Rethinking Embodied Carbon: Why ‘Upfront Carbon’ Matters for Sustainable Buildings
Changing our terminology from 'embodied carbon' to 'upfront carbon emissions' shifts the climate conversation and highlights urgent actions for building sustainability.
Rethinking Embodied Carbon: Why ‘Upfront Carbon’ Matters
As global efforts to combat climate change accelerate, the terminology we use in sustainability discourses becomes increasingly significant. In the realm of architecture, engineering, and construction (AEC), embodied carbon has emerged as a critical measure of the greenhouse gas emissions associated with making buildings. However, leading experts argue that renaming this metric upfront carbon emissions more accurately represents both the urgency and timing of its environmental impacts. This article explores the rationale behind the proposed shift in language, the technical definitions, and the implications for future building practices.
Understanding Carbon in Buildings: Two Key Concepts
When discussing the carbon footprint of buildings, two primary sources of emissions are involved:
- Operational Carbon — The greenhouse gases emitted during the ongoing use of a building, such as for heating, cooling, lighting, and powering appliances, over the building’s lifetime.
- Embodied Carbon — The emissions released during the extraction, manufacturing, transportation, installation, maintenance, and disposal of all building materials—essentially, before the building is occupied and throughout its lifecycle.
Operational Carbon Explained
Operational carbon covers all emissions stemming from energy consumed by a building, including:
- Lighting
- Heating and air conditioning
- Ventilation
- General electric power use
These emissions accrue gradually over a building’s life, which often spans 50 years or more.
Embodied Carbon (Upfront Carbon) Defined
Embodied carbon typically refers to the sum of greenhouse gases produced during the material sourcing, production, transportation, and assembly phases—effectively ‘upfront’ emissions—and continues to accumulate through maintenance, renovation, and demolition activities. Some sources now advocate replacing the term ’embodied carbon’ with ‘upfront carbon emissions’ to clarify that these emissions occur before the building is used and are ‘locked in’ at completion.
Why Does Upfront Carbon Matter So Much?
Upfront carbon emissions are released before a building is ever occupied, which means they immediately contribute to atmospheric greenhouse gas concentrations. According to the World Green Building Council, upfront carbon will account for up to half the total carbon footprint of new buildings constructed between now and 2050. In regions like Canada, Sweden, and Norway, where operational energy has shifted toward renewables, the embodied (upfront) carbon share reaches nearly 50%.
- Immediate Climate Impact: Unlike operational carbon, which accrues gradually, upfront carbon emissions impact the climate immediately upon release.
- Carbon Budget Urgency: These emissions consume a significant portion of our remaining global carbon budget, threatening climate goals unless dramatically curtailed.
- Difficulty in Mitigating: Once released, these emissions cannot be offset retroactively; mitigation must happen before construction or through material choices.
Lifecycle Stages of Carbon Emissions in Buildings
| Lifecycle Stage | Description | Carbon Type |
|---|---|---|
| Raw Material Extraction | Mining, harvesting, or extracting building materials | Embodied (Upfront) |
| Material Production | Processing raw materials into products (e.g., concrete, steel) | Embodied (Upfront) |
| Transportation | Moving materials to the construction site | Embodied (Upfront) |
| Construction/Assembly | Energy and emissions from building processes | Embodied (Upfront) |
| Renovation/Maintenance | Emissions from repairs, upgrades, and replacements | Embodied (Use-Stage) |
| Operational Use | Heating, cooling, power over the building’s lifespan | Operational |
| End-of-Life/Deconstruction | Demolition and disposal or recycling of materials | Embodied (End-of-Life) |
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Embodied Carbon vs. Upfront Carbon: Why the Debate?
The term embodied carbon has been widely used in AEC and environmental circles for years, referring to all non-operational emissions over a building’s life. However, critics argue that ‘embodied’ carbon sounds abstract, passive, or even philosophical, lacking the urgency required to spark climate action. By contrast, ‘upfront carbon emissions’ emphasizes:
- Temporal Urgency — Carbon that is immediately released and impactful
- Tangible Measurement — Focuses on quantifiable emissions during initial construction stages
- Clarity for Policymakers — Aligns with net-zero and carbon budgeting frameworks
Current Approaches: How the Building Sector Tackles Carbon
Focus Shifts in Sustainable Construction
- Historic Emphasis: For decades, the industry has focused on reducing operational carbon through energy-efficient design—insulation, efficient HVAC systems, LED lighting, and renewable energy adoption.
- Emerging Strategies: Due to the declining share of operational carbon (owing to better efficiency and cleaner energy grids), architects and engineers now target materials and construction practices—where most upfront carbon is locked in.
Measuring and Reporting Carbon: Key Metrics
The global warming potential (GWP) of building emissions is typically expressed in kilograms of carbon dioxide equivalent (kgCO2e), capturing the effects of multiple greenhouse gases relative to CO2. Methods for measuring building lifecycle carbon emissions often include:
- Material Inventories
- Process and Transportation Emissions
- Demolition and End-of-Life Assessments
- Operational Energy Calculations
Case for Renaming: Why ‘Upfront Carbon Emissions’ Drives Better Action
Proponents of shifting terminology from embodied carbon to “upfront carbon emissions” argue:
- Behavioral Change: Clear, urgent language compels immediate action among designers, builders, and policy makers.
