辦公建築空調系統之生命週期經濟效益分析研究—以地方政府廳舍冰水主機房汰舊換新為例

Research on the Economic Analysis of HVAC System Life Cycle for Public Office Building –Case Studies on a City Hall Chiller Plant Retrofit

詹邦鎮(Pan-Chen Chan)

指導教授 ： 楊詩弘

國立臺北科技大學/設計學院/建築與都市設計研究所/碩士(2008年)

摘要

辦公建築設備面臨汰舊換新時，建築的使用狀況可能與原始規劃的用途迥異，藉由電腦輔助能源模擬軟體，依據建築現況的物理特性與建築的使用模式，可以早期預估能源的使用。如果建築物運轉階段導入能源管理系統，校正建築物電腦輔助耗能的模擬，重建趨近現實的耗能模型。當建築物需要性能再提升的階段，運用這個可靠的耗能的模型，輔以生命週期成本概念，分析建築所需進行與能源有關之主動式與被動式節能改善計畫的節能效益預測，提供經濟效益分析報告給決策者，做為建築生命週期最佳化管理有用的輔助決策工具。
本論文經由實際案例之研究，採用本文採用的生命週期最佳化管理工具進行汰舊換新，得到的結論如下：
一、電腦輔助耗能模擬的適用性驗證
本研究採用電費單與抄錶記錄校正校正建築物電腦輔助耗能的模擬，建立了案例建築的耗能模型，其MBE(Mean Bias Error)誤差值在-9.5%~3.4%之間。用這個耗能模型再經由動態模擬預測設計方案的耗能，分析預測的耗能量與能源管理系統量測記錄的耗電量，除了97年2月因為春節放假日較多以外，其餘月份的MBE誤差值都在-5.94%到+11.35%之間，驗證使用這個方式預測未來的耗電量是具有可靠度。
二、工程投資經濟效益分析
本研究分析五個不同設計方案，預估僅進行空調設備汰換的選項三之節能效益為18%，而採用變頻冰水主機搭配定頻離心式冰水主機、變頻控制冷卻水塔與變頻控制二次冰水泵的設計選項二預估可達到40.8%。另外，以生命週期成本的概念進行經濟效益評估，設計選項二的生命週期成本最低，經濟效益最大。其次為採用定頻離心式冰水主機、變頻控制冷卻水塔與變頻控制二次冰水泵的設計選項一。這兩個經濟效益較佳的系統互相比較，得到節省與投資比率 (Savings to Investment Ratio, SIR)為5.836，採用選項二的還本期為3.8年，雖然值得投資，但是案例為公部門公開招標的工程案件，囿於初設成本高於預算太多而成遺珠。本研究發現選項二是最具經濟效益的選項，因此，政府公部門在建築進行節能工程的計劃階段，採用本研究的決策程序將可以得到最佳的設計方案。
三、生命週期最佳化管理工具
本研究經由一系列的操作，藉由抄錶數據與電費單修正電腦動態耗能模擬，得到了可信度高的耗能模型，預測不同設計提案的耗能狀況，並以生命週期理論分析個別的工程投資經濟效益，找到合乎預算的最佳設計方案。並且導入了能源管理系統以實測的數據比較上述程序所預測的耗能，驗證這個決策程序是可行的。

因此，既有辦公建築建立與保存耗能模型，並導入建築物能源管理系統，未來建築物進行節能性能再提升時，在計畫的階段便可以得到準確的生命週期成本與經濟效益分析，提供建築設施管理者決策參考，找到較低生命週期成本且最具經濟效益的設計方案，確實有利於建築物生命週期管理。

關鍵字

建築動態耗能模擬 ； 生命週期成本 ； 經濟效益分析 ； 能源管理系統 ； 驗證 ； 汰舊換新

並列摘要

The space purpose of the building might be different from original when facility meets retrofit needs. It is necessary to anticipate energy consumption for making a retrofit decision. So that, to use a computer base building energy simulation system to anticipate post-retrofit energy consumption. In the operation stage, we can easily represent the building energy scenario by calibrated simulation with the simultaneous electrical data record from the Building Energy Management System. Thus, the individual alternative’s post-retrofit energy scenario can be simulated to assess the life-cycle cost during retrofit planning stage.

The research study pre-retrofit and post-retrofit stage from the public building chiller plant retrofit project and shows the conclusions as below:

1. Re-Model Existing Building With Computer Base Building Energy Simulation
The research performs whole building calibrated simulation to represent the building energy behavior. The mean bias error (MBE) is range from -9.5% to 3.4% by comparison from utility bill and simulated data. It is acceptable from ASHRAE Guideline 14-2002, for using the building energy characteristic to simulate the post-retrofit scenario to estimate the future energy consumption. Furthermore, the MBE is range from –5.94% to 11.35% after the comparison of anticipation and the reality data from EMS. That shows the decision making process is feasible for life-cycle management.

2. Engineering Economic Analysis With Life-Cycle Cost Concept
The research studies five alternatives based on the biding scope from the building owner. Option 1 is to re-model chiller plant. Option 2 is also re-model chiller plant with variable speed centrifugal chiller. The option 3 is simply replace old equipment without system re-model. Option 4 is simply replace old equipment with variable speed cooling tower and secondary chilled water pump. Option 5 is simply replace old equipment with secondary chilled water pump. The research input the system characteristics into the building model simulation software for post-retrofit energy consumption and further economic analysis. From the post-retrofit energy consumption that shows the most efficient system is option 2 which is saving 40.8%. The worse one is simply equipment replace case - option 3, whose efficiency is 18%. The research also shows option 2 is the lowest life-cycle cost and the valuable design. However, option 1 has been chosen because of the initial cost of the option 2 is higher than budget. After comparing from option 1 and option 3, the SIR is 5.836 and payback period is shorter than 3.8 years during 15 years life-cycle.

3. Optimize the Life-Cycle Management
During the series assessment, shows the process can account the life-cycle cost to look for the optimum design option with representing building model. And, the model has been simulated from simultaneous energy behavior by collecting utility bill and electrical data record. In post-retrofit stage, the chiller plant running over 6 months and collects data from EMS for the post-retrofit system commissioning. The result shows the optimum energy-saving system is now running and under a predicted efficiency.

Thus, the research proof the procedure is feasible to life-cycle management for existing office buildings in Taiwan.

並列關鍵字

Simulation ； Life-Cycle Cost ； Engineering Economic Analysis ； Energy Management System ； Commissioning ； Retrofit

參考文獻

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