Imagine paying the bill for a product even before you start using it and paying an additional fee after you finish using it. That is the embedded carbon ‘bill’ for new buildings. Embodied carbon in construction racks up the ‘carbon emission bill’ from the manufacture of building materials to their construction, and it keeps going during demolition! Aggregated across all construction projects, the magnitude of this ‘bill’ is astounding, accounting for 11% of the total carbon emission on the planet .
Since the World Green Building Council proposed the embodied carbon vision to reach net zero for all infrastructure by 2050, the construction industry is hungry to reduce embodied carbon. Achieving this required cutting down carbon dioxide emissions in the construction process and completing a carbon-friendly life-cycle from production through to the end of life. That is where smart engineering solutions come in, shifting the industry from traditional methods to smarter, simpler, and more environmentally friendly solutions.
Problem identification: Where does embodied carbon come from?
Let’s break down carbon sources from the building life cycle:
- Production stage: Mainly involves the manufacture and transportation of construction materials. The upfront carbon emissions coming from building materials are the greatest sources of embodied carbon. The two most common materials, cement, and steel across all their uses, contributed to 7 - 9% of global carbon emissions each .
- Construction stage: The function of heavy machines, excavations, and transportation are all activities for carbon emissions. Curing concrete is also a huge source of emissions. It is estimated that carbon capture and utilization for concrete production (CCU concrete) will reach 0.1 to 1.4 gigatons of carbon dioxide (CO2) by 2050 .
- Operation stage: The carbon emission in this stage is called ‘operational carbon’, as opposed to embodied carbon. It is operational emissions from gas, power, and heat during the operational phase of the building. It currently accounts for 28% of total global carbon emissions. However, the amount of embodied carbon is predicted to surpass operational carbon by 2050.
- End-of-life stage: The profile of carbon emitted during demolition is similar to the construction stage. However, the material wastage and processing is more like stage one: emitting more carbon through material transportation and processing.
- Beyond the lifecycle: This is the stage all engineers dream of, but not many projects achieve. At this stage, the building can achieve net-zero carbon levels, or even absorb carbon in the environment, giving the asset a negative carbon footprint for its entire life cycle. This happens due to the reuse or recycling of materials after the building is demolished. Emissions could also be counteracted by exporting renewable energy or using waste as a fuel source.
Solution brainstorming: What can engineers do to impact embodied carbon?
So now you know what's causing the problem. Let’s pinpoint where engineers can actually have a large impact on emissions.
Alternative materials: Obviously, from the amount of embodied carbon in steel and cement, engineers must look into other options with less of a footprint. Currently, timber is a prominent choice (for mid and low-rise buildings). You can discover more about the timber options in construction in our article Sustainability and Timber, Top of Mind and Leading Edge. Researchers are also already making moves in exploring more exotic materials to replace concrete, such as hempcrete. You can explore more about the magic of hempcrete in another CalcTree article here! Alternative construction technology: Traditional construction has been racking up the carbon bill for a long time, especially due to construction waste. New machines, new energy sources, better waste management, and new construction methodology, can be brought in to shift the industry to produce less carbon. Modular construction and drone surveying are some pretty cool examples of this to name a few. Carbon-saving designs: For structural engineers, the shape of the facade and roof, the thickness of walls and floors, and other structural components all contribute to a building's embodied energy. Hence, optimizing those structures to have them lighter, more slender, and simpler is a prominent option to decrease carbon emissions in construction and save operational energy. One example of such a structure is the slim floor slab structures like Deltabeam.
Minimise waste: Currently, according to the Building Performance Institute report, 35% of buildings in Europe are more than 50 years old, meaning they’re at, or approaching the stage of needing repair, renovation, or demolition. Such structures are likely to release a massive amount of carbon during these processes due to old and carbon-intensive construction methodologies. So it’s critical that modern carbon-friendly buildings are attached with a life-cycle assessment from start to finish. The World Green Building Council already proposes the benchmark to complete the whole life cycle assessment approach for all buildings starting in 2025 .
Achieve negative net carbon emission: This is called a ‘Carbon Drawdown building’, which can absorb carbon from the environment during operation and stores more carbon than it emits. How is it possible? The key lies in the use of plant-based construction materials that naturally store carbon throughout their lifetime. A recycled building where its materials and components can be passed down to other infrastructure can also contribute to embodied carbon drawdown. However, this approach goes beyond the current aim of the World Green Building Council and governments.
Solution analysis: How can carbon-reduction solutions be applied for smarter engineering designs?
