lifecycle-carbon-calculator

Lifecycle Carbon Calculator for Construction

Overview

Calculate embodied carbon (EC) and lifecycle carbon emissions for construction materials, assemblies, and projects. Support sustainable design decisions and carbon reduction targets.

Business Case

Carbon calculation supports:

• Regulatory Compliance: Meet carbon reporting requirements
• Green Certifications: LEED, BREEAM, Living Building Challenge
• Design Optimization: Choose lower-carbon alternatives
• Sustainability Goals: Track progress toward net-zero

Technical Implementation

from dataclasses import dataclass, field
from typing import List, Dict, Any, Optional
from enum import Enum
import pandas as pd

class LifecycleStage(Enum):
    A1_A3 = "Product Stage (A1-A3)"  # Raw materials, transport, manufacturing
    A4 = "Transport to Site (A4)"
    A5 = "Construction (A5)"
    B1_B7 = "Use Stage (B1-B7)"  # Maintenance, repair, replacement
    C1_C4 = "End of Life (C1-C4)"  # Demolition, transport, disposal
    D = "Beyond Lifecycle (D)"  # Reuse, recycling potential

@dataclass
class MaterialCarbon:
    material_id: str
    name: str
    category: str
    unit: str
    carbon_a1_a3: float  # kgCO2e per unit
    carbon_a4: float
    carbon_a5: float
    carbon_b: float
    carbon_c: float
    carbon_d: float  # Usually negative (credit)
    density: float  # kg/m³ if applicable
    source: str
    epd_url: str = ""

@dataclass
class AssemblyCarbon:
    assembly_id: str
    name: str
    materials: List[Dict[str, Any]]
    total_carbon: float
    carbon_by_stage: Dict[str, float]

@dataclass
class ProjectCarbon:
    project_id: str
    name: str
    gross_area: float
    assemblies: List[AssemblyCarbon]
    total_embodied_carbon: float
    carbon_per_area: float
    carbon_by_stage: Dict[str, float]
    carbon_by_category: Dict[str, float]
    benchmark_comparison: Dict[str, Any]

class LifecycleCarbonCalculator:
    """Calculate lifecycle carbon for construction."""

    # Sample material carbon data (kgCO2e per unit)
    DEFAULT_MATERIALS = {
        'concrete_30mpa': MaterialCarbon(
            material_id='C30', name='Concrete 30MPa', category='Concrete',
            unit='m³', carbon_a1_a3=300, carbon_a4=5, carbon_a5=2,
            carbon_b=0, carbon_c=10, carbon_d=-20, density=2400,
            source='EPD Database'
        ),
        'concrete_40mpa': MaterialCarbon(
            material_id='C40', name='Concrete 40MPa', category='Concrete',
            unit='m³', carbon_a1_a3=350, carbon_a4=5, carbon_a5=2,
            carbon_b=0, carbon_c=10, carbon_d=-20, density=2400,
            source='EPD Database'
        ),
        'steel_rebar': MaterialCarbon(
            material_id='REBAR', name='Steel Reinforcing Bar', category='Steel',
            unit='kg', carbon_a1_a3=1.99, carbon_a4=0.05, carbon_a5=0.02,
            carbon_b=0, carbon_c=0.05, carbon_d=-0.5, density=7850,
            source='WorldSteel EPD'
        ),
        'steel_structural': MaterialCarbon(
            material_id='STEEL', name='Structural Steel', category='Steel',
            unit='kg', carbon_a1_a3=1.55, carbon_a4=0.05, carbon_a5=0.03,
            carbon_b=0, carbon_c=0.05, carbon_d=-0.8, density=7850,
            source='AISC EPD'
        ),
        'timber_clt': MaterialCarbon(
            material_id='CLT', name='Cross-Laminated Timber', category='Timber',
            unit='m³', carbon_a1_a3=-500, carbon_a4=10, carbon_a5=5,
            carbon_b=0, carbon_c=50, carbon_d=-100, density=500,
            source='AWC EPD'
        ),
        'gypsum_board': MaterialCarbon(
            material_id='GYP', name='Gypsum Board 12.5mm', category='Finishes',
            unit='m²', carbon_a1_a3=3.2, carbon_a4=0.2, carbon_a5=0.1,
            carbon_b=0, carbon_c=0.3, carbon_d=-0.1, density=10,
            source='EUROGYPSUM EPD'
        ),
        'insulation_mineral': MaterialCarbon(
            material_id='INS_MW', name='Mineral Wool Insulation', category='Insulation',
            unit='m³', carbon_a1_a3=45, carbon_a4=2, carbon_a5=1,
            carbon_b=0, carbon_c=5, carbon_d=-2, density=40,
            source='EURIMA EPD'
        ),
        'glass_double': MaterialCarbon(
            material_id='GLASS', name='Double Glazed Unit', category='Glazing',
            unit='m²', carbon_a1_a3=35, carbon_a4=1, carbon_a5=0.5,
            carbon_b=0, carbon_c=2, carbon_d=-5, density=25,
            source='Glass for Europe EPD'
        ),
        'aluminum': MaterialCarbon(
            material_id='ALU', name='Aluminum Profile', category='Metals',
            unit='kg', carbon_a1_a3=8.0, carbon_a4=0.1, carbon_a5=0.05,
            carbon_b=0, carbon_c=0.1, carbon_d=-4.0, density=2700,
            source='EAA EPD'
        ),
    }

