Chapter 2
Embodied versus Operational Carbon Emissions in Buildings
Embodied Emissions from Extracting and Producing Building Materials
Embodied Emissions: From End-of-Life to Re-Use and Recycling
Implementing a Whole Life-Cycle Approach to Building Materials
The Whole Life-Cycle Approach: Pathways for Decision-Makers
Strategies Towards a Building Materials Revolution: “Avoid-Shift-Improve”

Figure 2.8 Decarbonizing buildings and construction through
the Avoid-Shift-Improve approach

Adapted from PEEB 2021a.

Strategies Towards a Building Materials Revolution: “Avoid-Shift-Improve”

To decarbonise building materials by 2060, we must urgently support solutions across all major material types simultaneously.

The transition to sustainable, low-carbon materials will revolutionise the way we construct cities, infrastructure and buildings. To achieve a 40 per cent reduction in embodied carbon by 2030 – and completely decarbonise building materials by 2060 – we must immediately support viable solutions across all the major material types simultaneously.

Transitioning to a low-carbon future requires avoiding new raw material extraction of materials. If buildings are designed for circular disassembly and reassembly, they technically become material banks at the end-of-life. To reduce embodied emissions, non-renewable resources such as concrete and steel need to be obtained from recycled or reused sources wherever possible. This should be complemented by a shift towards renewable, bio-based products if practical. In sum, a revolution in building materials requires: 1) dramatically reducing emissions from conventional (non-renewable) building materials, and 2) accelerating growth in alternative (renewable) materials.

Based on this understanding, the actions needed to reduce embodied carbon across the whole life cycle of buildings and construction can be clustered into three main strategies, using the “Avoid-Shift-Improve” framework (Programme for Energy Efficiency in Buildings [PEEB] 2021a) (see Figure 2.8):

AVOID waste, build with less and improve circularity through better design and decision-making. This includes using resource-efficient design, extending the lifetime of buildings, and “doing more with less” through holistic design and circular economy strategies that design out carbon from the start. It also means prioritising the use of recycled, secondary and reused materials, which requires design for disassembly and the re-use of buildings and components. (See chapter 3.)

SHIFT to renewable, bio-based building materials to reduce demand for primary extraction. This includes greater use of agriculture and forestry by-products. Rather than relying on virgin forests for materials, it requires using wood and timber harvested from lands that were once used for agriculture and implementing sustainable management and afforestation practices. (See chapter 4.)

IMPROVE conventional building materials through decarbonisation efforts, including through energy and material efficiency and the use of renewable energy in production. Materials made from primary sources should be produced using best available technologies and electrified processes, and end-of-use recycling and re-use should be prioritised. (See chapter 4.)

Box 2.1
Provides an overview of how decision-makers can adopt a whole life-cycle approach and use these three strategies to transition building materials to a low-carbon future.

Figure 2.9 Transitioning building materials to a low-carbon future

Source: Ciardullo, Reck and Dyson 2023. Global emissions from Zhong et al. 2021; OECD 2022a. Material mass and recycling rates from: Miatto et al. 2017 (cement); Cullen, Allwood and Bambach 2012 (steel); International Aluminium Institute [IAI] 2020; Westbroek et al. 2021 (glass); Miatto et al. 2022 (masonry); Geyer, Jambeck and Law 2017 (plastics); Food and Agriculture Organisation of the United Nations [FAO] 2020 (timber).

Transitioning building materials to a low-carbon future

Due to the integration of many materials in building systems, it is essential to support efforts to reduce carbon emissions across all building materials.

Across all climate types, buildings will continue to rely on a broad range of both conventional and emerging material streams. However, moving towards a low-carbon future requires a cumulative change in how building materials are used and sourced, across the full spectrum of materials. It requires holistic application of the “Avoid-Shift-Improve” strategies promoted in this report to prevent overuse of extracted raw materials and to facilitate the shift from non-renewable to renewable and secondary sources.

Figure 2.9 shows how these actions would change the type of building materials used and their sourcing. A consistently adopted whole life-cycle approach coupled with the decarbonisation of primary emitters such as concrete/cement and steel would dramatically reduce embodied emissions across new and existing buildings.