Figure 3.1 Opportunities to reduce carbon at each phase of the building life cycle
Decarbonisation requires a change in use across all building materials.
A circular economy for the built environment is rooted in design and decision-making (Keena and Rondinel-Oviedo 2022). Design decision-making during each phase of a building’s life cycle offers opportunities to reduce embodied carbon (see Figure 3.1). Key interrelated circular design tools and strategies include:
upstream design choices (for example deciding on what to build, form, layout, materials etc.), including building (with) less and building smarter;
selecting building materials and elements that have lower embodied carbon because they are either recycled/re-used or are inherently lower-carbon; and
end-of-use strategies to avoid waste and enable the re-use and recycling of materials and components.
These strategies must be considered in tandem. For example, re-using materials as much as possible is a good start, but there is a growing gap between the available supply of and demand for recycled materials (see chapter 5). Therefore, a next good step might be to replace high-carbon materials with low-carbon renewable materials, such as bio-based materials. However, it remains unclear how the scaling of biomaterials, such as wood and bamboo, will impact the ability of regional ecosystems to sequester carbon. Bio-based materials are low carbon in their processing and use, but this must be accompanied by sustainable forestry and farming practices (Keena, Duwyn and Dyson 2022) (see chapter 4).