A framework for 1.5°c-aligned GHG budgets in architecture

A methodological framework is presented for integrating 1.5°C-aligned greenhouse gas (GHG) budgets into architectural practice. Responding to the urgent need to decarbonise the built environment, this practice-oriented approach is based on the Carbon Risk Real Estate Monitor (CRREM) and the Science-Based Targets initiative (SBTi). The framework enables GHG budgets to be set early, requiring only a functional brief and target completion year as inputs. It establishes absolute GHG budgets per m2 and completion year for eight core building usage categories, allowing the early integration of climate targets in design processes. Mixed-use buildings are addressed through the area-weighted allocation of usage-specific budgets. Although developed for the European context, the framework can be adapted to other countries. The proposed 1.5°C-reduction pathways are compared with national frameworks such as France's RE 2020 and Denmark's BR 18, as well as with 20 recent mixed-use projects from a large German architectural practice. Achieving 1.5°C alignment will require halving GHG budgets roughly every seven years, highlighting the need for transformative change in architectural design and construction. Limitations include the use of global embodied carbon benchmarks and the assumption of functional stability over a 50-year reference study period.