Calculation and structural analysis of total factor energy efficiency in high carbon sectors.

High carbon sectors (agriculture, industry, construction, and transportation) contribute nearly 85% of carbon emissions, highlighting the urgent need for transitioning towards cleaner energy structures in these sectors. This study utilizes the undesirable SBM model to assess TFEE (total factor energy efficiency) across the total sector and high carbon sectors. It decomposes TFEE from an energy structural perspective into coal, oil, natural gas, and electric heat efficiencies. Using a variance-like decomposition model, it analyzes TFEE at two levels to examine how changes in specific sectors and energy categories affect total sector TFEE. From 2010 to 2021, China's total sector TFEE increased from 0.542 to 0.676, with electric heat and coal identified as critical factors limiting TFEE improvements. Among the four high carbon sectors, construction exhibited a significant increase in TFEE, agriculture showed a steep rise, the industry demonstrated a U-shaped trend with a turning point in 2015, and transportation experienced a slight decline. TFEE exhibits a descending order among sectors, with agriculture ranking highest, followed by construction, industry, and transportation. Similarly, the total factor efficiencies of energy types show a hierarchical structure, with oil being the most efficient, followed by electric heat, natural gas, and coal. Construction dominates TFEE changes at the sectoral level, contributing 58.87%, while coal contributes over 30% at the energy category level. The decomposition results for each province further indicate that both sectoral structure and energy structure significantly impact the changes in TFEE, and this influence also exhibits regional heterogeneity.