Embodied Carbon in Construction and How to Choose Low Carbon Materials

What Is Embodied Carbon in Construction?

Embodied carbon is the greenhouse gas emissions associated with extracting, manufacturing, transporting, installing, maintaining and disposing of construction materials. It is usually measured as kilograms of carbon dioxide equivalent, or kg CO₂e, and forms part of a building's whole-life carbon footprint.

Embodied carbon may include emissions from:

• Raw-material extraction
• Product manufacturing
• Transport to site
• Construction and installation
• Maintenance and replacement
• Demolition, reuse, recycling or disposal

Embodied carbon is not contained only in the finished material. It represents lifecycle emissions associated with creating, using and managing that material.

Embodied Carbon vs Operational Carbon

Embodied Carbon

Generated through:

• Materials
• Manufacturing
• Transport
• Construction
• Maintenance
• End-of-life processes

Operational Carbon

Generated through:

• Heating and cooling
• Lighting
• Ventilation
• Building equipment
• Energy consumed during occupation

Core Takeaway

Operational emissions can often be reduced over time through renewable energy and efficiency improvements. Upfront embodied emissions have already entered the atmosphere before the building begins operating. The balance between embodied and operational emissions varies according to the building, energy source, design and expected service life.

Where Does Embodied Carbon Occur in a Building Lifecycle?

Whole-life carbon assessment examines more than upfront product emissions.

Product Stage

Raw-material supply, transport to manufacturing and manufacturing.

Examples:

• Cement and clinker production
• Steelmaking
• Timber processing
• Insulation production

Construction Stage

Transport to site and construction or installation activities.

Examples:

• Delivery distances
• Site fuel use
• Equipment operation
• Material waste
• Temporary works

Use and Maintenance Stage

Replacement, repair, refurbishment and maintenance activities continue to generate embodied impacts throughout the building's operational life.

End-of-Life Stage

Deconstruction, demolition, transport, waste processing, reuse and disposal create final embodied emissions as the building reaches end of service life.

How Is Embodied Carbon Calculated?

Step 1: Define the Assessment Boundary

Decide which lifecycle stages, building elements and project activities will be included.

Step 2: Create a Material Quantity Schedule

Record concrete, steel, timber, glass, insulation and other products by mass, volume or installed unit.

Step 3: Collect Carbon Factors

Obtain product-specific EPD data where available or use suitable industry-average datasets.

Step 4: Multiply Quantity by Carbon Factor

Embodied carbon = material quantity × emission factor

Step 5: Add Additional Impacts

Add transport, installation, maintenance and end-of-life impacts to the product-stage calculation.

Step 6: Report Assumptions, Exclusions and Data Quality

Document methodology, data sources, assumptions and any limitations in the assessment.

Standards for Calculation

Life Cycle Assessment, or LCA, provides the structured methodology used to evaluate lifecycle environmental impacts. ISO 14044 covers goal and scope definition, inventory analysis, impact assessment, interpretation, reporting and critical review. This standardised approach ensures consistency and credibility across embodied carbon assessments.

What Is an Environmental Product Declaration?

An Environmental Product Declaration, or EPD, is a structured declaration presenting lifecycle environmental information about a product according to defined rules.

An EPD can provide:

• Global Warming Potential data
• Declared or functional units
• Lifecycle-module results
• Product assumptions
• Manufacturing information
• Verification details

Important Comparison Warning

Do not compare two EPD values unless their declared units, lifecycle boundaries, product functions, service assumptions and calculation rules are sufficiently comparable. Comparing EPDs without understanding their boundaries can lead to misleading material selections.

The current ISO 14025:2026 specifies requirements and guidance for EPD programmes and associated declarations and connects their development to ISO 14040 and ISO 14044.

Building Knowledge in Environmental Performance

Professionals responsible for environmental impacts, risk controls, legal responsibilities and ESG performance can develop broader practical knowledge through the Environmental Safety & Sustainability (ESG) course. This training integrates embodied carbon assessment, whole-life carbon strategies, material selection, procurement responsibility and lifecycle thinking into a comprehensive environmental management framework.

How to Choose Low-Carbon Construction Materials

Do not select materials using carbon data alone. Compare carbon performance alongside structural requirements, durability, fire safety, worker exposure, maintenance, availability and expected service life.

