The building sector is responsible for 40% of global CO2 emissions, and many policies have been introduced about the energy efficiency of buildings during their working life. However, little consideration has been given to the whole life of a building, from the production of materials to the disposal of old buildings. Here, Ms Judy Too and Dr Obuks Ejohwomu – with colleagues from the University of Melbourne – explain the need for new standards on the environmental impact of construction materials, and revised frameworks for estimating whole-life emissions.
- A lack of government policies addressing embodied emissions hinders efforts to reduce the construction sector’s whole-life carbon footprint.
- Policy recommendations for decarbonising the building sector include mandating Environmental Product Declarations (EPDs), implementing project-level carbon budgets, and whole building Life Cycle Assessment (LCA).
- A phased introduction will allow the construction industry time to gather high-quality emissions data on different materials.
The building sector is the single largest contributor to greenhouse gas (GHG) emissions, accounting for 40% of global emissions. In the UK, the building sector is responsible for approximately 25% of GHG emissions. Acknowledging the substantial potential for energy efficiency improvements to mitigate GHG emissions in this sector, the 2011 UK Carbon Plan prioritised the building sector as a key area of focus. While progress has been made in designing and operating energy-efficient buildings in the last decade, government policies have been lacking in mandating the assessment or regulation of embodied emissions from buildings – the GHG emissions generated during the production and transport of materials, and the disposal of materials at the end of a building’s life. For instance, although the UK National Building Regulation imposes minimum energy performance requirements for new buildings, it does not regulate whole life cycle emissions. Consequently, little to no progress has been made in reducing embodied emissions within the sector.
Key policy-relevant findings
Reducing emissions in buildings is a complex problem, requiring consideration of various overlapping factors. Moreover, stakeholders navigate a complex decision-making process and employ diverse strategies to achieve net-zero emissions in the sector. Against this backdrop, researchers from The University of Manchester and the University of Melbourne sought to investigate the challenges and opportunities associated with standardising approaches for carbon reduction in buildings. Notably, previous research from the University – with national and international colleagues – identified the lack of high-quality data and standardised metrics for whole-life carbon reduction as significant challenges to be addressed.
In light of this, we identified four key decision variables that should be considered when making decarbonisation decisions; namely whole life cycle energy, emissions, economy and exergy (4Es). While it is crucial to consider all these factors from a whole-life cycle perspective, our study revealed that current decision-making practices prioritise investment/capital cost over long-term environmental impacts. This discrepancy underscores the need to align decision-making practices to shift the focus from short-term goals to whole-life carbon impacts.
Here, we outline specific conditions and pathways for driving decarbonisation in the building sector, which will exert influence on market forces and lead to the gradual reduction in investment costs of low-carbon materials and technologies.
A five-year policy plan for the building industry
The UK’s Nationally Determined Contribution (NDC), made at the 26th Conference of Parties (COP26), commits to reducing the country’s emissions by 68% by 2030, necessitating rapid transformation. Our proposed policies encompass three main areas of action:
- Mandating Environmental Product Declarations (EPDs) for all materials
- Integrating whole building Life Cycle Assessment (LCA)
- Implementing project-level carbon budgets
Since these policies rely on the widespread availability of high-quality data, manufacturers should be mandated to produce EPDs for all materials. This will build the necessary knowledge infrastructure, while increasing awareness of the embodied carbon content of building materials. Responsibility for implementing these policies will lie with the Department for Levelling Up, Housing and Communities.
EPDs, as per ISO 14025, enhance accountability in the value chain and aim to streamline continuous market-driven environmental improvement of products. However, recognising that the market may not currently be fully prepared to meet such stringent requirements due to significant gaps in primary data, industry wide EPDs can be initially used to establish the industry average Global Warming Potential (GWP) for the materials in the short term (0-1 years).
As data becomes available, product-specific EPDs can be mandated (1-2 years). These EPDs often rely on secondary data sourced from generic life cycle inventory databases for their upstream phases. However, these databases often differ in their sources and regional specificity, leading to a lack of comparability, undermining the purpose of reporting. To address this, Product Category Rules (PCRs) should be updated to mandate the use of primary data for significant upstream processes that contribute to a substantial portion of a product’s embodied emissions. This will enable manufacturers to generate supply chain specific EPDs, transforming the role of EPDs beyond mere communication tools, and into valuable aids for procurement and reliable sources of data.
Consequently, a national database of embodied carbon limits for building materials, based on supply chain-specific data, should be established. This comprehensive database will empower decision-makers to take informed choices based on carbon performance, encouraging the selection of environmentally-friendly materials. Furthermore, PCRs should be updated to include reporting on life cycle stages beyond cradle-to-gate (e.g., use and end-of-life) to provide a more comprehensive understanding of the product’s overall environmental impact and ensure that all key emissions are appropriately accounted for. Successful implementation of this policy requires government intervention through mandates, and incentivising small and medium manufacturers through tax credits or grants. Collaboration with industry stakeholders, research institutions, and certification bodies will also be vital to provide the necessary expertise and support for effective implementation.
Our work also revealed that end-of-life treatment of materials and buildings is often overlooked. To facilitate comparisons across different product categories, a building scale approach relying on whole-building LCA should be adopted. Therefore, it is essential to update building code regulations to include the industry’s proposed Part Z amendment, which incorporates considerations for whole-life carbon impacts. This update will mandate whole-building LCA, shifting the focus from prescriptive emission limits to evaluating and optimising the overall performance of the building in terms of its environmental impact.
Setting project-level carbon budgets based on predefined boundaries and benchmarks aligned with sectoral carbon limits should be a mid-term target (3-5 years). These limits establish precise emission targets that building projects must meet, with enforcement mechanisms such as audits and monitoring systems in place to ensure compliance. By implementing such limits, projects are held accountable for their emission levels over the building’s lifecycle, thereby driving carbon reduction within the building sector. Moreover, this approach will shift the focus from material-level to project-level assessments, promoting integrated decision-making and collaboration among stakeholders. It provides a clear target and accountability framework for all parties involved, establishing a baseline for measuring the carbon performance of buildings and ensuring alignment with sustainability goals. This will incentivise the adoption of low-carbon materials and technologies, driving market transformation and research investment.
By acting on these recommendations, policymakers can lead a combined effort to balance environmental goals with economic considerations. To not do so, and continue to ignore the whole-life emissions of buildings, risks locking-in unsustainable buildings for decades. At a tipping point for global action on climate change, this is truly building a house on sand.
This article is based on research conducted with academic colleagues from the University of Melbourne – Professor Felix Hui, Dr Nilupa Herath, and Professor Emeritus Colin Duffield.
