OENG1118 Sustainable Engineering Practice and Design - Week 5: Life Cycle Assessment (LCA) Goal and Scope

OENG1118 Sustainable Engineering Practice and Design: Week 5 - Life Cycle Assessment (LCA) Goal and Scope # Overview and the Iterative Nature of LCA * Primary Goal of LCA Goal and Scope: The goal and scope definition phase is the first step in a Life Cycle Assessment, establishing the framework, boundaries, and objectives of the study. * Skills to be Acquired: 1. Formulate a comprehensive goal statement. 2. Formulate a functional unit based on product services. 3. Draw a system boundary diagram including unit processes, elementary flows, and intermediate flows (materials, energy, emissions, and other releases). * Iterative Process Take-home Message: An LCA is not a linear process. As more information is learned about the product and available data, the goal must be adjusted to ensure the study remains consistent and congruent with the findings. # Formulating the Goal Statement * Decision Support: The goal statement is used to decide which life cycle stages, processes, flows, environmental impacts, and language styles are to be included in the report. * Component 1: Intended Application: Specifies if the information supports marketing claims, product design, process improvement, policy decisions, certification, strategic planning, or priority setting. * Component 2: Reason for the Study: Analysts must ask "Why?" multiple times to reach the root cause. Reasons may include: 1. High production costs. 2. Significant environmental impact. 3. Shrinking market share. 4. High operational or environmental risk. 5. This section must specify the exact questions the study aims to address. * Component 3: Intended Audience: Identifies for whom the report is written and who will make decisions based on the results. Examples include: 1. Manufacturers. 2. Users/Consumers. 3. Government/Regulators. 4. Investors. # The Functional Unit * Definition: The functional unit quantifies the primary function of the product or service being studied, allowing for a fair comparison between different systems. * Identifying Functions (Example: A pair of shoes): 1. Protect feet from impact forces. 2. Protect feet from dirt. 3. Protect feet from water. 4. Provide comfort. 5. Fashion and aesthetics. 6. Contribution to a collection. * Primary vs. Secondary Functions: The primary function is the main service identified according to the goal. In the shoe example, it might be protecting feet from ground impact over a specific distance. * Steps to Define a Functional Unit: 1. Distinguish between primary and secondary functions. 2. Consider the size (how much service is provided) and duration (how long it takes or how long the product lasts before replacement). 3. Write a single sentence quantifying the primary function. * Numerical Comparison Case Study: High-Quality vs. Low-Quality Shoes: 1. Functional Unit: Protecting feet from 700 N700\,N of ground impact during 1000 km1000\,km of walking. 2. High-quality shoe service/pair: 1000 km1000\,km at 700 N700\,N. Materials per pair: 600 g600\,g leather, 500 g500\,g rubber, 10 g10\,g thread, 5 g5\,g adhesive. 3. Low-quality shoe service/pair: 200 km200\,km at 700 N700\,N. Materials per pair: 200 g200\,g leather, 300 g300\,g rubber, 200 g200\,g canvas, 5 g5\,g adhesive. 4. Reference Flow Comparison: To meet the functional unit of 1000 km1000\,km: - High-quality requirement: 1 pair. Total materials: 600 g600\,g leather, 500 g500\,g rubber, 10 g10\,g thread, 5 g5\,g adhesive. - Low-quality requirement: 5 pairs. Total materials: 1000 g1000\,g leather, 1500 g1500\,g rubber, 1000 g1000\,g canvas, 25 g25\,g adhesive. * Reference Flow: The specific amount of product needed to fulfill the functional unit (e.g., 5 pairs for the low-quality option). # System Boundary Diagrams * Purpose: A mapping of processes, product flows, and major environmental input/output flows. * Key Concepts: 1. Unit Process: The smallest element considered in the life cycle inventory analysis for which input and output data are quantified. 2. Node: Each node in the diagram represents a process. 3. Reference Flow Placement: Usually shown at the use stage. * Standard Exclusions: 1. Capital equipment and maintenance (though some modern models may include them). 2. Human labor. 3. Accidents. 4. Internal transportation of materials. * Style Conventions for Diagrams: 1. Use a dashed box for the system boundary. 2. Use solid boxes for unit processes. 3. Ensure arrow directions are correct: Raw materials go in; Waste goes out. 4. