Embodied Carbon
The greenhouse gas emissions locked into a building by its materials and construction.
Quick Answer
Embodied carbon is the greenhouse gas emissions associated with a building's materials and construction: extracting raw materials, manufacturing products, transporting them, installing them, and eventually maintaining and disposing of them. It is expressed as CO2-equivalent, and most of it is emitted before the building opens, so early material decisions have the largest effect.
The Full Picture
Embodied carbon exists as a distinct concept because buildings emit greenhouse gases long before anyone turns on the lights. Making cement, smelting steel, and producing glass and insulation all release emissions, and those emissions are already in the atmosphere on the day of occupancy. As operating energy gets cleaner, embodied carbon becomes a larger share of a building's total climate impact.
Practitioners measure it as global warming potential (GWP), reported in kilograms or tonnes of CO2-equivalent. The standard framing is the set of life-cycle modules defined in EN 15978 and ISO 21930-style product rules. Modules A1 to A3 cover product manufacturing, A4 to A5 cover transport and construction, B covers use-phase maintenance and replacement, and C covers demolition and disposal. The A1 to A5 total is often called upfront carbon.
In practice, a few materials dominate. Concrete, structural steel, and reinforcing steel usually account for most of a typical building's upfront carbon, with envelope and finishes contributing less. A calculation multiplies material quantities by emission factors, ideally taken from product-specific Environmental Product Declarations rather than generic averages. Free tools such as EC3 from Building Transparency exist for this purpose.
For a general contractor, embodied carbon is a precon issue because the levers are pulled before the pour. Mix design, supplementary cementitious material content, steel sourcing, and substitution of materials all get decided during design development, estimating, and buyout. Owners increasingly write carbon limits or reporting requirements into RFPs and contracts, so the preconstruction team ends up pricing and procuring against a carbon target as well as a budget.
Real Examples
Common Misconceptions
People assume: Embodied carbon is just a small add-on to a building's energy use.
Actually: In modern, efficient buildings embodied carbon can rival or exceed operational emissions over the first decades of life, and almost all upfront carbon is emitted before occupancy, when it cannot be recovered later.
People assume: Embodied carbon only matters for new construction.
Actually: Renovation, reuse, and material choices in tenant improvements all have embodied carbon. Reusing an existing structure usually avoids most of the emissions a new frame would add.
People assume: Using one low-carbon material makes a building low-carbon.
Actually: Total embodied carbon depends on quantities of every major material, so a lower-carbon product can be offset by using more of it or by heavier structural systems elsewhere.
Frequently Asked Questions
What is embodied carbon in simple terms?
It is the carbon dioxide and other greenhouse gases released to produce and assemble a building's materials, expressed as CO2-equivalent. It includes extraction, manufacturing, transport, installation, and, in broader accounting, maintenance and end of life. It is separate from the emissions created by heating, cooling, and powering the building.
What is the difference between embodied and operational carbon?
Embodied carbon comes from materials and construction and is largely emitted before occupancy. Operational carbon comes from energy used while the building operates. Reducing operational carbon is an ongoing process, while embodied carbon is mostly locked in once construction is complete.
Which materials contribute the most embodied carbon?
In most commercial buildings, concrete and steel dominate, followed by envelope components such as glazing and insulation. The exact mix depends on the structural system, so a project-specific calculation is more reliable than a rule of thumb.
How is embodied carbon measured?
Material quantities from a takeoff or model are multiplied by emission factors, preferably from verified EPDs, and summed in CO2-equivalent. Results are often normalized per square foot or square meter to compare designs.
Why does embodied carbon matter for preconstruction?
Material selection, mix design, and procurement decisions happen during precon, and they determine most of the upfront carbon. Reductions are cheapest to make before orders are placed.