This paper deals with the methodologies and databases for comparative assessment of emissions of greenhouse gases (GHGs) from the full energy chain (FENCH) of different energy sources, It largely refers to an international experts workshop on the topic held in October 1994 in Beijing, which was the first meeting in a series of IAEA expert meetings on comparison of FENCH-GHG emission from energy sources, The findings and recommendations of the workship cover topics such as time horizon, plant life time, materials flows and system output comparability.