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Section 2: Early carbon optimization

How can you optimize carbon early?

Once you realize the significance of optimizing embodied carbon early during the project, it is important to know how to do it.  This section summarises the information required for early carbon optimization and how it can be achieved.

What information is required when assessing embodied carbon at an early stage?

Information required Description  How to obtain this information
Material Quantities Material quantities at the earliest stages and more detailed material quantities as the design evolves (Volume, area, length, pieces, KW, etc.) Import details from models (e.g., Rhinoceros 3D), and cost plans (optional), add them manually, or use Carbon designer 3 D
Material Specification Concrete strength, percentage fly ash, reinforcement details  Requires multiple parties to be involved in this, but information on structural materials is obtained mainly from structural engineers; other building parts are specified on an element type basis (example type of facade)
Impact Data of specified material  kg CO2 of the product EPDs, generic and manufacturer-specific data, One Click LCA database 
Lifespan of materials and products When the materials/ products should be replaced One Click LCA gives this information (otherwise, you have to search for the information)
Transportation distances Transportation from the manufacturer’s site to the construction site One Click LCA provides default values for transport distances, which can be used when the specific source is not known 
The typical workflow for early embodied carbon and LCA optimization

  1. Find out the type of building, life cycle, and geometry.
  2. Collect material information.
  3. Import details from models (eg Rhinoceros), and cost plans or add them manually.
  4. Perform hot spot analysis and identify improvement opportunities.
  5. Create and assess additional options to measure improvement.
  6. Report back to the client and design team to incorporate improvements into the design.
Early-phase assessments provide the highest potential to influence carbon. The steps to carry out an early phase assessment are described in detail below:

Have a preliminary Bill of Materials (BoM): Due to the nature of embodied carbon and the requirements for its calculation, approaching embodied carbon early on will require a preliminary Bill of Materials. This includes the material, its quantity in units, and material class (see Fig 4.)

Fig 4. Sample Bill of Materials used in early carbon optimization

Obtain a carbon overview of the to-be project: Since the bill of materials is known, utilizing specialized software – such as One Click LCA – will inform you of the Embodied Carbon results of your project. Visualizations like the one shown (Fig 5), allow users to quickly identify carbon hotspots and focus on resolving the issues.

Fig 5. Visualization of hotspots in the early design stage using One Click LCA Carbon designer

Influence material choices and optioneering: Prioritise materials that are low or zero carbon, responsibly sourced, and which have low lifecycle impact in other areas, including the health of the occupant, as determined through a product-specific environmental product declaration where available. As a thumb rule, heavily thermally processed materials have higher embodied carbon potential (see Fig 6)

Fig. 6: The carbon footprint of construction materials
Fig 6. shows commonly used mineral-based construction materials (varying from least processed to heavily thermal processed), some examples being,

  • Low processing end: rammed earth, crushed concrete, natural stone, sun-dried bricks.
  • Heavily thermal processed: cement, glass slaked lime.
  • Heavier the thermal processing required, larger will be the carbon footprint of the materials (refer to the materials section for further details).
  • Optioneer without pre-existing material constraints.

Perform cost vs carbon analyses: perform cost and carbon comparisons to make the right and most efficient choices. Since cost is always treated with the highest priority, it is important to be able to assess designs with respect to both cost and carbon emissions (see Fig 7). The most optimal solution for a material selection would mostly be a compromise between cost and low enough carbon emissions.

Fig 7. Sample cost vs. carbon assessments

Examine shape and size against Embodied Carbon: Identify how shape (and size) can affect your project’s embodied carbon performance. This can be done by iteratively optimizing your design.

You can combine LCA and parametric tools to explore multiple different options and choose the most appropriate one based on the chosen set of criteria. For instance, by combining One Click LCA’s Grasshopper Plugin and Octopus, a user will be able to iteratively explore design alternatives by providing a set of parameters that include, but are not limited to:

  • Building dimensions
  • Possible materials for each building geometry
  • Cost
  • Structural properties

Even though these algorithms will not provide a definitive solution after they are left to run for multiple generations, they typically converge to a single range of possible solutions. Additionally, it is possible to create constraints using Grasshopper’s components that would regulate the maximum and minimum range of possible solutions.

Fig 8. Iteratively optimizing your design using parametric tools

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Understanding the construction materials

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Early carbon optimization

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