值應用及營建資訊整合的視覺化建物自然通風管理系統。
4.視覺化多維度資訊整合架構
為有效拓展BIM於營建產業全生命週期之應用，根據既有BIM 3D模型與營建資訊管理系統整合之需求，本研究將利用自行設計之「視覺化多維度資訊整合架構(Visualized Multi-dimensional Information Integration Framework, VMDIIF)」，以Unity3D遊戲引擎及網頁為主要開發環境，並結合虛擬實境(Virtual Reality, VR)之技術，提供一個以BIM 3D模型為基礎之圖形化操作介面，其中包含了三個主要之項目：「混合式資料庫(Hybrid Database) 」、「系統維護管理模組」及「視覺化多維度資訊應用程式」，作為往後整合開發之參考。
三、重要發現
(1)室內自然通風決策模式
在以室外風場及預先分析所得之室內CFD風場資訊為判斷依據為前題下，本研究以「體感溫度」及「PMV熱感舒適度指標」等二種舒適度指標作為最適室內通風之決策因子，分別擬定以「目標體感溫度」及「最大舒適空間率」之決策模式作為「建築物室內通風決策系統」開發之用。然此系統並不限於此二種決策模式。只要可依據室外風場及室內CFD場資訊為基礎之決策方式皆可用以修正或新增至系統中，提供更完善之室內自然通風決策建議。
(2)實場資訊量測系統
本研究透過「實時外部風場資訊量測裝置」、「實時室內通風環境量測裝置」、「外部風場實時網頁」與「建物實場環境資料庫」之建立，已經達成以「實場資訊量測系統」自動收集室內外通風環境資訊，並將資訊整理上傳至資料庫，為後續最佳化通風決策提供依據之目標。此外，「實場資訊量測系統」因採開放式架構進行開發，故後續仍可依照可能之室內通風環境決策之需求，在現有的實時量測裝置的基礎上擴充傳感器數量與類型以保證此系統未來之延續性。
(3)建物自然通風模型數值資料庫
以風洞實驗得到建物表面風壓作為CFD室內自然通風模擬之邊界條件，並利用CFD模擬分析求得建築物室內風場分布資料、平均風速及換氣率等數據。透過整合上述CFD模擬數據與建築物BIM模型資料，完成「建物自然通風模型數值資料庫」之設計、建置及資料儲存，以作為「BIM建築物室內通風決策系統」的核心資料庫。
(4)BIM建築物室內通風決策系統
完成「BIM建築物室內通風決策系統」之開發。透過遊戲引擎平台之開發環境，成功整合上述「實場資訊量測系統」、「建物自然通風模型數值資料庫」及建築物BIM 3D模型，建置一個以建築模型為操作介面，可自由切換各樓層模型，並呈現各樓層室內外風場及環境即時資訊，更可依據室外風場狀況分別以體感溫度及PMV熱感指標提供最佳通風決策之系統。透過此系統之實作，也實現了將CFD等預先分析數據(pre-analysis data)進行儲存，進而帶入後續建物使用維護階段進行應用之方法論。
四、主要建議事項
建議一
本案研究成果提供相關學會團體建置資訊平台於實體公共建築展示空間：立即可行建議
主辦單位：社團法人中華民國風工程學會
協辦單位：財團法人台灣建築中心
建議選擇具備基礎智慧建築設施設備之案場，利用本研究所建置之軟硬體系統針對該案場現有之可行設備進行整合，並發展合適展演教材與教具，透過展演方式使民眾經由系統操作，了解外部風場與室內自然通風關聯，進而推廣節能、智慧建築、物聯網應用等知識與概念，展現本所研究成果。
建議二
建議辦理風工程相關實場監測即時量測技術研究：中長期建議
主辦單位：社團法人中華民國風工程學會
基於本案研究成果建立之物聯網技術，可進一步擴增應用於風工程相關之實場監測技術。例如建立戶外風環境即時資訊系統，可應用於社區、校園或大型戶外公共空間，提供即時區域微氣候資訊，實時判斷戶外微氣候之良窳，提供民眾戶外休憩活動之可靠指標，創造智能之宜居環境，進一步提升人民綠生活之居住品質。同時，戶外風場資料在經過長時間蒐集後，可與氣象站資料整合進行整合分析，透過大數據或人工智慧技術處理，可補強設計風速資料來源。本技術亦可應用於建築結構監測，搭配GPS、加速度計、壓力量測等設備，即時監控並蒐集建築之風壓、振動等資訊，作為建築抗風之風洞實驗驗證或理論模式發展依據。

I.Background
In the face of the threat of global warming, carbon reduction has become the world's collective initiatives. Under this trend, Taiwan is also actively striving to build a sustainable and livable environment and enhance the application of smart green technology. It is hoped that while reducing the energy consumption of buildings, it can also take into account the basic needs of livable space. Indoor ventilation affects not only the temperature of the space but also the health of the building user. How to effectively introduce external wind farms, use natural ventilation mechanism to reduce the consumption of building air conditioning energy, or provide a healthy living environment is an essential issue in current maintenance. The airflow environment and air quality in the building often depend on the ventilation effect in the indoor space. Taiwan is located in a subtropical climate zone; accordingly, it has been able to exchange indoor and outdoor air through natural ventilation to achieve the purpose of regulating indoor air temperature and quality almost for six months in one year.
With the development of new technologies and new construction methods, the quality and diversity of engineering technologies have expanded dramatically, and the building information has become more complicated. The construction industry and researchers continue to use information technology to provide more accurate and practical building information for all phases of the b life cycle, and to move toward the goal of building life cycle information integration and smart management. The technology of Building Information Modeling (BIM) has been promoted for many years, and all advanced countries have served it as the priority engineering technology. From the perspective of the life cycle, BIM technology has gradually been well applied in the engineering planning and design stage. However, because the cross-stage information integration is severe, the BIM technology cannot be widely applied in the construction and maintenance phases of the building.
