Most conversations about the carbon footprint of a building focus on the activities that go on inside the completed construction. The HVAC system and lighting, for example, contribute to the building’s operational carbon footprint. But there is an additional type of carbon emissions to consider: embodied carbon, which can account for as much as half its lifetime environmental impact.
Like every manufactured product, a building comes with a large serving of embodied carbon, the carbon dioxide emissions associated with the materials and construction processes of a building or infrastructure throughout its full life cycle. This includes raw material extraction, manufacturing, transportation, installation, maintenance, renovation, and disposal of building materials. It is the carbon footprint of a building before it becomes operational. Steel, concrete, and insulation are some of the materials that contribute to these emissions.
The impact of embodied carbon is typically expressed in carbon dioxide equivalent units (CO2e), which represents the future global warming potential (GWP) of the emissions over their lifetime. Carbon dioxide decays by half every 120 years, so it will take about 1,200 years for all of a building’s embodied carbon to be removed from the atmosphere if it is not captured and sequestered in the ground or a growing forest.
Because of the current lack of visibility into where materials are sourced, manufactured, and how they are shipped, embodied is more difficult to measure and track than operational carbon. It is often only shared as a result of manufacturers self-reporting data.
Why Is Embodied Carbon Important?
Because these emissions are so difficult to measure, they have received little attention until recently. According to the World Green Building Council, the embodied carbon in materials and construction of buildings alone accounts for 11% of global carbon emissions. This will grow as a percentage as the operational footprint of buildings decreases due to improved heating and cooling technology and other factors.
Embodied carbon is expected to account for nearly half of the overall carbon footprint of new construction between now and 2050. With the building sector responsible for about 30% of all global carbon emissions, addressing embodied carbon is a priority.
How Do We Address This Problem?
In addition to the home or building owner who make the ultimate choice about what gets built, architects, engineers, contractors, materials manufacturers, and regulators all have a role to play in reducing embodied carbon. An important step is beginning to measure carbon released in the supply chain and at a building site.
Surveyors, architects, and designers can estimate embodied carbon at the design stage of a construction project and identify ways to lower emissions. The industry needs effective tools to measure and mitigate embodied CO2. So far, only one such tool exists. A nonprofit consortium in the construction industry developed the Embodied Carbon in Construction Calculator (EC3). This free, cloud-based, open-source tool utilizes data to encourage better materials choices and address embodied CO2 throughout the construction’s life cycle. EC3 is primarily for professional business use, but individuals will be granted limited access upon request and can explore the data. Check out the user guide to learn more about this tool.
Reducing embodied carbon will take some major transformation in multiple industries related to construction. The largest sources of emissions in this sector, for example, include the production of cement, iron, and steel. Leaders from all these fields will need to collaborate to improve their products and processes in order to reduce emissions.
What Can the Construction Industry Do?
Public and private policy can influence decisions manufacturers make with regard to embodied carbon emissions. A group of organizations has joined forces to eliminate it from buildings by 2050. Several localities have set up procurement policies focused on reducing embodied CO2, including Buy Clean California; Portland, Oregon’s Low Carbon Concrete Initiative; and Hawaii’s Carbon Dioxide Mineralized Concrete. Finally, the building industry recently announced that is it seeking to reduce the carbon footprint of concrete construction. Research shows that 81% of structural engineers and 69% of contractors working with concrete are tracking the embodied CO2 on their projects. About one-third are already reducing it.
Some strategies to reduce construction-related emissions include:
- Don’t ship materials long distances to a building site.
- Choose construction products made with locally available raw materials using energy-efficient and low-emission processes.
- Transport materials with low-carbon vehicles.
- Minimize and recycle waste during the construction process.
- Choose used and recycled products when possible.
- Use products and systems that have long life spans.
- Design buildings for easy conversion to other uses over time to minimize future upgrades and renovation.
- Reduce material quantities.
Embodied carbon mitigation is a fairly new endeavor, so watch for more developments as the construction industry and other industries make progress.
Want to learn more? Watch this video from the World Green Building Council: