Ecological total-factor energy efficiency of regions in China

► Most energy efficiency indices ignore undesirable outputs such as CO2 and SO2 emissions. ► The ecological total-factor energy efficiency (ETFEE) is computed by slack-based model (SBM). ► The datasets contains 30 regions in China for the period 2005-2009. ► China's regional energy efficiency is extremely unbalanced. ► A monotone increasing relation exists between ETFEE and per capita GDP.