LCA for Construction and Buildings

Construction is the world's largest consumer of raw materials and a major contributor to global carbon emissions. Building LCA has emerged as the fastest-growing application of Life Cycle Assessment, driven by green building certification, embodied carbon regulations, and climate commitments.

Why LCA in Construction?

The built environment presents unique challenges and opportunities:

Scale of impact: Buildings account for ~40% of global energy consumption and ~30% of CO₂ emissions.

Long service life: 50-100 year building lifetimes mean decisions today have long-term consequences.

Material intensity: Buildings consume half of all extracted materials globally.

Emerging regulation: Embodied carbon limits are being mandated in jurisdictions from California to the EU.

Professional demand: Architects, engineers, and developers need LCA skills for competitive projects.

Two Levels of Construction LCA

1. Product-Level: Construction Product EPDs

Individual products (concrete, steel, insulation) are assessed following EN 15804 and relevant PCRs. Results appear in EPDs that feed into whole-building assessment.

2. Building-Level: Whole Building LCA (WBLCA)

Entire buildings are assessed using product EPDs and building-specific data for assembly, operation, and end-of-life.

Both levels are interconnected—WBLCA depends on product EPD data.

The EN 15804 Framework

EN 15804 is the foundational European standard for construction product sustainability:

Life Cycle Modules

EN 15804 defines standardized life cycle modules:

Impact Categories (EN 15804+A2:2019)

The updated EN 15804 requires these impact categories:

Core environmental indicators:

• Global Warming Potential (GWP-total, GWP-fossil, GWP-biogenic, GWP-luluc)
• Ozone Depletion Potential (ODP)
• Acidification Potential (AP)
• Eutrophication Potential (EP-freshwater, EP-marine, EP-terrestrial)
• Photochemical Ozone Creation Potential (POCP)
• Abiotic Depletion Potential (ADP-minerals, ADP-fossil)
• Water Use

Resource use indicators:

• Renewable/non-renewable primary energy
• Secondary material use
• Renewable/non-renewable secondary fuels
• Net fresh water use

Waste and output flows:

• Hazardous/non-hazardous waste
• Radioactive waste
• Components for reuse
• Materials for recycling/energy recovery

Whole Building LCA Methodology

System Boundary

WBLCA typically includes:

Always included (Modules A-C):

• Building structure and envelope
• Foundations
• Interior finishes
• Building services (HVAC, plumbing, electrical)

Often included:

• Site works and landscaping
• Operational energy (Module B6)
• Operational water (Module B7)
• Maintenance and replacement (B2-B5)

Sometimes excluded:

• Furniture and equipment
• Temporary works during construction
• Pre-existing infrastructure

Reference Study Period

Buildings are typically assessed over a Reference Study Period (RSP):

• 50 years is common for regulatory compliance
• 60 years used in some standards (e.g., RICS)
• Actual expected life for specific applications

Components with shorter lives than the RSP require replacement (Module B4).

Functional Equivalent

For building comparison:

Poor comparison basis: "per building"

• Buildings vary in size, function, occupancy

Better comparison basis: "per m² gross floor area over 50 years"

• Normalizes for size
• Accounts for service life

Additional parameters:

• Building function (office, residential, retail)
• Climate zone
• Occupancy assumptions
• Energy performance level

Key Impact Categories for Buildings

Embodied Carbon (Modules A1-A5, B4, C)

Embodied carbon has become the primary focus:

Why it matters:

• Operational carbon is reducing as grids decarbonize
• Embodied carbon is "locked in" at construction
• Represents 50-80% of total carbon for high-performance buildings
• Increasingly regulated

Typical breakdown by material (new office building):

Operational Carbon (Module B6)

Energy use during building operation:

Key factors:

• Building energy performance (envelope, systems)
• Energy source carbon intensity
• Occupant behavior
• Climate

Trend: As buildings become more efficient and grids cleaner, operational carbon's share decreases—making embodied carbon relatively more important.