    # Building type benchmarks (kgCO2e/m²)
    BENCHMARKS = {
        'Office': {'typical': 500, 'good': 350, 'best': 200},
        'Residential': {'typical': 400, 'good': 280, 'best': 150},
        'Retail': {'typical': 450, 'good': 320, 'best': 180},
        'Industrial': {'typical': 350, 'good': 250, 'best': 150},
        'Healthcare': {'typical': 700, 'good': 500, 'best': 350},
    }

    def __init__(self):
        self.materials: Dict[str, MaterialCarbon] = dict(self.DEFAULT_MATERIALS)
        self.assemblies: Dict[str, AssemblyCarbon] = {}

    def add_material(self, material: MaterialCarbon):
        """Add or update a material."""
        self.materials[material.material_id] = material

    def calculate_material_carbon(self, material_id: str, quantity: float,
                                   stages: List[LifecycleStage] = None) -> Dict:
        """Calculate carbon for a material quantity."""
        if material_id not in self.materials:
            raise ValueError(f"Unknown material: {material_id}")

        material = self.materials[material_id]

        if stages is None:
            stages = list(LifecycleStage)

        carbon_by_stage = {}
        total = 0

        for stage in stages:
            if stage == LifecycleStage.A1_A3:
                carbon = material.carbon_a1_a3 * quantity
            elif stage == LifecycleStage.A4:
                carbon = material.carbon_a4 * quantity
            elif stage == LifecycleStage.A5:
                carbon = material.carbon_a5 * quantity
            elif stage == LifecycleStage.B1_B7:
                carbon = material.carbon_b * quantity
            elif stage == LifecycleStage.C1_C4:
                carbon = material.carbon_c * quantity
            elif stage == LifecycleStage.D:
                carbon = material.carbon_d * quantity
            else:
                carbon = 0

            carbon_by_stage[stage.value] = carbon
            total += carbon

        return {
            'material_id': material_id,
            'material_name': material.name,
            'quantity': quantity,
            'unit': material.unit,
            'total_carbon': total,
            'carbon_by_stage': carbon_by_stage
        }

    def create_assembly(self, assembly_id: str, name: str,
                        components: List[Dict]) -> AssemblyCarbon:
        """Create an assembly from multiple materials."""
        total_carbon = 0
        carbon_by_stage = {stage.value: 0 for stage in LifecycleStage}
        material_details = []

        for comp in components:
            material_id = comp['material_id']
            quantity = comp['quantity']

            result = self.calculate_material_carbon(material_id, quantity)
            total_carbon += result['total_carbon']

            for stage, carbon in result['carbon_by_stage'].items():
                carbon_by_stage[stage] += carbon

            material_details.append({
                'material': result['material_name'],
                'quantity': quantity,
                'unit': result['unit'],
                'carbon': result['total_carbon']
            })

        assembly = AssemblyCarbon(
            assembly_id=assembly_id,
            name=name,
            materials=material_details,
            total_carbon=total_carbon,
            carbon_by_stage=carbon_by_stage
        )

