The Challenge of Modeling Tracked Electricity Consumption in EPDs: An Example for Building Materials

In life cycle assessment, electricity consumption can be modeled with a “physical mix,” reflecting regional electricity generation and trade, or with a “virtual mix” based on guarantees of origin (GO). For environmental product declarations, modeling the electricity mix based on GOs is sometimes the preferred approach taken by program operators. However, this is currently only applied to foreground data, while background electricity mixes rely on databases typically providing physical mixes. This simultaneous use of mix modeling methods not only raises a consistency issue but also a double-counting problem, because renewable electricity claimed in the foreground by GOs can still be used in the physical electricity mix used in the background. We propose a first exploration of how the environmental impacts of building material production could change with a partially consistent virtual mix approach. In the foreground, we assume that material producers cover their electricity demand with renewable electricity tracked with GOs. In the background, only the remaining untracked electricity (residual mix) is left and applied where data availability allows. High variations are observed in the impact indicators climate change (biogenic, land use and land use change) and ionizing radiation. Our analysis is a first step towards more consistent electricity consumption modeling.