Let’s deep dive into modern engineering progress in tackling embodied carbon. You can also read about more solutions in our other article on The Decarbonisation Agenda
Carbon estimation and life cycle assessment:
The ability to estimate and quantify carbon footprint across the whole lifecycle using life cycle assessment (LCA) helps engineers identify major design problems driving up the carbon footprint and fix them. For example, let’s break down carbon emissions from the life cycle of a door (above picture). So, engineers can consider cutting down carbon emissions in the door from its critical stage, as observed, in its manufacturing or use stages. Solutions proposed could be using environmental-friendly materials in manufacturing or reusing the door after disposal.
LCA results for a portion of the building can also be scaled up to provide an overall estimate of the carbon footprint of an entire building. For example, by identifying the embodied carbon in a shallow foundation with poor soil conditions, engineers can optimize the foundation to be deeper with stronger soil on which to position the structure. In conjunction with the LCA metric, engineers can then perform a cost-benefit analysis on each option that considers embodied carbon. This is ideal, however, it’s worth noting that formalizing LCA numbers has been a hard task for a long time due to bureaucracy from international standards and legislative bodies.
The advancement of modeling techniques such as BIM, and Building Information Technology supports engineers in detailed designs, exact measurements, and cross-disciplinary collaborations. Hence, multiple countries have released environmental product declarations (EPDs) to detail how to calculate the embodied carbon throughout the material’s life cycle.
Otherwise, many software, design tools, and guidance are available to assist engineers in carbon conscience design methodology. Soon enough, engineers will be able to unify how we estimate carbon and apply it to all existing infrastructure.
Building materials - Timber:
Let’s look at the model of a 2000m2 building with 4 stories and 8 units. Increasing the usage of timber materials has the potential to greatly reduce carbon content. In some cases even results in zero or even negative total emissions!
Timber has always been a valued material in green constructions. Hence, from foundation to cladding and roofing, there will always be space for use of timber materials. And the right combination of these materials would result in negative carbon emissions, making it far easier to achieve ‘Carbon Drawdown Building’ status.
Even though there are limits in strength and maintenance, current technology is enabling the improvements of hybrid timber structures. As such, we’ve never been closer to achieving both high structural and high energy efficiency for tall structures.
Construction method, modular construction:
To redefine our construction process, modular construction is an advanced method to control the construction environment and limit embodied carbon emissions. Segments or units of the buildings will be constructed and mass-produced in an enclosed environment like a factory. They’re then transported and assembled on site. Construction in an enclosed environment allows for better management of off-site uncertainties like weather, wastage, and time delays, all of which are key factors in embodied carbon reduction. On the other hand, a lack of well-defined construction standards for modular buildings, amongst other things, limits the broad use of this construction method.
📖 The ‘Application of Modular construction in high-rise building’ research paper by Lawson, R.M mentioned that modular construction can reduce landfill waste by at least 70%, delivery vehicle visits by up to 70%, noise and disruption by 30–50%, and reportable accidents by over 80% relative to site-intensive construction.
Solution testing: What a future without embodied carbon looks like?
Unsurprisingly, 97% of the current buildings are not compliant with future carbon reduction targets. This means there’s a long way to go before the ‘Net-Zero’ deadline in 2050.
It’s evident that with current progress, we’re years away from achieving net-zero buildings, let alone carbon-positive buildings. But that shouldn’t stop us from imagining a future where embodied carbon will be eliminated from our structures. Human ingenuity will eventually solve these problems!
The completion of life-cycle assessments will allow all buildings in the world to be designed and built to clear and quantifiable net-zero targets. Hence, better controls over construction conditions will lead to better control over the carbon emission process. The technology candidates could be modular buildings or AI-controlled machines.
Not only controlled assessment and construction but operational carbon could also be reined throughout the building life cycle. Intelligent buildings with self-sensing, self-maintenance, and self-diagnosis to prevent damage and optimize energy usage during operations. These intelligent buildings will also form the building blocks of future smart cities.
CalcTree is proud to help bring that vision alive as one of the companies aiming to reduce construction and time wasted on the built environment. CalcTree will help integrate tools like LCA and Passivhaus standards in engineers’ design processes. Reducing friction in the application of new and cutting-edge approaches and materials. Join our waitlist today and become one of the first people to experience the new steps toward reducing time and material waste.
-  World Green Building Council. (September 2019). "Bringing Embodied Carbon Upfront".
-  Ravikumar, D. Zhang, D. Keoleian, G. et al. @Carbon dioxide utilization in concrete curing or mixing might not produce a net climate benefit. Nat Commun 12, 855" (2021). https://doi.org/10.1038/s41467-021-21148-w