        self.assemblies[assembly_id] = assembly
        return assembly

    def calculate_project_carbon(self, project_id: str, project_name: str,
                                  gross_area: float, building_type: str,
                                  quantities: List[Dict]) -> ProjectCarbon:
        """Calculate total project carbon."""
        assemblies = []
        total_carbon = 0
        carbon_by_stage = {stage.value: 0 for stage in LifecycleStage}
        carbon_by_category = {}

        for qty in quantities:
            if 'assembly_id' in qty:
                # Use predefined assembly
                if qty['assembly_id'] in self.assemblies:
                    assembly = self.assemblies[qty['assembly_id']]
                    multiplier = qty.get('multiplier', 1)
                    scaled_carbon = assembly.total_carbon * multiplier

                    assemblies.append(AssemblyCarbon(
                        assembly_id=assembly.assembly_id,
                        name=assembly.name,
                        materials=assembly.materials,
                        total_carbon=scaled_carbon,
                        carbon_by_stage={k: v * multiplier for k, v in assembly.carbon_by_stage.items()}
                    ))
                    total_carbon += scaled_carbon

            elif 'material_id' in qty:
                # Direct material
                result = self.calculate_material_carbon(
                    qty['material_id'], qty['quantity']
                )
                total_carbon += result['total_carbon']

                for stage, carbon in result['carbon_by_stage'].items():
                    carbon_by_stage[stage] += carbon

                # Track by category
                material = self.materials[qty['material_id']]
                cat = material.category
                carbon_by_category[cat] = carbon_by_category.get(cat, 0) + result['total_carbon']

        # Calculate metrics
        carbon_per_area = total_carbon / gross_area if gross_area > 0 else 0

        # Compare to benchmarks
        benchmark = self.BENCHMARKS.get(building_type, self.BENCHMARKS['Office'])
        benchmark_comparison = {
            'carbon_per_area': carbon_per_area,
            'typical_benchmark': benchmark['typical'],
            'good_benchmark': benchmark['good'],
            'best_benchmark': benchmark['best'],
            'vs_typical': (carbon_per_area / benchmark['typical'] - 1) * 100,
            'rating': self._get_rating(carbon_per_area, benchmark)
        }

        return ProjectCarbon(
            project_id=project_id,
            name=project_name,
            gross_area=gross_area,
            assemblies=assemblies,
            total_embodied_carbon=total_carbon,
            carbon_per_area=carbon_per_area,
            carbon_by_stage=carbon_by_stage,
            carbon_by_category=carbon_by_category,
            benchmark_comparison=benchmark_comparison
        )

    def _get_rating(self, carbon: float, benchmark: Dict) -> str:
        """Get rating based on benchmark comparison."""
        if carbon <= benchmark['best']:
            return 'A (Best Practice)'
        elif carbon <= benchmark['good']:
            return 'B (Good Practice)'
        elif carbon <= benchmark['typical']:
            return 'C (Typical)'
        else:
            return 'D (Above Typical)'

    def compare_alternatives(self, base_project: ProjectCarbon,
                              alternatives: List[Dict]) -> pd.DataFrame:
        """Compare carbon of design alternatives."""
        comparisons = [{
            'Option': 'Base Design',
            'Total Carbon (tCO2e)': base_project.total_embodied_carbon / 1000,
            'Carbon/m² (kgCO2e)': base_project.carbon_per_area,
            'vs Base': '0%',
            'Rating': base_project.benchmark_comparison['rating']
        }]

        for alt in alternatives:
            project = self.calculate_project_carbon(
                alt['id'], alt['name'], alt['gross_area'],
                alt.get('building_type', 'Office'), alt['quantities']
            )

            change = (project.total_embodied_carbon - base_project.total_embodied_carbon) / base_project.total_embodied_carbon * 100

            comparisons.append({
                'Option': alt['name'],
                'Total Carbon (tCO2e)': project.total_embodied_carbon / 1000,
                'Carbon/m² (kgCO2e)': project.carbon_per_area,
                'vs Base': f'{change:+.1f}%',
                'Rating': project.benchmark_comparison['rating']
            })

        return pd.DataFrame(comparisons)

    def suggest_reductions(self, project: ProjectCarbon) -> List[Dict]:
        """Suggest carbon reduction opportunities."""
        suggestions = []

