Did you know that embodied carbon is emitted before a building is in service, and can be considerably higher than operational carbon?
Embodied carbon is the sum of greenhouse gas emissions associated with materials and resulting from a building’s construction process throughout its life cycle.
This can be estimated by carrying out a comprehensive building life cycle analysis (LCA), which is a systematic approach used to determine and quantify the environmental impacts of a product over its entire life cycle. This assessment considers factors such as energy consumption, use of non-renewable resources, GHG emissions, water consumption and waste production. The life cycle analysis of a product, building or infrastructure not only quantifies GHG emissions, but also provides information on other environmental impacts such as ozone depletion, soil and water acidification, eutrophication, smog production and non-renewable energy consumption.
A building life cycle analysis therefore includes the assessment of embodied carbon and operational carbon, which refers to energy consumption when the building is in operation.
Why talk about embodied carbon?
Climate crisis: Embodied carbon contributes significantly to the carbon footprint of buildings, intensifying the current climate crisis and calling for immediate action to reduce emissions.
Regulations and certifications: More and more environmental regulations and certifications are taking embodied carbon into account, encouraging industry players to adopt more environmentally friendly construction practices.
Innovation and research: Embodied carbon management encourages innovation in building materials, technologies and construction methods, stimulating research to design greener solutions.
Opportunity to act: Measures established in the design phase, such as choice of materials, project characteristics, targeted technologies, manufacturing processes, etc., have a major influence on carbon intensity. These decisions can affect up to 80% of a project’s environmental and social impact.
Governments want to encourage businesses to be more responsible. On May 10, 2023, Toronto became the first North American jurisdiction to require low-carbon building materials, limiting the initial intensity of embodied emissions resulting from the construction of new municipal buildings - emissions associated with the manufacture, transportation and construction of large structural and envelope systems - to less than 350 kg CO2e/m2. In addition, the Vancouver Climate Emergency Action Plan aims to reduce embodied carbon by 40% by 2030. Furthermore, Edmonton now requires an LCA for the construction of municipal buildings.
With the Greening Government Strategy, the Government of Canada has committed, through a new standard effective December 31, 2022, to reducing the environmental impact of structural building materials by disclosing the amount of embodied carbon generated by major federal construction projects. The application of this standard is based on different thresholds and aims to reduce structural emissions by 30% by 2025.1
How can an LCA help target the best reduction measures?
LCA results are used to target reduction strategies specific to a project’s characteristics. Based on the ISO 14040 and 14044 standardized processes, the results enable the sustainable development team to identify the construction materials with the highest emissions, and to evaluate alternative scenarios.
The results also enable GHG emissions to be quantified by life cycle phase: from the production of materials (A1-A3) to the construction of the building (A4-A5), its use (B1-B7) and end of life (C1-C4), while considering the benefits beyond the life cycle (D).
Reduction strategy in the design of building structures
As a consulting engineering firm, CIMA+ is in a key position to positively influence the reduction of GHG emissions from the construction sector across Canada, thanks to its involvement at several levels of project progression. Reduction strategies can be organized into four broad categories:
- Renovate existing buildings
- Rethink design
- Reduce the quantity of materials
- Reuse materials
- Change material type
- Require materials with a smaller footprint
- Reduce sourcing distance
Some examples of measures to reduce embodied carbon:
- Include in specifications a requirement to use concrete containing Portland cement substitutes such as silica fume, blast furnace slag, fly ash, glass powder and Portland limestone cement.
- Reuse existing structures in buildings.
- Choose environmentally friendly materials such as wood from sustainable sources, recycled materials or low-carbon concrete.
- Promote the use of materials with Environmental Product Declarations containing detailed information on life cycle impacts, making it easier to compare different product alternatives.
- Optimize the design of building arrangements and structure to reduce the quantity of materials required for construction.
Conducting a building life cycle analysis can involve a number of significant challenges.
Data on materials: It can be difficult to obtain comprehensive and accurate data on materials that consider emissions over their entire life cycle. The absence of certain data can make analysis incomplete or less accurate. That is why using materials with Environmental Product Declarations ensures data transparency.
Material inventory: The challenge lies in the fact that the inventory covers a wide range of materials distributed throughout the different structural systems of a building. The use of a Revit 3D model facilitates the inventory survey by providing a complete visual representation of the building, enabling the materials used to be identified more accurately and methodically.
Uncertainties: As with any analysis based on models and data, there will always be some margin of uncertainty in the results. It is important to manage these uncertainties and properly communicate the limitations of the analysis.
Stakeholder awareness and commitment: Convincing all stakeholders of the importance of life cycle analysis and actively involving them in the process can be a challenge, especially if it entails additional upfront costs or changes to usual construction practices.
LCA software: There are various software packages available for carrying out life cycle analyses, but the results vary widely, since they do not use the same databases or method for quantifying materials. It can be difficult to compare LCAs performed using these various software packages.
LCA at CIMA+
Mindful of the environmental footprint of its designs, CIMA+ has set up an embodied carbon task force to undertake initiatives to reduce the embodied carbon of certain materials used in large quantities.
Life cycle analyses at CIMA+ are carried out in close collaboration with our sustainable development team and our design team to achieve the greatest possible reduction in embodied carbon, without increasing construction costs.
Join us in this endeavour to reduce embodied carbon, and together we can revolutionize the way buildings are constructed while fighting climate change.
CIMA+ can support you every step of the way, starting with quantifying embodied carbon - because it is hard to reduce what you cannot measure!