Chapter 3
3.1
Circular Design Tools and Strategies for Planning and Decision-Making
3.2
Upstream Design Choices Are Key to Tackling Carbon Early
3.3
Building Less by Prioritising Renovation and Use of Existing Buildings
3.4
Focusing on End-of-Use, Not End-of-Life, to Avoid Landfill
3.5
Design for Disassembly and Modular Construction
3.6
(Re-)Use of Secondary Materials
3.7
Recycling Only as a Last Resort
3.8
Circular Strategies in New Buildings to Avoid Embodied Emissions

Circular Strategies in New Buildings to Avoid Embodied Emissions

In cases where new construction is required, design strategies can be used that reduce the amount of material used and that prioritise the use of locally sourced, circular and bio-based materials with low embodied carbon. These materials can be used to build larger-scale, adaptable structures that align with the principles of the circular economy.

Adopting Circular Strategies in the Material Manufacturing and Design Phases

Construction practices based on “design for disassembly” can promote adaptable structures that make materials easily recoverable.

When new construction is necessary, it can incorporate circular design strategies that reduce the amount of material used. Decisions about material selection – such as choosing low-carbon materials (whether bio-based or reclaimed) – will greatly avoid the need for extracting and using non-renewable virgin raw materials. Additionally, construction practices based on design for disassembly can promote adaptable structures that make materials easily recoverable for re-use at the end of a building life.

Promising technological developments are emerging for cements and binders derived from the direct capture of CO2 emissions that are generated at power plants and other industrial smokestacks (Cao et al. 2021) (see chapter 5). The decarbonisation potential is huge: if future building materials were derived from carbon capture, then even new buildings could potentially be carbon negative. If carbon-intensive materials (concrete or metals) need to be used, many strategies in the material processing and design phases can greatly reduce embodied carbon:

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Designing more efficient structural systems (e.g., standardisation of components, using mechanical joints instead of chemical joints) for ease of disassembly.

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Pre-fabricating components off-site to avoid waste and construction emissions. This can involve using factory-controlled methods that optimise material use and enable a component to be disassembled and reassembled into a future life cycle instead of being discarded. In some cases, off-site construction has reportedly reduced waste by up to 100 per cent (Chen, Feng et al. 2022).

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Making improvements during the production phase, such as electrifying (with renewable sources) as many processes as possible, and improving the mixtures for concrete and cement.

Selecting Locally Sourced, Circular and Bio-based Materials with Low Embodied Carbon

Innovators are working to increase the market share of low carbon and bio-based materials.

For the selection of new building materials, innovators are working on two major fronts to: 1) reduce the emissions of conventional building materials (see chapter 5), and 2) increase the market share of alternative building materials, such as reused and recycled materials as well as local, low-carbon solutions and bio-based materials (see chapter 4). Shifting from non-renewable to circular materials may help alleviate environmental stress from depleting raw mineral-based materials and promote circular flows of agricultural and other wastes (Churkina et al. 2020). (See chapter 4).
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Advancements in bio-based material systems present opportunities to expand to multi-story construction, including adaptable structures that could support design for disassembly. These kinds of structures may offer the potential to sequester carbon during the material production, construction and use phases (John et al. 2009; Robertson, Lam and Cole 2012; Laguarda-Mallo et al. 2014; Keena et al. 2022). These benefits of a shift to bio-based materials are discussed in the next chapter.

Summary

Key design strategies to improve circularity in buildings

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Build less, and build with less: Promote adaptive re-use and conservation of existing buildings to extend their lifetime. For new buildings, promote lightweight construction, using fewer materials, and mandate longer lifespan estimations.

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Use performance-based building codes for embodied carbon, which facilitate upstream design strategies to design out waste and tackle carbon early. Performance rather than prescriptive-based building codes would be supported by whole life-cycle thinking and analysis.

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Promote evidence-based material selection and awareness among building professionals of alternative low-carbon construction materials and components (both new and secondary materials) early on, to reduce long-term waste.

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Promote selective deconstruction at the end-of-use phase, prioritising careful dismantling over demolition to support material recovery of building components and materials.

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Design for disassembly and modular construction: New buildings should be designed for disassembly and should use modular construction to enhance longevity and enable dismantling, thereby reducing expended embodied carbon.

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Accelerate digitalisation of buildings to support waste diversion. Building information modelling and/or building passports can be used to monitor and control material use and to alert recycling companies of incoming end-of-use materials. Digitalisation can also facilitate assessing the quality of secondary materials before they re-enter the marketplace. Encouraging digitalisation in the construction process, especially for institutional and public buildings, will lead to a market transformation and facilitate the inclusion of these technologies in smaller buildings such as houses.

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