Data Sources and Tools

EPD Databases

WBLCA Tools

Generic Data

When EPDs aren't available:

• Industry-average data (ICE Database, Athena)
• Generic database values (ecoinvent, GaBi)
• Conservative assumptions

Case Study: Commercial Office Building

Project Profile

• Type: 10-story office building
• Location: Seattle, USA
• Size: 25,000 m² GFA
• Structure: Steel frame, concrete core
• Target: LEED Gold, embodied carbon reduction

Baseline Assessment

Initial design embodied carbon: 450 kg CO₂e/m²

Breakdown by module:

• A1-A3 (Products): 380 kg CO₂e/m² (84%)
• A4-A5 (Construction): 30 kg CO₂e/m² (7%)
• B4 (Replacement): 25 kg CO₂e/m² (6%)
• C (End of life): 15 kg CO₂e/m² (3%)

Breakdown by system:

• Structure: 220 kg CO₂e/m² (49%)
• Envelope: 90 kg CO₂e/m² (20%)
• Interiors: 65 kg CO₂e/m² (14%)
• MEP: 50 kg CO₂e/m² (11%)
• Site: 25 kg CO₂e/m² (6%)

Reduction Strategies Evaluated

Final Design

Revised embodied carbon: 290 kg CO₂e/m² (35% reduction)

Primary changes:

• Hybrid mass timber and steel structure
• 35% supplementary cementite materials in concrete
• High recycled content aluminum
• Optimized façade-to-floor ratio

Regulatory Landscape

Current Regulations

EU: Level(s) framework recommends WBLCA; some countries mandating Netherlands: MPG limit of 0.8 for residential, decreasing over time France: RE2020 includes embodied carbon limits Denmark: Embodied carbon limits since 2023 California: Buy Clean Act for public projects Vancouver/Toronto: Embodied carbon reporting required

Emerging Trends

• More jurisdictions mandating WBLCA
• Limits tightening over time
• Scope expanding (all building types)
• EPD requirements for materials

Certification Systems

LEED v4.1

MR Credit: Building Life-Cycle Impact Reduction

• Option 1: Historic building reuse
• Option 2: Renovation of abandoned building
• Option 3: Building and material reuse
• Option 4: WBLCA (demonstrates impact reduction vs. baseline)

BREEAM

Mat 01: Responsible sourcing (includes LCA approach) Mat 06: Material efficiency (WBLCA encouraged)

Living Building Challenge

Materials Petal: Requires embodied carbon reduction, Red List avoidance

Challenges and Limitations

Data Gaps

• Not all products have EPDs
• Generic data may not reflect specific products
• MEP systems data often limited
• Renovation assessment is complex

Methodology Variations

• Different tools give different results
• Assumptions vary (RSP, replacements, scenarios)
• System boundaries may differ
• Comparability requires careful harmonization

Practical Constraints

• LCA often happens too late in design
• Results may conflict with other priorities (cost, aesthetics)
• Contractor capability varies
• Verification and compliance processes developing

Getting Started

For Architects/Engineers

1. Learn basic LCA concepts (this course)
2. Get trained on a WBLCA tool (One Click LCA, Tally)
3. Start with early-stage massing studies
4. Integrate into design process at schematic phase
5. Collaborate with sustainability consultants

For Material Specifiers

1. Understand EPD reading and interpretation
2. Use EC3 to compare products
3. Specify EPD requirements in projects
4. Track embodied carbon in specifications

For Building Owners/Developers

1. Set embodied carbon targets
2. Require WBLCA in design team contracts
3. Track portfolio performance
4. Support EPD requirements for materials

Key Takeaways

1. Construction LCA operates at both product (EPD) and building (WBLCA) levels
2. EN 15804 provides standardized modules (A-D) for consistent assessment
3. Embodied carbon is now the focus as operational carbon decreases
4. Structure and concrete typically dominate embodied carbon
5. Regulations are expanding—WBLCA skills are essential
6. Early integration in design yields the biggest reduction opportunities

Resource List

Standards and Guidelines

• EN 15804:2012+A2:2019 (Construction product EPDs)
• EN 15978 (Whole building LCA)
• ISO 21930 (Construction works EPDs)
• RICS Whole Life Carbon Assessment

Tools and Databases

• EC3 Tool
• One Click LCA
• ÖKOBAUDAT
• Athena Impact Estimator

Learning Resources

• Carbon Leadership Forum resources
• UKGBC Embodied Carbon Primer
• Architecture 2030 Carbon Smart Materials Palette

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This lesson provides an overview. Building LCA involves additional complexity around specific building types, local regulations, and tool-specific methodologies.