NEED FOR EARLY CARBON OPTIMIZATION
Optimizing carbon in various project stages
Conducting Life Cycle Assessment (LCA) helps to measure and reduce the environmental impacts of your building, achieve green building certifications, and comply with regulations. Depending on the objective, LCA can be performed during multiple stages of a project and can provide various advantages (refer to Table 1).
| Project stage |
Advantages of performing building LCA |
| Site selection stage |
- Calculate influence of the site on carbon footprint (to calculate the foundation type required, soil stabilization requirements, etc)
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| Concept stage |
- Obtain baseline (for LEED and other certification purposes, to measure reduction against baseline)
- Set embodied carbon and whole-life carbon goals/targets
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| Technical stage |
- Explore material efficiency
- Check for sustainable alternatives
- Perform structural LCA, architectural LCA, services LCA
- Achieve certification
|
| Specification stage |
- Choose materials by EPDs
- Responsible sourcing
- Material efficiency
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| Post-construction |
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Table 1. Advantages of performing LCA during various project stages
LCA can be performed at multiple stages but if your goal is to achieve maximum embodied carbon reduction, you need to perform it when you have the maximum power to influence design and specification choices.
Strategies to reduce embodied carbon
The Carbon Neutral Cities Alliance (CNCA) has identified five different tactics that can be deployed to reduce carbon emissions(see Fig 1).
- Redefine the solution: finding alternative ways to reduce carbon. For example, if a leisure time facility is underused, the problem may relate to public transport access as opposed to needing to rebuild or renovate the building.
- Refurbish existing assets: This reduces total materials use and can be a powerful decarbonisation strategy where it does not compromise energy efficiency. For example, renovations to increase usage efficiency in capacity, occupancy, or both.
- Reduce and Replace materials and structures by design and use lower carbon structures and materials where appropriate.
- Reuse products and materials, at end of life for additional uses for unused products from sites and for salvaged materials from refurbishments and demolitions
- Require low carbon products, for example specifying low carbon products while limiting and/or substituting the use of high carbon materials for lower impact ones.
Fig 1. Embodied carbon reduction potential
During the early design stages, there is greater flexibility to influence all of the steps to reduce embodied carbon. During this stage, design teams have the capability to assess different solutions, structural frames, locations, material choices, and many more.
Identifying the stage with the highest potential
Cost considerations
Fig 2. Cost vs. Carbon during project stages
Cost becomes a significant limiting factor as the project moves forward in time (see Fig. 2). For example, in the pre-construction phase, when materials have already been specified and orders have been placed, allocating an extra budget for procuring low-carbon materials is not a feasible option and will affect the sustainability outcome of the project. Even from a business perspective, incorporating LCAs as early as possible allows designers to differentiate tenders by providing an extra offering.
Design considerations — Certain design elements are better addressed early in the design process. Once these are fixed, it may result in additional costs to re-address it at a later stage. For this reason, it is recommended to integrate LCA as early as possible in the design process. For example, is more appropriate for early stages than product procurement for example looking at the structural frame, foundation, and slab options. If you change your mind later, you will need to redesign the entire thing which results in extra costs.
Certification schemes and regulations that promote early carbon optimization
| Schemes |
Description |
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GLA London Plan
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- Requires the Whole Life Carbon (WLC) Assessment to be performed in three stages including pre-application and planning submission stage.
- The Planning submission stage is the most critical stage, as it can affect whether or not planning is approved.
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Living building challenge
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- Requires that the embodied carbon emissions from the foundation, structure, and enclosure have been reduced by a minimum of 10%, compared to the baseline scenario.
- The total embodied carbon emissions of the project must not exceed 500 kg-CO₂e/m².
- If you want to meet these targets, then measuring your project’s embodied carbon at an early stage is critical.
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LEED
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- In LEED certification, credits are offered based on the percentage reduction from the baseline.
- Though there is no requirement for early carbon optimization as such, it will be tough to meet the maximum credits if you do not optimize embodied carbon during the early phase.
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Table 2.Certification schemes, and regulations that promote early design (either directly or indirectly)
TOOLS THAT HELP YOU WITH EARLY CARBON OPTIMISATION
Challenges while performing early carbon assessments
The main challenge when we want to perform an LCA at the early design stage is the lack of information, whether this is the material specifications, quantities, or even the specific material impact information.
Since the goal of an early stage LCA is to obtain a general overview of the anticipated carbon emissions, it can be acceptable to use previous projects’ information and extrapolate accordingly. However, such a methodological approach would entail dangers because it makes it difficult to assess multiple design options (i.e., the quantities required for a concrete frame are not the same when assessing timber frames, etc).
Listed below are some potential tools to help you overcome these challenges.
Create baseline
Carbon designer
Carbon designer is an early design tool that allows you to get a Bill of materials (BOM) without needing a design. It is a shoebox analysis model but useful for the early design stage.
Benefits
- Early Design Tool
- Uses local average data
- Obtain BOM without needing a design
- Minimal amount of information required
- Perform cost vs carbon analyses
Features
- Create baselines with minimum data such as GFA, country/region, building type, and number of floors
- Allows for optional choices such as underground floors, soil conditions, structural solutions etc
- Templates allow you to reuse your baselines in any number of projects quickly and easily
- Quick and easy visual comparison by rapidly making variants by changing between pre-defined building structures or relevant material choices
- As only very limited background information is needed to start, the tool can be used already in early design stages and target setting but it can also support detailed options and creation
- The modelled building can also be saved to any of our LCA calculation tools
Fig 1. Visualization of hotspots in the early design stage using One Click LCA Carbon Designer 3D
Typical workflow
- Enter basic information (size, ref building, service life)
- Select your building type
- Define the scope of the analysis (select the building parts you want to work with)
- Choose your baseline structural frame (concrete, steel, timber, etc)
- Review and calculate the final geometry
- Review and amend material quantities
- Review your first results
Carbon Designer 3D by One Click LCA allows non-experts to calculate and optimize embodied carbon in construction projects from the earliest project phases.
BIM tools
Rhino and grasshopper integrations
One Click LCA has developed integrations with Rhino and Grasshopper to help design teams implement carbon assessments from the earliest stages. The Rhino integration is designed to allow users to directly assign materials to the drawn layers and eventually get a result for their project. This allows design teams to quickly identify where the carbon hotspots might be located in the final design and tackle them from early on.
Fig 2. BIM tools for early carbon optimization
Grasshopper is a visual programming editor that works as a plug-in for the 3D modelling software Rhinoceros. You can define algorithms in Grasshopper to automate tasks in Rhino. You can for instance use Grasshopper to automatically generate a building geometry based on some fundamental parameters such as width, height or column spacing. Such geometric automatizations open up new possibilities for life-cycle assessments. Now you can use these generated 3D models to automatically extract the material quantities for your LCA.
Grasshopper’s intent is to not only allow users to understand early impacts but assist them in redefining the solution altogether. As mentioned earlier, the parametric nature of grasshopper, coupled with the fact that it allows for iterative design.
Fig 3. Iteratively optimizing your design using parametric tools
Benefits
See in real-time how changing your parameters affect your project’s embodied carbon.
Typical workflow
- Set up your initial script
- Choose the materials you want to use
- Run and LCA within grasshopper
- See in real-time how changing your parameters affect your projects embodied carbon
Combine grasshopper and carbon designer to develop full-scale buildings
Early design in GH (only column, walls), you can add this to OCL and using CD you can fill in the gaps and have a full building LCA done
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