Source: Carbon Cure, 2024
The London Plan 2021 is ambitious in its goals for reducing carbon emissions in the built environment. However, the policies surrounding carbon reduction - especially when it comes to Embodied (Embedded) and Operational carbon - can sometimes be at odds with each other. GJA aims to balance planning policy with innovative design solutions.
The Dilemma of Embodied vs. Operational Carbon
At the core of the London Plan is a focus on both embodied carbon - the carbon expended in the production and construction of materials - and operational carbon - the energy used to run a building throughout its life. For GJA, this distinction is fundamental when tackling sustainability in residential developments.
Embodied Carbon: This refers to the carbon already "spent" in the materials and construction of a building. For example, the carbon required to extract raw materials, manufacture products, and construct a building. Demolishing an existing building removes this embedded carbon, but replacing it with new construction materials generates new carbon emissions.
Operational Carbon: This is the carbon produced during a building's use, related to energy consumption for heating, cooling, and other operational needs. Ideally, new buildings should be more energy-efficient than their predecessors, thus lowering operational carbon emissions over time.
The challenge is that these two types of carbon are often in direct conflict. For example, in the case of a building with outdated but energy-efficient brickwork, demolishing the structure might remove the embodied carbon of the bricks but require significant new materials that increase operational carbon. Meanwhile, trying to upgrade old materials to be energy-efficient may end up consuming more energy than is saved in the long term.
The Challenge with Local Authority Policies
A key issue with these policies lies in their inconsistency across different local authorities. For example, the City of Westminster has a strict policy of not allowing the removal of embedded carbon, particularly in relation to heritage materials like 19th-century brick walls. These old materials are often thermally inefficient, meaning they require more energy to keep the building operationally efficient.
In such cases, trying to retain the original fabric can lead to higher operational carbon costs, because significant energy would be needed to insulate and modify these materials for better thermal performance. Conversely, repurposing and recycling materials can return carbon to the system at zero additional cost, making it possible to create a more efficient and sustainable development in the long run. GJA’s solution has been to carefully assess these contradictions and use a whole-life carbon approach.
Source: TATE & CO, 2024
Whole Life-Cycle Carbon (WLC) emissions encompass all carbon emissions associated with a building throughout its entire lifespan—from material production and construction to operation, demolition, and disposal. Conducting a WLC assessment offers a comprehensive view of a building’s environmental carbon impact. GJA, therefore, examines both embodied and operational carbon at every stage of all projects to ensure that any decisions made regarding the retention of materials or demolition are in the best interest of the building's long-term carbon footprint.
Whole Life Carbon Analysis at Passmore
One of GJA’s recent projects, on Passmore Street, serves as a case study in how conflicting policies can be navigated. The project’s original design required the retention of party walls, but this would have led to very high operational carbon costs. These walls were part of the original fabric, but they were made from materials that weren’t thermally efficient. Retaining them would have meant investing large amounts of energy into insulation and modifying the structure to meet sustainability goals.
By dismantling the party walls and repurposing the original bricks, GJA significantly reduced the operational carbon costs of the project. The repurposed bricks allowed for the construction of energy-efficient materials, thus reducing the time required for the project and minimizing the temporary carbon emissions associated with construction. This strategy resulted in a 22% reduction in operational carbon over the 40-year lifespan of the building, contributing to the London Plan’s goal of a 35% improvement in operational carbon.
Although the policy required the retention of original fabric, GJA successfully negotiated with the local authority to allow the replacement of the party walls based on the whole life carbon analysis. This example highlights a key issue: while the London Plan encourages the retention of existing structures, a whole-life carbon assessment, which is not currently required at the planning stage, could provide a clearer picture of how to align these policies and achieve better outcomes for sustainability.
The Need for Policy Alignment at the Planning Stage
Currently, local authorities - especially in densely populated areas - are reviewing and updating their policies to address the contradictions between embodied and operational carbon. GJA works closely with sustainability counsellors who are aware of this shift, and are pushing for greater alignment of policies at the planning stage rather than only during the construction process. By integrating whole life carbon assessments earlier in the planning process, it would be easier to hit sustainability targets and ensure that the policies around embodied and operational carbon are harmonised.
At present, whole-life carbon assessments are only required for major projects, which typically include large-scale developments or luxury residences. However, GJA believes that these assessments should be applied more widely, even to smaller residential developments. The current approach often results in missed opportunities to reduce carbon early on, particularly in small-scale projects, where the process is more manageable but equally impactful.
The Future of Carbon Assessment in London
As the government continues to evolve its stance on carbon emissions and sustainability, particularly under the Labour administration, there is hope that the policies will become more unified and comprehensive. GJA’s commitment to sustainable architecture is underscored by a desire to help shape this future.
In conclusion, the conflicting policies on embodied and operational carbon present a notable challenge for GJA and other developers. However, by leveraging detailed analysis and a whole-life carbon approach, GJA effectively navigates these complexities to achieve meaningful reductions in both embodied carbon and whole-life carbon emissions. Collaborating with local authorities and advocating for policy alignment at the planning stage, GJA delivers thoughtful, efficient, and future-proof designs that prioritise sustainability without compromising innovation.
Notes
Image from Carbon Cure, ‘What is embodied carbon?’ published 22.09.2020, <https://www.carboncure.com/concrete-corner/what-is-embodied-carbon/>
Image from TATE & CO, 'What is a Whole Life Carbon Assessment?' published 2024,
Comments