Impact of dynamic CO₂ emission factors for the public electricity supply on the life-cycle assessment of energy efficient residential buildings

Climate change and its effects are the reasons for the energy transition in Germany and lead to an increasing exploitation of renewable energy sources. At the same time, energy efficient buildings reduce the heat demand significantly and allow for the operation of electricity based heating systems. With the aid of dynamic CO₂ emission factors, the life-cycle assessment (LCA) for buildings can be adapted to reflect the fluctuating nature of renewable energy sources and the dynamics of heating power demand during the use phase more precisely. A case study using dynamic building simulation and static as well as dynamic emission factors for the year 2017 shows deviations of 3.4 % in the building's GHG emissions. Furthermore, two emission factors for 2030 and 2050, which reflect the national 80 % carbon dioxide reduction target, are developed and applied to the case study. For these emission factors, the overall building's GHG emissions decline drastically, whereas the deviation between the LCA using static or dynamic emission factors increases significantly. It can be seen that the application of a more dynamic approach for LCA adds substantial value to the investigation. However, further investigation on a broader set of dynamic input parameters for the LCA of energy efficient buildings seems to be reasonable.