Our built environment is becoming increasingly efficient, and we’ve made tremendous headways to raise awareness and address operational carbon emissions, but the focus is shifting. Without enough attention paid to reducing embodied carbon in our built environment, breakthroughs in climate change mitigation will be almost impossible to realize.
Growing commitments toward ambitious greenhouse gas reduction goals bolster global momentum toward reaching a net-zero, resilient future. So, where does Embodied Carbon (EC) fit into the picture? We know that embodied carbon emissions in new constructions refer to the carbon dioxide emissions that occur during resource extraction, manufacturing, construction practices, and transport of materials throughout the whole lifecycle of a building or infrastructure project. Essentially, these emissions happen before we even turn on a light switch or crank up the heating in a new building. Be that as it may, operational emissions, not embodied carbon, have underscored climate action in our built environment. But consider this, EC will account for a big chunk of the overall carbon emissions ‘pie’ of new construction by 2050.
The Global Emissions Pie
At a glance
Our built environment puts the most pressure on our natural resources and takes center stage in the fight against runaway climate change. 70% of our global energy consumption and carbon dioxide emissions come from cities, even though they only occupy 3% of the Earth’s surface. As if we didn’t have enough to worry about, these emissions are set to double by 2050 .
The story so far
Contractors and developers know addressing greenhouse gas emissions from material extraction and construction is paramount. Yet the question remains whether emissions are being addressed appropriately. In effect, are we gaining ground where we need to be? For years, operational carbon (carbon emissions from a building once it is already in use) has been the main target of emission reduction strategies. But since we expect embodied carbon will contribute over 50% of these total emissions in construction between now and 2050, can we remain on the same course? This statistic reflects a need for structural engineers, architects, and developers to shift focus. They can be major players in embodied carbon mitigation strategies and pioneers in sustainable building design.
Ten ways to accelerate the transition to net-zero
10% of annual global emissions are linked to the embodied carbon of materials. Regardless of the apparent implications, there is insufficient research on embodied carbon in the building sector. This means that potential initiatives to mitigate the problem will be varied. As we so often do, we’ve thought hard and researched the Top 10 ways to achieve embodied carbon reduction in our built environment and would love to share these with you:
1. Reducing Embodied Carbon through material selection
As you may have already guessed, a building’s overall embodied carbon is linked to the material composition of the products from which it is made. Reducing EC through material selection is a particularly common solution today. It puts maximum power in the hands of architects, engineers, and designers to intervene early in carbon-intensive practices. Following principles of sustainable design and lean construction, designers can minimize the use of high-carbon content materials from as early as the design stage. Depending on the project, designers can reduce the number of carbon-intensive materials (steel, concrete, glass) or introduce carbon-neutral/carbon-positive raw materials. Some carbon-friendly structural materials for use in buildings include:
- Mass Timber
- Recycled Plastic Cladding
- Low carbon concrete
It goes without saying that designing better would be the most sensible thing. Yet, procurement, economic, technical, and governance barriers that plague the construction industry often put a spanner in the works of good design. Simply put, the industry is worn and stuck in its ways. More intelligent and sound design practices and appropriate choices made at this early stage can be significant factors in embodied emissions mitigation. We know that not all functional designs are necessarily good. So, we want to see more effective and less fragmented decision-making throughout a project using a systematic analysis of all different design stages to assess carbon emissions and design for low-carbon buildings.
You would also be quite right in thinking that saying ‘design better’ raises more questions than it answers. The frustrating reality is that no solution is perfect and it is the small steps taken toward new means at an early stage that can contribute significantly to the industry’s next big leap. So what are some common, carbon-conscious design choices that engineers can make?
- Analyse and select carbon-friendly and functionally equivalent structural system alternatives to conventional concrete/steel-based frames. The selection of structural systems (e.g. façade fenestration, structural system, servicing strategy, prefabricated elements, post-tension structure) determines the level of GHG emissions in a building’s lifecycle, accounting for 15% of total material emissions. So, adopt the lowest carbon system at this early phase. Selecting a structurally equivalent wood-framed building as opposed to a comparable concrete structure would reduce operational emissions and embodied emissions by as much as 45% 
- Assess your preliminary carbon footprint and carbon impacts by taking a holistic look at your project, primary building materials, floor area, the number of expected occupants, etc.
- Study the carbon efficiency of alternatives with the help of an Embodied Carbon Calculator.
- Use BIM-compatible tools to assess Carbon footprint at the early stages of a project lifecycle.
The lack of design-integrated tools and process guidelines for low-carbon building design at the concept/design stage is setting the industry back. While there are many Building Energy Software Tools out there, few inform the early stages of design where some of the most impactful decisions are made. That is a space that CalcTree is keenly watching!
Are you interested in a platform that can smooth out design workflow, avoid project roadblocks and unlock a path to innovative and sustainable design? Sign up with CalcTree today!
3. Tools, Methods & Methodologies
Existing and emerging tools and technologies used in the construction sector can benefit from integrating embodied carbon assessments into their workflow.
Building Information Modelling (BIM):
BIM is a knowledge resource for information in a construction project that allows decisions to be made during the project’s life cycle from conception to demolition.
We can estimate embodied carbon by coupling EC assessments with BIM, either with an information hub or simulation tools. The 7D BIM by Cartwright Pickard is an example of a BIM plug-in that can predict the whole-life cost and whole-life carbon of buildings giving architects and engineers more power over their decision-making during design.
