本研究旨在探討越南製造業中，外資所有權廠商之能源使用效率是否優於本土企業，並檢驗外資是否存在技術外溢效果以提升本土企業的能源效率。本文採用越南中央統計總局（General Statistical Office， GSO）2009與2011至2015年的企業調查（Annual Enterprises Survey， AES）資料。實證方法分為兩階段：第一階段採用乘法分解之LMDI-I (Logarithmic Mean Divisia Index)能源強度分解模型（Multiplicative LMDI-I model for energy intensity decomposition），分離出單一廠商內部之能源強度效應，以此作為衡量其動態能源效率改善速率之指標；第二階段則建構面板資料固定效應模型，進一步評估所有權結構與外資外溢效果對廠商能源效率的動態影響。 實證結果顯示，第一，外資廠商相較於本土私營企業，在動態效率改善率上並無顯著持續優勢，暗示外資技術已接近前沿，邊際提升空間有限；反之，國營企業改善速率顯著較慢，節能表現最具劣勢。第二，外資技術外溢因能源類別展現顯著的時間異質性，在高耗能之本土私營企業樣本下，外資對燃料效率具顯著當期正向外溢；對電力效率的外溢則需滯後至落後兩期方顯著。此結果證實外資存在轉型推力，但也反映本土企業因應不同能源類型時，其技術吸收與設備汰換的磨合週期存在本質差異。;This study investigates whether foreign-invested enterprises (FIEs) in the Vietnamese manufacturing sector exhibit superior energy efficiency compared to domestic firms， and examines the potential technical spillover effects of foreign capital on upgrading domestic firms′ energy efficiency. Utilizing micro-level data from the Annual Enterprises Survey (AES) conducted by the General Statistical Office (GSO) of Vietnam for 2009 and from 2011 to 2015， the empirical analysis is carried out in two stages. The first stage employs the multiplicative LMDI-I model for energy intensity decomposition to isolate the firm-level energy intensity effect， which serves as the indicator for dynamic energy efficiency improvement rates. The second stage constructs a panel data fixed effects (FE) model to further evaluate the dynamic impacts of ownership structures and foreign spillovers on firm energy efficiency. The empirical results demonstrate the following: First， regarding the dynamic efficiency improvement rate， foreign firms do not exhibit a statistically significant or sustained advantage over domestic private firms. This implies that foreign firms had already approached the technology frontier upon entering the Vietnamese market， leaving limited marginal room for subsequent efficiency gains. Conversely， state-owned enterprises (SOEs) show a significantly slower rate of efficiency improvement， representing the greatest disadvantage in energy-saving performance. Second， foreign technical spillovers display prominent temporal heterogeneity across different energy categories. Within the subsample of domestic private firms in energy-intensive industries (EIIS)， foreign presence exerts a significant contemporaneous positive spillover on fuel efficiency. However， the spillover effect on electricity efficiency is lagged， becoming statistically significant only at the second lag (L2). These findings confirm that foreign investment provides a driving force for the green transition of Vietnamese manufacturing， while also reflecting that domestic firms face inherent differences in their technology absorptive capacity and equipment-retrofitting cycles when adjusting to different energy types.
