Introduction Life-Cycle Assessment and Multi-Criteris Decision Analysis of Roofing System
This report evaluates six roofing materials—Asphalt, Fiberglass, Steel, Aluminum, Soil, and Vegetation—using Life-Cycle Assessment (LCA) and Multi-Criteria Decision Analysis (MCDA). The study examines energy consumption, CO₂ emissions, NOₓ emissions, SO₂ emissions, and costs across the life cycle of each material. Materials are ranked using the Analytic Hierarchy Process (AHP) based on their environmental and economic performance. The findings suggest that Green Roof materials (Soil and Vegetation) offer long-term sustainability benefits despite higher initial costs. Sensitivity analysis shows that these conclusions are robust.
1. Introduction
Roofing systems play an essential role in building protection and influence energy efficiency, sustainability, and long-term costs. As concerns about climate change grow, selecting environmentally friendly roofing materials becomes increasingly important. This study evaluates six roofing materials:
– Asphalt
– Fiberglass
– Steel
– Aluminum
– Soil
– Vegetation
We assess their environmental impact, cost-effectiveness, and sustainability benefits using LCA and MCDA (AHP).
2. Scope and Goal Definition
The goal of this study is to:
– Compare the environmental impacts (CO₂, NOₓ, SO₂ emissions, energy use) of the roofing materials.
– Assess costs (initial, maintenance, operational, end-of-life).
– Rank materials using MCDA (AHP).
– Perform sensitivity analysis to test decision reliability.
We evaluate the full life cycle of each material—from production to disposal—for a comprehensive sustainability assessment.
3. Methodology
Life-Cycle Assessment (LCA)LCA measures the environmental impact of materials across four stages:
1. Production
2. Installation
3. Usage
4. End-of-life disposal
Key indicators include:
– Energy consumption (MJ/t)
– CO₂ emissions (kg/m³)
– NOₓ and SO₂ emissions (kg/m³)
LCA follows ISO 14040 & 14044 standards.
Multi-Criteria Decision Analysis (MCDA – AHP)
AHP ranks materials based on:
– Environmental impact (CO₂, NOₓ, SO₂ emissions, energy use)
– Cost analysis (initial, maintenance, operational, and end-of-life)
Materials are compared pairwise, and weights are assigned to each factor based on their importance.
Sensitivity Analysis
We test the reliability of the rankings by analyzing variations in energy consumption, CO₂ emissions, and costs under different scenarios.
4. Data Inventory and Assumptions
| Material | Energy (MJ/t) | CO₂ (kg/m³) | NOₓ (kg/m³) | SO₂ (kg/m³) | Cost ($/t) |
| Asphalt | 600 | 27 | 0.05 | 0.02 | 150 |
| Fiberglass | 1200 | 45 | 0.07 | 0.03 | 200 |
| Steel | 2000 | 40 | 0.10 | 0.05 | 2500 |
| Aluminum | 15000 | 70 | 0.20 | 0.10 | 3200 |
| Soil | 50 | 5 | 0.02 | 0.01 | 30 |
| Vegetation | 30 | 3 | 0.01 | 0.005 | 20 |
5. Results and Analysis
LCA Results
- Green Roofs (Soil and Vegetation) have the lowest CO₂ emissions and require less energy.
– Asphalt and Fiberglass have higher emissions due to energy-intensive manufacturing.
MCDA Results (AHP Ranking)
- Green Roofs (Soil and Vegetation) rank highest due to their sustainability benefits.
– Steel and Aluminum rank lower due to high energy consumption and emissions.
Sensitivity Analysis
- The rankings remain consistent even with variations in cost and energy data, confirming the robustness of the results.
Cost Analysis
- Green Roofs have higher initial costs but lower operational expenses.
– Asphalt is cheaper initially but has higher maintenance and environmental costs over time.
6. Conclusion
- Green Roofs (Soil and Vegetation) are the most sustainable option, offering long-term environmental and economic benefits, despite higher initial costs.
– Considering life-cycle costs is essential for making informed decisions.
– Decision-makers should prioritize sustainability when selecting roofing materials.
This study provides a comprehensive decision-making framework for selecting roofing systems using LCA and MCDA, helping to balance both environmental and economic factors.