The GHG Emission Timeline – Integrating sustainability assessment into the early building design stage

To address the challenges of integrating sustainability assessment such as life cycle assessment (LCA) in the early building design stage, we propose a new concept: The Greenhouse gas (GHG) Emission Timeline. The concept is derived from researching robustness assessment methods and personal experiences from teaching. Rather than aggregating environmental aspects into a single number, with the Timeline we want to highlight the temporality of GHG emissions in the context of ongoing transformation processes. Similarly to the previously proposed Material Pyramid for comparing the CO₂ footprint of different materials, the Timeline is a pedagogical tool to visualize quantities, dynamics, and uncertainties aiming to provide a common ground for discussing sustainability in the early building design stage. The Timeline is compiled in a few simple steps with readily available resources. Hence, it does not need prior expert knowledge. The concept, as well as the first application examples of the Timeline from an architectural design studio at ETH Zurich are presented and discussed. By using GHG emission calculations for the compilation of a historic timeline, students created new lenses that addressed sustainability from a holistic viewpoint beyond GHG emissions.