Embodied carbon: the key actions to address it

Climate change poses significant decarbonization challenges to the real estate industry as it is responsible for 39% of global carbon emissions. The building sector must play its part in addressing this climate emergency. This net zero journey starts by considering the entire life cycle of buildings to set an inventory of the emissions sources and how they can be reduced. Unlike operational carbon, which can be reduced through energy efficiency measures and using more renewables, embodied carbon is locked into buildings. The World Green Building Council estimates it could account for half of the entire carbon footprint of new construction by 2050.

According to the European Commission (2020), embodied carbon relates to “the greenhouse gas emissions associated with the non-operational phase of a project, namely the emissions released through extraction, manufacturing, transportation, assembly, maintenance, replacement, deconstruction, disposal, and end of life aspects of the materials and systems that make up a building (cradle to grave).”

Embodied carbon is crucial in understanding the full carbon footprint of a building, especially as operational carbon decreases due to more efficient designs and renewable energy. This blog will explore the different actions that can be taken to effectively reduce this embodied carbon. From reusing buildings and choosing sustainable materials to optimizing the design process and advocating for regulatory changes, this article outlines a practical approach to reducing the environmental impact of both new and existing built environments.

From lifecycle analysis to sustainable materials

The first step in dealing with embodied carbon is to undertake the Life Cycle Assessment of existing and new buildings. This analysis is critical for measuring and keeping track of embodied carbon, enabling action at every stage: 

• In the production stage, embodied carbon is primarily associated with the raw materials supply, their transportation, and the manufacturing processes involved.
• During the construction stage, embodied carbon continues to accumulate through the transportation of materials to the site, and the construction and installation processes. 
• The operation and use stage contributes to embodied carbon through activities such as the ongoing use of the building, regular maintenance, repairs, and the replacement or refurbishment of components. 
• Stakeholders also need to consider embodied carbon at the end-of-life stage, when the building is demolished. This includes accounting for the deconstruction of the structure, transportation of materials, demolition activities, and the processing and disposal of waste.

Optimizing a building’s carbon footprint over its lifetime involves balancing between reducing operational emissions and increasing embodied carbon to enhance the asset’s energy performance. 

To go deeper: What data is available for conducting a building LCA (Life Cycle Assessment)  in Europe?

Embodied carbon in new buildings

According to a report directed by CRREM, the construction of new buildings accounts for up to 70% of embodied carbon. This percentage split between the construction, transportation, and demolition of building materials. However, the construction of new materials contributes to the largest share (83% of emissions), causing the embodied carbon of new buildings to exceed the operational carbon emissions.

To reduce these emissions, the RE2020 in France introduces requirements throughout the whole life cycle of a building. Among its three main objectives, RE2020 encompasses reducing the carbon impact of new construction by 2031, where the maximum threshold in kgCO₂/m² will be lowered by more than 30% compared to the current reference level.

Embodied carbon in existing buildings

Improving existing buildings through efficient retrofitting to reduce carbon emissions. Over their lifetime, these buildings undergo refurbishments and renovations. These processes contribute to approximately 33% of carbon emissions due to embodied carbon – a different split between embodied and operational compared to new constructions. Existing buildings are not often energy efficient, but targeted retrofits can help reduce operational emissions, lowering their overall carbon footprint. 

The payback approach allows the industry to calculate how many years it will take for the added embodied carbon from a building to be offset by the operational carbons. For significant retrofits, this payback approach can take up to 15 years. 

Read more: How to address the challenges of embodied carbon.

Building better

The first step in addressing embodied carbon is to build more efficiently from the outset. In addition to implementing measures in new and existing buildings, it is crucial to prioritize material efficiency and structural optimization in design. This will ensure that every material choice contributes to a more sustainable, low-carbon future in the built environment. For example, modular construction can reduce energy use by up to 67% compared to traditional methods.

Carbon accounting in real estate: A guide towards a common definition of a building’s carbon footprint.

Retrofitting: reusing and recycling buildings 

When: during the operation and use stage.

Why: retrofitting strategies by improving existing structures rather than constructing new ones offer a straightforward solution to tackling embodied carbon in buildings.

A 2023 report from Build Change analyzed over 300 case studies and found that retrofitting homes to withstand disasters can reduce embodied carbon emissions by 68% compared to new construction. Not only is retrofitting more carbon-efficient, but it also avoids the need for post-disaster rebuilds, which can be resource-intensive and costly. Additionally, retrofits are more cost-effective in the long run, allowing for substantial savings over time while contributing to a more sustainable and resilient built environment. 

