For many years now, the construction industry has focused its climate efforts on reducing the operational emissions from lighting, heating, cooling, hot water, and other plug loads. As a result, it made great strides in increasing efficiencies and adopting renewable energy sources. However, there is another source of emissions associated with buildings that is critical we address today: embodied carbon.
What is Embodied Carbon?
Embodied carbon is distinct from operational carbon as it refers to the carbon dioxide (CO₂) emissions associated with materials, manufacturing, and construction processes throughout the whole lifecycle of a product, building, or infrastructure.
Embodied carbon encompasses any CO₂ emitted:
- During the manufacturing of building materials (material extraction, transport to manufacturer, manufacturing)
- When transporting the materials to the job site
- By the construction practices used
- When maintaining the building
- When eventually demolishing the building, transporting the waste, and recycling it
Some embodied carbon is already in the atmosphere by the time building materials reach the project site. That’s why it’s crucial the construction industry focuses on embodied carbon today.
Tackling Embodied Carbon in Construction
Advances in reducing operational carbon have placed the spotlight on embodied carbon in recent years. Research by the World Green Building Council indicates that embodied carbon is a larger portion of a building's overall carbon footprint than previously thought.
To address this, initiatives and organizations like Architecture 2030, Structural Engineers 2050 Challenge, the Carbon Leadership Forum, and the World Green Building Council have jointly taken on a mission to eliminate embodied carbon from buildings by the year 2050.
Why Now, and Why Concrete?
This decade is our last chance to address climate change—the world must halve its carbon emissions by 2030 to meet the goals of the Paris Agreement.
Buildings contribute around 40% of emissions worldwide. With the world’s building stock expected to double by 2060—that's equivalent to adding an entire New York City to the planet every month for the next 40 years—it is critical that the construction community understands its role in reducing the sector’s carbon footprint and how to use the tools available to assist them.
The expected boom in construction is good news for concrete producers. However, cement—the key ingredient that gives concrete its strength—is also one of the largest emitters of CO2 in the built environment.
Since concrete is the most abundant human-made material in the world, cement production creates ~7% of the world’s annual CO2 emissions—and is therefore one of the largest contributors to embodied carbon in the built environment.
Calculating Embodied Carbon
The Carbon Leadership Forum collaborated with Skanska, C Change Labs, and Microsoft to launch a special tool for calculating the embodied carbon of building materials: the Embodied Carbon in Construction Calculator (EC3).
The tool provides developers and designers with information about the embodied carbon impact of building materials during the material selection process and inherently provides an advantage to lower carbon products.
For concrete producers, the development of EC3 is significant as it represents a new way to gain a competitive advantage. Concrete producers that publish product-specific EPDs for low carbon concrete will automatically appear in searches within the EC3 tool for consideration by specifiers.
The EC3 tool utilizes building material data from construction estimates and building information modeling (BIM) as well as a robust database of digital, third-party verified Environmental Product Declarations (EPDs).
EC3 does not replace the whole building life cycle assessment (WBLCA). Instead, it fills the gap between early design assessments at the systems level using available WBLCA tools and the actual procurement of low carbon products.
Tackling Embodied Carbon
There are several ways to reduce the embodied carbon of construction including:
1. Specify low carbon concrete mixes
One of the simplest ways to move the needle on embodied carbon is to change the way concrete is specified. The weight and prevalence of concrete make it typically the biggest source of embodied carbon in any project. Structural engineers can specify lower carbon concrete mixes by using fly ash, slag, calcined clays, or by allowing producers to use carbon mineralization technology like CarbonCure.
2. Recycle and reuse materials
Whenever possible, salvage materials like brick, metals, broken concrete, or water.
Recycled materials typically have a much lower embodied carbon footprint than virgin materials, since the carbon to manufacture them has already been spent.
With reclaimed water from concrete truck washouts, you not only save the energy that would have been spent manufacturing and transporting virgin cement to the plant, but the water can also be reused to reduce waste.
3. Reduce the use of finishing materials
It is very popular to use structural materials as finishes these days. They not only look good, they save significant embodied carbon. For example, polished concrete slabs as finished flooring saves the embodied carbon from carpet or vinyl flooring.
How is Embodied Carbon Used in Decision-Making?
Embodied Carbon is often used to compare the environmental impacts of different building materials, designs, and construction processes. Comparing embodied carbon calculations can help identify carbon-intensive elements and promote alternative low carbon options.
Because of the increased focus on embodied carbon, building materials manufacturers—especially concrete producers—have a huge competitive advantage if they can meet the growing demand for low carbon materials.
Whether you’re a member of the AEC community looking to reduce the environmental footprint of your project or a concrete producer looking for new opportunities in the green building space, CarbonCure is a great way to start the conversation about embodied carbon.