The energy system plays an essential role in accounting of greenhouse gas (GHG) emissions from waste management systems and waste technologies. This paper focuses on energy use and energy recovery in waste management and outlines how these aspects should be addressed consistently in a GHG perspective. Essential GHG emission data for the most common fuels, electricity and heat are provided. Average data on electricity provision show large variations from country to country due to different fuels being used and different efficiencies for electricity production in the individual countries (0.007—1.13 kg CO2-eq. kWh—1). Marginal data on electricity provision show even larger variations (0.004—3 kg CO2-eq. kWh —1). Somewhat less variation in GHG emissions is being found for heat production (0.01—0.69 kg CO2-eq. kWh —1). The paper further addresses allocation principles and the importance of applying either average or marginal energy data, and it discusses the consequences of introducing reduction targets on CO 2 emissions. All discussed aspects were found to significantly affect the outcome of GHG accounts suggesting transparent reporting to be critical. Recommendations for use of average/marginal energy data are provided.