Building rating systems: BREEAM, LEED and Green Star are all global building rating systems that have so far recognized embodied carbon mitigation as part of minimizing a building’s environmental impact. Building projects aim to gain certification because it means that they have been independently verified as sustainable and have demonstrated environmental stewardship. Holistic rating tools within a comprehensive advocacy agenda can incentivize the race toward net zero. Keen to learn more about new tools, methods, and smarter engineering designs? Click here!
4. Sustainable refurbishment
Big opportunities for embodied carbon reduction and mitigation can lie with the upkeep and renovation of existing buildings and infrastructure. Refurbishment projects can include:
- Maintenance & Repair
- Improving energy efficiency
- Upgrading building functions
While adding new materials or disassembling old ones can increase the embodied carbon footprint, refurbishments can reduce operational carbon. Research has shown that it is better to bring a building up to modern standards, given that the EC of an average refurbishment project is one-third of that of a new building.
5. Think circular: preserving embodied carbon through re-use and recycling
There has been a global shift towards circular economy initiatives in the construction sector involving material reuse, recycling, and remanufacturing to reduce waste and preserve the embodied carbon already in the system. Embodied carbon can be held by converting waste, bioproducts, and used materials into building materials. Strides have been made worldwide to implement recycled materials into building projects. Recycled glass, denim, plastic bottles, and reclaimed building materials are reused resources that can have a sizeable impact on embodied carbon preservation.
6. Embodied carbon mitigation through better construction techniques
Prefabricated and modular construction are emerging as popular design methods in the construction sector. Prefabricated buildings consist of components and elements manufactured in remote factories, transported on-site, and assembled into buildings. Studies have shown that productivity will substantially improve by increasing the proportion of prefabricated elements in a construction project. This will result in faster construction, lower emissions, less waste, noise, disruption, and lower unit and operational costs. A holistic approach combined with other strategies (i.e., using low embodied carbon materials) in on/off-site construction practices can significantly impact EC reduction.
The construction of the world’s tallest modular building in London took prefabricated construction to new heights. It claimed to have reduced embodied carbon by a whopping 40% when compared to traditional construction methods.
Changing national building codes and standards to address embodied carbon are matters of government policy and industry policy. So is an incentivizing investment in carbon-friendly construction materials and encouraging industry clients to request low embodied carbon materials and outcomes. Implementing and revising policy by governments can have wide-reaching impacts on EC reduction. For example, creating a new or amended design code that includes definitions and guidelines on low/zero carbon materials and systems would drive designers to incorporate or comply with it. Standardizing projects to meet embodied carbon targets would allow designers, contractors, and clients to commit to these initiatives. There are many other government regulations, industry bodies, and stakeholders within construction sectors that can enforce strategies for EC reduction. Whether it be financial incentives, research investment, carbon awareness communication, and targets, these policies will have the most significant reach in tandem with other mitigation strategies.
Societal changes, perceptions, and awareness are all critical factors in driving action against climate change. The same can be said on a more localized level concerning action towards embodied carbon. Engaging leaders in supply, design, client, and contracting in embodied carbon sessions and summits and providing education about reducing embodied carbon is critical to ensure support for appropriate EC mitigating strategies. This can lead to industry-wide changes and adoptions of low-carbon initiatives and it would generate demand, incentivizing the development of design tools that will evaluate low-carbon design solutions. These tools will evaluate our designs' impacts and create a demand for buildings and projects with sustainable credentials. The global conversation around the necessity of reaching net-zero embodied carbon can spark big leaps in the industry; we just need to adopt a common language, principles, actions, and definitions to yield market action.
9. Life Cycle Assessment (LCA)
EC assessment falls within a broader discipline called Life Cycle Assessment (LCA). LCA in construction involves an evaluation of environmental impacts during all stages of a building’s life cycle, from material extraction to construction, operation, and beyond. The scope and LCA stages must be defined and known when tracking embodied carbon. The scope of a project, whether it is a large commercial building or a single-story building, has a significant impact on embodied carbon figures. The larger the project’s scale, the more likely it will be responsible for more embodied carbon. Managing embodied carbon within an LCA framework could potentially involve:
- Incorporating requirements for reporting, reducing, and offsetting embodied carbon emissions
- Setting or adhering to emission reduction targets
- Calculation and disclosure of LCA results for new buildings
The use of local raw materials would benefit local or national economies and drastically reduce transportation emissions, already making up almost a quarter of all CO2 emissions in the construction sector. The majority of transport emissions are produced by transporting construction materials to the site.
The construction industry accounts for nearly 40% of global energy and GHG emissions . We know that almost half of those emissions will come from Embodied Carbon, yet not enough time, attention, and research has been dedicated to understanding the best ways to mitigate it. It has become clear that operational carbon is just one piece of the carbon footprint puzzle. The next frontier to decarbonize our built environment will be to appropriately address embodied carbon. As you might have noticed, each of the Top 10 ways (listed above) to reduce embodied carbon are inextricably connected, showing us that there is not only a diverse range of approaches to address the problem but that a pluralistic solution must be found since no strategy can effectively stand on its own.
Since decisions impacting embodied carbon emissions are often during a project’s design stage, this is where CalcTree might be able to help.
-  United Nations Sustainable Development. 2022. Cities - United Nations Sustainable Development Action 2015. Available at: https://www.un.org/sustainabledevelopment/cities/
-  Pomponi, F. and A. Moncaster (2016). "Embodied carbon mitigation and reduction in the built environment – What does the evidence say?" Journal of Environmental Management 181: 687-700.
-  World Green Building Council (2019). “Bringing Embodied Carbon Upfront”. WGBC Report: 1-67