- Policy Leverage: Upfront emissions can be regulated through building codes, procurement policies, and design standards—affecting projects before they begin.
- Accounting Rigor: Identifying which carbon can be prevented before occupancy clarifies where mitigation is possible.
- Budget Alignment: Upfront carbon aligns with net-zero targets and carbon budgeting by drawing attention to emissions that cannot be offset later.
Common Myths and Misunderstandings
- Myth: Operational carbon always dominates carbon footprints.
Reality: As energy grids decarbonize, operational carbon shrinks relative to the upfront share, especially in new construction. - Myth: Upfront carbon can be offset through later energy savings.
Reality: Once released, upfront carbon emissions are permanent and cannot be reversed by future operational efficiency. - Myth: All embodied emissions occur before occupancy.
Reality: Some embodied emissions arise during use (through maintenance and renovations) and at the end of life (demolition/recycling).
Strategies for Reducing Upfront Carbon Emissions
- Material Choices: Prioritize low-carbon materials such as engineered timber, recycled steel, and low-emission concrete.
- Design Efficiency: Streamline structures to use fewer materials without compromising safety or longevity.
- Local Sourcing: Minimize transportation emissions by sourcing materials closer to the construction site.
- Innovative Methods: Employ prefabrication and modular building techniques to reduce waste and construction impacts.
- Lifecycle Assessment: Adopt tools and certifications (LEED, BREEAM, LCA Platforms) for transparent reporting and benchmarking.
Table: Embodied vs. Upfront Carbon Comparison
| Term | Definition | Impacts Addressed | Timeframe of Emissions |
|---|---|---|---|
| Embodied Carbon | All non-operational lifecycle emissions (materials, construction, maintenance, demolition) | Material extraction, production, transport, installation, maintenance, demolition | Before, during, and after building use |
| Upfront Carbon Emissions | Emissions released before building occupancy, mainly during material production, transport, and construction | Early-stage materials and construction activities | Immediately before building use |
Where Does the Debate Leave Us?
The language shift from embodied carbon to upfront carbon emissions is more than semantics. It represents a strategic prioritization in climate action for the building sector. By zeroing in on emissions that are released—and locked in—before a building is occupied, professionals and policymakers can set standards and benchmarks that make a measurable, urgent difference for the climate.
Frequently Asked Questions (FAQs)
Q: What exactly is embodied carbon in a building?
A: Embodied carbon refers to all greenhouse gas emissions associated with the building material lifecycle, including sourcing, production, transport, construction, repair, and demolition.
Q: Why ‘upfront carbon emissions’ instead of ‘embodied carbon’?
A: ‘Upfront carbon emissions’ highlights the timing and urgency of emissions released prior to occupancy, making it clear that these cannot be offset later and are crucial for immediate climate action.
Q: Can we offset upfront carbon with future renewable energy savings?
A: No. Upfront carbon emissions are released before the building is used and cannot be recovered; future operational efficiency cannot reverse their impacts.
Q: Is embodied carbon relevant after building completion?
A: Yes. Embodied carbon also includes emissions from maintenance, renovations, and end-of-life demolition, but upfront carbon forms the largest, immediate share in new construction.
Key Takeaways
- Changing terminology from ’embodied carbon’ to ‘upfront carbon emissions’ can drive faster climate action in the building sector.
- Upfront carbon is a critical measure because it is locked in before occupancy and cannot be offset retroactively.
- As operational emissions decline, upfront carbon now comprises nearly half of the total footprint in advanced economies.
- Materials, design, sourcing, and construction phase decisions offer the greatest leverage to reduce immediate climate impacts from new buildings.
References to Authorities and Standard-Setting Bodies
- World Green Building Council (WorldGBC): Frameworks for distinguishing upfront and embodied carbon.
- International Energy Agency (IEA): Reports on built environment emissions.
- Leading AEC industry researchers: Endorse language clarity for carbon policy advances.
References
- https://se2050.org/resources-overview/embodied-carbon/what-is-embodied-carbon/
- https://oneclicklca.com/en-us/resources/articles/embodied-carbon-vs-operational-carbon
- https://www.aia.org/sites/default/files/2024-11/AIA_CLF_EmbodiedCarbonToolkit_Part1.pdf
- https://nordesg.de/en/the-confusion-about-embodied-carbon-and-scope-emissions-nordesg/
- https://www.gresb.com/nl-en/what-is-embodied-carbon-in-the-real-estate-sector-and-why-does-it-matter/
- https://ukgbc.org/wp-content/uploads/2023/02/operational-and-embodied-carbon-1.pdf
- https://savingplaces.org/stories/upfront-carbon-and-why-it-matters
- https://imegcorp.com/insights/blog/know-the-difference-between-operational-and-embodied-carbon/
- https://www.iesve.com/discoveries/view/45462/embodied-carbon-vs-operational-carbon
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