To provide immediate indoor natural ventilation decision information to residents, it is necessary to effectively integrate the external wind field and internal wind field information. How to get the best indoor ventilation mode based on the state of the external wind farm has been the most suitable indoor ventilation effect. In the stage of building design analysis, CFD analysis can be used to simulate the indoor ventilation results by different building windows conditions in various outdoor wind fields. However, this method requires massive calculations and cannot provide immediate decision-making for the maintenance phase of the building. To this end, this study hopes to use the building information model to conduct indoor and outdoor wind field experiments and simulations on the one hand, and to obtain the optimal information of indoor natural ventilation. On the other hand, the building information model is used as the information container for integrating the optimized information results. Then through the development of the information system, an indoor natural ventilation decision-making system that can measure the outdoor wind field, indoor environmental parameters, and query the optimal ventilation strategy can be established.
II.Research methods and processes
In order to establish an optimized ventilation analysis, the study plans to select a target building with natural ventilation requirements for analysis. Located in the southern part of Taiwan, the building is an 8-story building with open space nearby. The interior is spacious and has no complicated compartments. It is suitable for natural ventilation in the summer. In order to obtain the natural ventilation and window opening mode of this case, this study will establish the “Numerical Model of Natural Ventilation of Building” by wind tunnel experiment and CFD numerical simulation. That is, obtaining the wind pressure of the building surface by the wind tunnel experiment, and then introduce the corresponding wind pressure coefficient into the CFD indoor ventilation model to conduct ventilation analysis of different window opening configurations. Accordingly, the indoor natural ventilation information corresponding to different window openings in different external wind field can be provided.
In order to implement the "Numerical Ventilation Numerical Model" in the building operation and maintenance phase, the "BIM Building Indoor Ventilation Management System" was developed through the connecting BIM space information with the numerical ventilation model. Considering the factors of system development and usage cost, we used Unity3D as a value-added application development tool for the BIM model and applied the self-developed "visualized multi-dimensional information integration architecture" to implement the system integration mechanism.
III.Conclusions
1.Indoor natural ventilation decision modes: under the premise of the outdoor wind field and the pre-analyzed indoor CFD wind field information, this study applied "apparent temperature" and "PMV" as the optimal factors for the indoor ventilation decision making. These two decision-making factors are respectively used to develop the "somatosensory target temperature decision mode " and "maximum comfort-space rate decision mode " in the building indoor ventilation decision system. However, this system is not limited to these two decision modes. As long as the decision-making methods based on the outdoor wind farm and indoor CFD field information can be used to modify or add to the system, provide better indoor natural ventilation decision-making advice.
2.Real-time environment measuring system: through the establishment of "Real-time external wind field measuring device," "Real-time indoor ventilation environment measuring device," "External wind field real-time webpage," and "Building environmental database," the study has achieved real-time environment measuring system. The system automatically collects and stores information on the indoor and outdoor ventilation environment. Also, the real-time environment measuring system has been developed based on an open architecture. Therefore, the various sensors can be integrated into the system following the potential requirements of the different indoor ventilation decision-making necessary in the future.
3.Natural ventilation model database: the surface pressure of the building by wind tunnel experiment is taken as the boundary condition of the CFD analysis for natural ventilation simulation. The wind field distribution, average wind speed, and air exchange rate of the indoor space of the target building are obtained by CFD simulation analysis. Through the integration of the above CFD simulation data and BIM model data, the design, implementation, and data storage of the natural ventilation model database was completed as the core of the Building Indoor Ventilation Decision System.
4.BIM building indoor ventilation decision system: through the successful integration of the above-mentioned "real-time environment measuring system", "natural ventilation model database," and building BIM 3D model by the game engine platform, the development of "BIM Building Indoor Ventilation Management System" was completed. The system uses the BIM model as the operation interface, and can freely switch to each floor in the BIM model, and present the indoor and outdoor wind field and environment real-time information of each floor, and can provide optimal ventilation decision according to the indoor temperature field and the PMV thermal index. In addition, through the implementation of this system, the method of storing pre-analysis data such as CFD and carrying it into the subsequent construction and maintenance phase is also realized.
IV.Recommendations
For immediate strategies:
1.Applying the system to the public exhibition space: chose the proper exhibition place with necessary intelligent building facilities, equipment, softwares, and hardware system; use the developed system in this study to integrate the existing feasible equipment of the case. In turn, the development of suitable exhibition materials will enable the public to understand the relationship between external wind farms and indoor natural ventilation through the operation of the system and achieve the goal of promoting energy-saving, intelligent buildings, and Internet of Things applications.
For mid-term strategies:
2.The research of outdoor pedestrian wind environment real-time information system: based on the Internet of Things technology established in this study, the advanced application of outdoor building microclimate can be developed. The establishment of an outdoor pedestrian wind environment real-time information system can be applied to communities, campuses, or large outdoor public spaces, providing instant regional microclimate information, real-time judgment of outdoor microclimates, and providing reliable indicators of outdoor recreation activities. Realizing this real-time information system,  we can make it possible to create a smart and livable environment to further enhance the living quality of the people's green life.
3.Integration and development of indoor air quality intelligent management system: Based on the research results and experience and the relevant regulations of indoor air quality management, we can apply suitable indoor air quality measuring sensors and indoor mechanical ventilation/air conditioning solutions in the market to implement an indoor ventilation control system considering both of the natural and mechanical ventilation. Further, through this system, real-time data collection and analysis of indoor air quality and wind field can be carried out, and artificial intelligence algorithms such as deep learning can be combined to establish a ventilation decision mode suitable for different indoor spaces.