Different retrofitting measures can be implemented when reusing buildings to enhance energy efficiency and reduce embodied carbon. For instance,  limiting glass-covered surfaces is crucial as it helps reduce heat gain and energy consumption. Another example is replacing existing glazing with models that better filter solar radiation and adding solar protection like blinds or shutters, further optimizing energy performance. Solutions also include using free cooling or night-time ventilation – which involves cooling the building by bringing in cooler outside air during the night. It can significantly reduce reliance on air conditioning, leading to substantial electricity savings.

Retrofitting: 5 reasons why you shouldn’t overlook it.

Choose low-carbon concrete mixes 

When: during the construction phase of a new building. 

Why : cement, which that strengthens concrete, is produced by burning limestone in kilns at extremely high temperatures. This process typically relies on powdered coal or natural gas as fuel, consuming vast energy and releasing significant CO₂ emissions. 

Concrete accounts for 50-85% of the embodied carbon in any building project, highlighting the need for more sustainable construction practices. Low-carbon concrete is designed to have a significantly reduced carbon footprint compared to traditional concrete. It represents therefore a more sustainable option for construction projects. Advancements like self-healing concrete, supported by initiatives such as the GCCA (Global Cement and Concrete Association), further enhance the durability and sustainability of building materials. 

Opt for less carbon-intensive material 

When: when retrofitting existing buildings or during the construction stage of new buildings. 

Why: selecting more sustainable, lower-carbon materials is crucial in reducing a building’s embodied carbon footprint. Opting for less carbon-intensive materials can significantly diminish the overall environmental impact of construction. This approach implies choosing materials with lower embodied carbon and reducing the quantities of high-emitting materials, such as concrete and steel, which are traditionally used in large volumes. The careful selection and reduction of these materials can lead to substantial reductions of embodied carbon. 

Additionally, the increasing development of alternative structural systems and innovations facilitate the built sector’s decarbonization. This is the case of mass timber (a family of engineered wood products known for their strength, durability, versatility, and sustainability) or NGX insulation (which can help reduce greenhouse gas emissions and delivers a greater than 80% reduction in embodied carbon of the product)

Prioritize the reuse of materials and products

When: both in new buildings and retrofits, both in the construction and end-of-life stages of a building.  

Why: building materials represent a critical focus for reducing a building’s carbon footprint. Two key strategies are retention and reuse, which avoid the introduction of new carbon by preserving existing structural elements. Targeting high-mass elements and assemblies—such as the sub-structure, super-structure, and walls—can lead to significant carbon reductions. Some measures, such as incorporating recycled aggregates into concrete mixes, can also lead to substantial carbon reductions. Ultimately, prioritizing a circular economy by sourcing building materials locally further lowers embodied carbon, creating a more sustainable construction process.

According to RICS, 3.3 million tonnes of CO could be saved annually in the UK by reusing construction materials currently treated as waste. For instance, materials such as steel are already highly recycled materials, due to financial value. However, the real estate sector must widen this practice to more materials. Even top-performing countries are still reliant on waste recovery techniques and recycling. Reusing key materials like cement, aluminum, or plastic could help reduce a vast amount of emissions.  

Close-up on Nooco, french leader for Life-Cycle Assessment 

Nooco, acquired by Deepki is a SaaS platform, expert on LCA (Life-Cycle Assessment), and a solution designed for more transparency on the carbon indicator in construction projects. Elements like the superstructure, foundation, plumbing, facades, and finishes can contribute significantly to a building’s carbon footprint. Nooco’s goal is to help real estate players visualize the impact of these elements and implement measures to reduce embodied carbon in buildings. Nooco’s detailed Life Cycle Assessment highlights improvement areas and helps in selecting the best product alternatives or rethinking the entire project to make more sustainable choices. Builders, asset owners, operators, and manufacturers can measure and optimize the environmental impact of their new-build, renovation, or operation projects. 

Deepki acquires Nooco, VINCI Energies’ subsidiary specialized in embedded carbon measurement.

Addressing embodied carbon requires a strategic approach focusing on key actions throughout the lifecycle of buildings. The industry must prioritize material efficiency and structural optimization from the start to reduce embodied carbon. Implementing a Life Cycle Assessment helps identify and minimize carbon impacts at every stage, from production and construction to end-of-life.

Key actions include selecting low-carbon materials, adopting modular construction methods, retrofitting existing buildings rather than new builds, and reusing materials. Tools like Nooco, a Deepki solution, can enhance these efforts by providing detailed insights into a building’s carbon footprint, enabling more informed decisions. By integrating these practices, the real estate sector can make significant strides in reducing embodied carbon and moving towards a more sustainable future.