Dynamic CO2 emission factors for the German electricity mix. In recent years, the German Energiewende has led to a significant increase in the renewable energy share of the electricity generation. While being characterized by lower specific CO2 and greenhouse gas emissions over the life cycle in comparison to conventional power generation, the expansion of electricity production from wind and solar energy makes a vital contribution to climate protection. In the context of emission balances, adjustments of the specific emission factors continue to account for the ongoing improvement of the electricity mix. However, an expedient evaluation of innovative and electrified energy supply concepts is virtually impossible using static emission factors based on the annual energy demand. Therefore, this paper describes a methodology to calculate CO2 and greenhouse gas emissions for the German electricity mix 2017 dynamically with a temporal resolution of 15 minutes. For this purpose, open source time series for the electricity production are processed, adjusted to national energy balances and transformed into time‐variable emission factors. A case study demonstrates that CO2 emissions of a building determined on an annual basis differ significantly from those calculated using dynamic CO2 factors. The adaption of these factors to the specific case reveals a potential for emission reductions of a building's heat supply around 12 %.