        # Analyze by category
        if 'Concrete' in project.carbon_by_category:
            concrete_carbon = project.carbon_by_category['Concrete']
            if concrete_carbon > project.total_embodied_carbon * 0.3:
                suggestions.append({
                    'category': 'Concrete',
                    'current_carbon': concrete_carbon,
                    'suggestion': 'Consider low-carbon concrete (GGBS/PFA replacement)',
                    'potential_reduction': '20-40%',
                    'impact': concrete_carbon * 0.3
                })

        if 'Steel' in project.carbon_by_category:
            steel_carbon = project.carbon_by_category['Steel']
            if steel_carbon > project.total_embodied_carbon * 0.2:
                suggestions.append({
                    'category': 'Steel',
                    'current_carbon': steel_carbon,
                    'suggestion': 'Specify high recycled content steel',
                    'potential_reduction': '10-25%',
                    'impact': steel_carbon * 0.2
                })

        # Benchmark-based suggestions
        if project.benchmark_comparison['vs_typical'] > 0:
            suggestions.append({
                'category': 'Overall',
                'current_carbon': project.total_embodied_carbon,
                'suggestion': 'Project exceeds typical benchmark - review high-carbon elements',
                'potential_reduction': f"{abs(project.benchmark_comparison['vs_typical']):.0f}%",
                'impact': project.total_embodied_carbon * abs(project.benchmark_comparison['vs_typical']) / 100
            })

        return sorted(suggestions, key=lambda x: -x['impact'])

    def generate_report(self, project: ProjectCarbon) -> str:
        """Generate carbon assessment report."""
        lines = ["# Embodied Carbon Assessment Report", ""]
        lines.append(f"**Project:** {project.name}")
        lines.append(f"**Gross Area:** {project.gross_area:,.0f} m²")
        lines.append(f"**Assessment Date:** {pd.Timestamp.now().strftime('%Y-%m-%d')}")
        lines.append("")

        # Summary
        lines.append("## Carbon Summary")
        lines.append(f"- **Total Embodied Carbon:** {project.total_embodied_carbon/1000:,.0f} tCO2e")
        lines.append(f"- **Carbon Intensity:** {project.carbon_per_area:,.0f} kgCO2e/m²")
        lines.append(f"- **Rating:** {project.benchmark_comparison['rating']}")
        lines.append("")

        # By lifecycle stage
        lines.append("## Carbon by Lifecycle Stage")
        for stage, carbon in project.carbon_by_stage.items():
            if carbon != 0:
                pct = carbon / project.total_embodied_carbon * 100
                lines.append(f"- {stage}: {carbon/1000:,.1f} tCO2e ({pct:.1f}%)")
        lines.append("")

        # By category
        lines.append("## Carbon by Material Category")
        for cat, carbon in sorted(project.carbon_by_category.items(), key=lambda x: -x[1]):
            pct = carbon / project.total_embodied_carbon * 100
            lines.append(f"- {cat}: {carbon/1000:,.1f} tCO2e ({pct:.1f}%)")
        lines.append("")

        # Benchmark
        lines.append("## Benchmark Comparison")
        bc = project.benchmark_comparison
        lines.append(f"- Project: {bc['carbon_per_area']:.0f} kgCO2e/m²")
        lines.append(f"- Typical: {bc['typical_benchmark']} kgCO2e/m²")
        lines.append(f"- Good Practice: {bc['good_benchmark']} kgCO2e/m²")
        lines.append(f"- Best Practice: {bc['best_benchmark']} kgCO2e/m²")
        lines.append("")

        # Reduction opportunities
        suggestions = self.suggest_reductions(project)
        if suggestions:
            lines.append("## Reduction Opportunities")
            for sug in suggestions[:5]:
                lines.append(f"\n### {sug['category']}")
                lines.append(f"- **Suggestion:** {sug['suggestion']}")
                lines.append(f"- **Potential Reduction:** {sug['potential_reduction']}")
                lines.append(f"- **Impact:** {sug['impact']/1000:,.1f} tCO2e")

        return "\n".join(lines)