Five-Step Selection Framework

1. Reduce the quantity required

Ask whether the design can achieve the required performance with:

• Less material
• Fewer finishes
• More efficient structural systems
• Standardised dimensions
• Lower construction waste

2. Compare products performing the same function

Avoid comparing materials that provide different:

• Strength
• Fire resistance
• Acoustic performance
• Thermal resistance
• Durability
• Service life

3. Request product-specific EPDs

Prefer current, relevant and independently verified information where available.

4. Assess transport and supply-chain impacts

Consider:

• Production location
• Delivery distance
• Transport mode
• Supplier energy sources
• Material traceability

5. Review safety and lifecycle performance

Confirm that the lower-carbon option remains suitable for:

• Installation
• Worker exposure
• Structural loading
• Fire performance
• Maintenance
• Future disassembly or reuse

Which Building Materials Can Reduce Embodied Carbon?

Low-Carbon Concrete

Practical options include:

• Optimised mix design
• Reduced clinker content
• Supplementary cementitious materials
• Recycled aggregate where appropriate
• Locally produced concrete
• Performance-based specifications

A lower-cement mix must still satisfy required strength, curing, exposure, durability and quality-control requirements.

Low-Carbon and Recycled Steel

Potential factors include:

• High recycled content
• Efficient structural design
• Reused steel sections
• Lower-emission production routes
• Supplier-specific EPD data
• Design for future disassembly

Recycled content alone does not provide the complete product footprint.

Timber and Bio-Based Materials

Coverage includes:

• Mass timber
• Cross-laminated timber
• Engineered timber
• Hemp-based products
• Other responsibly sourced bio-based materials

Biogenic carbon claims must be assessed with sourcing, forest management, service life, moisture protection, fire safety and end-of-life assumptions.

Reclaimed and Reused Materials

Examples include:

• Reused steel
• Reclaimed bricks
• Reused raised flooring
• Reclaimed timber
• Salvaged façade components

Reused products may avoid some new manufacturing impacts but still require inspection, testing, documentation and safe installation.

Practical Embodied Carbon Reduction Strategies

1. Retain existing structures where practical
2. Set a project carbon baseline early
3. Establish material-specific carbon limits
4. Design with fewer materials and finishes
5. Use EPDs during procurement
6. Reduce over-ordering and site waste
7. Source products closer to the project where appropriate
8. Design components for repair, reuse and disassembly
9. Track substitutions through change control
10. Report actual quantities rather than relying only on design estimates

These actions support construction decarbonization, circular construction and sustainable procurement.

How Does Low-Carbon Material Selection Affect Construction Safety?

Changing a material or method can create new hazards:

• Silica dust from concrete and masonry
• Skin and eye exposure to wet cement
• Dust from recycled or reclaimed products
• Manual-handling demands
• Lifting requirements for prefabricated elements
• Adhesives, coatings and chemical treatments
• Combustibility and fire performance
• Cutting and installation methods
• Hidden contaminants in reclaimed materials
• Structural and quality-control requirements

OSHA's construction silica standard applies to occupational exposures to respirable crystalline silica, while OSHA also identifies wet cement as a potential source of burns and dermatitis.

A low-carbon product is not automatically a low-risk product. Environmental improvement and occupational risk prevention must be evaluated together.

How Should Contractors and Procurement Teams Compare Suppliers?

Ask suppliers for:

• Product-specific EPDs
• Product category rules used
• Declared unit
• Lifecycle stages included
• GWP results
• Manufacturing location
• Recycled content
• Responsible-sourcing evidence
• Durability and warranty data
• Safety data sheets where applicable
• Installation and end-of-life guidance

The GHG Protocol provides standards for assessing product-level and value-chain emissions, including Scope 3 emissions associated with purchased goods and services.

Build Carbon and Environmental Competence

Understanding embodied carbon requires more than recognising environmentally preferable products. Professionals must also evaluate environmental risk, compliance, lifecycle impacts, procurement decisions and workplace controls.

Develop these capabilities through the Environmental Safety & Sustainability (ESG) course and strengthen your ability to support safer, more resource-efficient and lower-carbon operations.

Reducing embodied carbon in construction begins before materials arrive on site. Teams should reduce unnecessary material use, compare equivalent products using credible lifecycle data and verify that every lower-carbon alternative remains safe, durable and suitable.

The best material choice balances carbon reduction, technical performance, worker safety, lifecycle value and transparent evidence.