We investigate the progress of the UK universities in greening their energy sources in line with the UK's goal of becoming a net-zero economy by 2050. Using the HESA estate management data for 116 universities over 2012-13 to 2018â€“19, we employ a Log Mean Divisa Index decomposition method within an extended Kaya identity framework to decouple the changes in total carbon emissions from a range of variables, with a special focus on the impact of different energy sources on energy use and carbon efficiency measures. Overall, between 2012-13 and 2018â€“19, universities have reduced emissions by 29% although their energy consumption remained mostly stable, implying that these reductions mostly stemmed from reductions in emission coefficient effect (which measures carbon efficiency of energy generation) by 24% and energy intensity effect by 25%. Consistently, estimated correlation coefficients confirm that emission coefficient, intensity, and affluence effects are major contributors behind the annual change in total emissions, with estimated correlation coefficients being 0.42, 0.66, and âˆ’0.24, respectively. The share of renewable energy sources was reduced by 2.2%, which is a major reason, in addition to increased number of students, behind the sector's overall failure achieve the 2020 goal of reducing emissions by 43% from the 2005 level. Finally, our results also expose considerable regional variations in mitigating and worsening factors behind emissions that calls for stronger coordination and supervision by policymakers.