建築工程材料碳排放分析研究－以RC建築為例

Abstract

近年來，隨著永續與環保理念日益普及，全球各國紛紛制定相關法規以邁向淨零碳排目標，根據統計，營建產業約佔全球總碳排放量之42%，其中以營運碳(Operational Carbon)與蘊含碳(Embodied Carbon)之比例約為三比一。基於此背景，本研究聚焦於鋼筋混凝土(RC)建築物之蘊含碳進行探討。 本文採用ISO 14067作為碳盤查之評估方法，先蒐集建築工程中所使用之材料與數量，乘以對應之碳排放係數，以計算各材料所產生之碳排量，並加總得出建築物之總蘊含碳排放量，並以「工程數量法」稱之。此方法在生命週期評估（Life Cycle Assessment, LCA）之範疇中，本文僅涵蓋原物料製造、生產與運輸過程之碳排放，未納入使用與廢棄階段之考量。 本研究將碳排比較分成三階段，第一階段為整體建物之碳排密度比較(21項案例)，使用工程預算書中所有工項與內政部建築研究所公布之《低碳建築評估手冊(LEBR)》進行比較。第二階段則針對地上層主結構體討論(27項案例)，使用工程估算書或直接使用結構計算書計算柱梁板結構體之鋼筋及混凝土用量，探討低碳建築評估手冊之迴歸式預測準確性。第三階段使用工程估算書(8項案例)，計算主結構體柱梁板牆及樓梯之鋼筋及混凝土用量，探討其用量與整棟建物之關係。 在整體建物之碳排密度比較結果中，工程預算書之碳排密度約664.16 ± 87.89 kgCO₂e/m²，LEBR之碳排密度約412.35 ± 34.80 kgCO₂e/m²。若僅考量鋼筋及混凝土用量結果，工程估算書之碳排密度約547.26 ± 41.53 kgCO₂e/m²，占總工程之碳排密度約61% ~ 72%。 整體而言，主結構體約占營造階段總碳排放量的70% 至 90%，其中以混凝土與鋼筋用量為主要影響因素。由此可見，採用「工程數量法」進行碳排估算，不僅有助於提升估算準確性，亦可快速掌握減碳熱點，反映設計變異性，可作為設計初期碳排量評估之可行方法，具有實務應用與推廣之潛力。

In recent years, with the growing emphasis on sustainability and environmental protection, governments around the world have implemented regulations aimed at achieving net-zero carbon emissions. The construction industry accounts for approximately 42% of global carbon emissions, with a ratio of operational carbon to embodied carbon of roughly 3:1. Against this backdrop, this study focuses on the assessment of embodied carbon in reinforced concrete (RC) buildings. This research adopts ISO 14067 as the carbon footprint assessment framework. A method referred to as the "Quantity-based Method" is used, which involves collecting data on the types and quantities of construction materials used in a project, multiplying them by their respective carbon emission factors, and summing the results to estimate the total embodied carbon emissions of the building. Within the scope of Life Cycle Assessment (LCA), this study considers only the emissions generated during the production, manufacturing, and transportation stages of raw materials, excluding emissions from the use and end-of-life phases. The analysis is divided into three stages. In the first stage, the carbon emission density of entire buildings is compared across 21 cases, using the full list of work items from construction budgets and referencing the Manual of Low Embodied-carbon Building Rating System (LEBR) published by the Architecture and Building Research Institute (ABRI). The second stage focuses on the above-ground primary structural components in 27 cases. Using quantity estimates or structural analysis documents, the study calculates the amounts of rebar and concrete used in beams, columns, and slabs to evaluate the predictive accuracy of the LEBR regression model. In the third stage, based on 8 selected cases, the quantities of rebar and concrete used in columns, beams, slabs, walls, and stairs are analyzed to explore their relationship with the building’s overall embodied carbon. The results indicate that the carbon emission density calculated from construction budgets is approximately 664.16 ± 87.89 kgCO₂e/m², while the LEBR model yields about 412.35 ± 34.80 kgCO₂e/m². When only rebar and concrete are considered, the carbon emission density derived from quantity estimates is approximately 547.26 ± 41.53 kgCO₂e/m², accounting for roughly 61% to 72% of total construction-phase emissions. Overall, the primary structural system contributes approximately 70% to 90% of total embodied carbon emissions during construction, with rebar and concrete being the dominant influencing factors. These findings suggest that the Quantity-based Method not only improves estimation accuracy but also facilitates rapid identification of carbon-intensive elements, reflects design variability, and serves as a practical and feasible approach for embodied carbon assessment during early design stages.