Guide to reducing embodied carbon
key actions to reduce embodied carbon throughout the building's life cycle
It is necessary to adopt a “Whole life carbon” approach that considers both embodied and operational carbon throughout the entire life cycle of buildings.
The construction, use and demolition processes of buildings are responsible for around 39% of global Greenhouse Gas (GHG) emissions responsible for the global warming.
This 39% is made up of 28% emissions due to the energy consumed during the use phase of the building (operational carbon) and 11% from GHG emissions during the extraction, manufacturing, installation, maintenance and demolition of the buildings. materials that make up the building (embodied carbon).
Today’s buildings are becoming more efficient and use more renewable energy generated on site or from the grid. We can assume that these trends will continue in the future, which will imply a reduction in the relative weight of operational carbon emissions.
source: Vca-arch
However, from the moment the construction of a building is completed and before it is occupied and used, tons of CO2e have already been emitted into the atmosphere during the extraction, manufacturing, transportation and installation of the materials that make up the building.
Regardless of the energy control measures that we have implemented, such as insulation, solar control, efficient air conditioning equipment, photovoltaic panels, etc., that portion of CO2 is already contributing to the greenhouse effect in the atmosphere and therefore increasing the global warming.
As we can see in the diagram made by Architecture 2030, in 2030 embodied emissions will account for 74% of the total emissions coming from the construction sector, and by 2050, embodied emissions will represent almost half of the total climate impact generated by buildings. new buildings we are designing today. Therefore, its reduction is essential to meet the decarbonization objectives necessary to limit global warming.
What actions can we implement during the planning, design and construction phases to reduce the embodied carbon of buildings?
1 – Planning or pre-design phase
- Consider emissions reduction from the initial design phases including site selection:
Build in already urbanized places and avoid the construction of new infrastructure that will generate more GHG emissions.
Avoid urbanizing natural areas by losing vegetation that can absorb CO2.
Always consider the option of rehabilitating and reusing existing buildings.
Identify in-situ materials with the potential to be reused in new construction.
- Include strategies to reduce the amount of material used in construction:
Reduce the footprint of the building by optimizing the program and considering multiple uses for the spaces.
Design flexible buildings that can be reused in the future with minor changes. (Open spaces, dry and movable partitions,etc).
Design compact and efficient structures by reducing redundant elements.
2 – Design
- Perform Life Cycle Analysis iteratively throughout the design.
Carry out an initial life cycle assessment in the pre-project phase to determine the embodied carbon baseline of the project.
Use LCA to identify “critical points”; materials or systems with highest carbon intensities.
Establish a carbon reduction goal for the project, according science based decarbonization targets.
Use LCA to test material alternatives, focusing on foundation, structure, and enclosure materials.
- Select construction systems that minimize embodied carbon:
Specify prefabricated construction systems that reduce material waste and construction time.
Evaluate the use of structural systems based on materials with the capacity to sequester carbon during their growth, such as wood.
Minimize the use of interior finishing materials, for example by eliminating false ceilings, leaving the facilities and structures visible.
Design for deconstruction and reuse to minimize waste generated at the end of the building’s life by promoting the circular economy.
- Specify materials with low embodied carbon:
Rescued or recovered materials.
Use locally manufactured materials.
Use materials made with renewable energy.
Materials with high recycled content.
Use biobased materials that sequester C02 during their growth such as wood, bamboo, cork, hemp, etc.
Use materials with very high durability.
Prioritize materials with Environmental Product Declaration.
3 – Construction
- Reduce emissions due to the construction phase:
Use digitalization tools such as BIM to calculate and supply materials accurately and avoid waste on site.
Apply Lean planning strategies.
Use electric or biofuel-based machinery.
Perform Life Cycle Analysis to evaluate design or material variations made during the construction phase.
Carry out effective waste management that prioritizes waste recovery over sending it to landfill.
4 – Post construction
- Compensate for excess embodied carbon.
Carry out a final life cycle evaluation with the ‘as built’ information.
Compare the results with the emissions limits established in the design phase.
Offset emissions that exceed the limits established by the decarbonization route through certified carbon sequestration programs.
