台灣地區木構造住宅對碳貯存與二氧化碳減量之貢獻

Abstract

木構造建築物以木材當作主要建材，不但在建設階段會比其他構造建築物省能源，進而使CO2排放減量；同時在其生命週期內，均可將碳素固定在建築物內部，不會使其回歸大氣中。IPCC亦已針對伐採木材的使用對碳素貯藏機能的評價方法進行討論，本論文即以木構造建築物作為研究對象，分析探討木構造建築物的市場現況與木構造建築物對碳貯存與二氧化碳減量之貢獻。 研究結果顯示，在各種不同工法木構造房屋建築中，框組壁工法與樑柱式工法二者合計約佔全部木構造房屋建築數量的70%，是目前主要的木構造房屋建築型式；而雲杉-松-冷杉類 (SPF)與花旗松(Douglas fir) 是木構造房屋建築最重要的二種材料，各約佔木構建築用材消耗比例的35.49%及27.24%。木屋業者認為經營成本、建築業房屋市場、國內法令規定與國內環保問題等是在未來經營上所主要關心的問題。 在不同建築工法型式的木構造建築物中，樑柱工法木構造建築平均每單位建築面積所使用之木質材料材積約為0.2090 m3/m2，框組壁工法木構造建築約為0.2143 m3/m2，而D-log工法木構造建築則約為0.2455 m3/m2，以D-log工法木構造建築平均每單位建築面積所使用之木質材料材積最多，若不計建築工法型式時，平均每單位建築面積之木質材料使用量則約為0.2133 m3/m2。 平均每單位建築面積木構造建築物的CO2排放量是以D-log工法木構造建築最大，每單位建築面積CO2排放量約為61.46 kg/m2；樑柱工法木構造建築平均每單位建築面積CO2排放量約為47.47 kg/m2，而框組壁工法木構造建築每單位建築面積CO2排放量約為57.42 kg/m2。若不計建築工法型式時，全體木構造建築平均每單位建築面積CO2排放量約為54.41 kg/m2。 每單位建築面積鋼筋混凝土構造建築物與鋼構造建築物的CO2排放量各為木構造建築的4.54倍及3.64倍，若以木質構造建築取代鋼筋混凝土與鋼構造建築物時，可削減的CO2排放量分別約為388.21 kg/m2與339.05 kg/m2，顯示木構造建築在CO2減量與碳素固定上具有顯著的效果。以蓄積量變化法推估至2012年時，台灣地區既存的木構造建築累積的碳素貯存量將約為6.5萬公噸；而在第二約束期間(2013 - 2017年)，新建木構造建築每年增加的碳素貯存量將約為3,800公噸。

Wooden construction buildings use wooden products as the main construction materials; therefore, they consumed less energy and reduce carbon dioxide emissions than other kinds of buildings did during construction process. Meanwhile, wooden construction buildings could sequestrate carbon within buildings during their life time. The evaluation methods of carbon sequestration in harvested wood products have been taken into discussion by IPCC. The dissertation is focus on wooden construction buildings to analyze their current market situation and to evaluate their contribution of carbon sequestration and carbon dioxide reduction. Results indicated that the platform (2 X 4) and post and beam (PNB) wooden construction buildings were the major types of wooden houses which shared approximately 70% of total wooden houses in Taiwan. Both spruce-pine-fir and Douglas fir were used as construction materials mostly. The following problems were perceived by wooden house construction companies, mostly related to their future concerns: lumber prices, labor costs, fluctuation of business cycles, competition from non-wooden houses, domestic construction laws and regulations, and disposal of wooden waste. The usage of wood materials in per unit construction area of wooden construction houses was 0.2133 m3/m2 ; and the carbon dioxide emission in per unit construction area was 54.41 kg/m2. Comparing the wooden construction with reinforced concrete (RC) and steel prefabricated (S) constructions, the carbon dioxide emission reduction of the wooden construction are 388.21kg/m2 and 339.05 kg/m2 of two previous major methods, respectively. The results showed that wooden construction buildings have significant ability in carbon sequestration and carbon dioxide reduction. The quantity of carbon sequestration is estimated to be 65 thousand tons until 2012, and it is expected to increase 3,800 tons per year during 2013-2017 by the stock change approach.