Simplified procedure for defining science-based climate change targets for absolute sustainable building design

Authors
Sørensen, Lise Hvid Horup; Ryberg, Morten Walbech; Birgisdóttir, Harpa

Abstract
Quantification of environmental impacts of buildings through Life Cycle Assessments (LCA) has gained broad attention in the building industry in recent years and has helped identifying environmental hotspots and the most eco-efficient buildings and building materials. Today, we set targets for our buildings through a bottom up approach – benchmarking the buildings performance up against existing building LCAs. But is “more sustainable” sustainable? Bottom up benchmarks will not secure, that the building design is in line with the Paris Agreement goal of limiting global warming to 1,5 degree Celsius. Therefore, there is a need for evaluating building performances in relation to science-based absolute environmental targets. Here, we propose a simple procedure for determining the climate budget of a building project through a top down approach aligning targets with the global climate budget. The procedure involves defining the climate budget to the construction sector and further downscaling this to the level of the specific building. A number of downscaling steps are performed during this procedure, which involves important choices on how the allocation of the global climate budget to a specific building is performed. It is, therefore, very important to be transparent in communication of these choices and ideally seek a harmonization and consensus within the industry on how to perform the choices. The outcome of this project will be a CO2 budget per m2 for embodied impacts. This project will propose benchmarks on building level, which will provide the architecture, engineering and construction (AEC) sector with benchmarks that are actually based on global absolute targets for climate change. Hereby, the method can be used for designing buildings that are designed to be climate wise sustainable and, thus, actively contribute to a sustainable transformation of society and a realization of global commitments such as the Paris agreement on climate change.