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 embodied carbon ‘bill’ for new buildings. The ‘carbon emission bill’ starts counting from the manufacture of building materials to construction, it even keeps counting 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 [1]

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 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?

Carbon Emission from building life-cycle (Archdaily)

Let’s breakdown 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 [1].
  • 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 utilisation for concrete production (CCU concrete) will reach 0.1 to 1.4 gigatons of carbon dioxide (CO2) by 2050  [1].
  • 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 actually achieve net-zero carbon levels, or even absorb carbon in the environment, giving the asset a negative carbon footprint for it’s 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?

Carbon emission and engineers’ impact

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!

Hempcrete is an environmental friendly material, potential for sustainable construction
Hempcrete in building (Source)

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. 

A site can be surveyed using drones scanning the area. Engineers will be able to surveyed the construction site more effectively and limit the construction waste
Drone in surveying (Wingtra)

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, optimising those structures to have them lighter, slender and simpler is a prominent option to decrease the carbon emission in construction and save the operational energy. One example of such a structure is the slim floor slab structures like Deltabeam.

Deltabeam are design as lightweight structures, minimise the materials used to decrease embodied carbon
Deltabeam are lightweight column and ceiling structures (Archello)

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 from 2025 [1].

Reducing waste during construction (Rethinking The Future)

Achieve negative net carbon emission: This is called a ‘Carbon Drawdown building’, which is  able to 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.

Carbon drawdown building are buildings absorbing carbon instead of emitting carbon like most buildings nowadays
Carbon drawdown buildings (Michael, Green Architecture)

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: 

Embodied carbon in building doors (Carbon Leadership Forum

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 emission 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 optimise 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 the ideal, however it’s worth noting that formalising LCA numbers has been a hard task for a long time due to bureaucracy from international standards and legislative bodies. 

The advancement of modelling techniques such as BIM, 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. 

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
Environmental product declarations (Carbon Leadership Forum)

Otherwise, many softwares, 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:

Embodied carbon emission in different types of buildings. The best is Carbon Drawdown building!
Embodied carbon emission in different types of buildings (Carbon Leadership Forum)

Let’s look at the model of a 2000m2 building with 4 storeys and 8 units. Increasing usage of timber materials has the potential to greatly reduce the carbon content. In some cases even resulting 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.

The proposed skyscraper C6 at Perth, Australia will be the highest hybrid timber building in the word at 350 m
The proposed skyscraper C6 at Perth, Australia will be the highest hybrid timber building in the word at 350 m (Fraser and Partners, ArchitectureAU)

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 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.
Modular Construction (Panel Built)
📖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?

Green future

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 in throughout the building life cycle. Intelligent buildings with self-sensing, self-maintenance, and self-diagnosis to prevent damage and optimise energy usage during the 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 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 towards reducing time and material waste.

References

[1] World Green Building Council. (September, 2019). Bringing Embodied Carbon Upfront

[2] 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

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Published:
May 12, 2022
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May 12, 2022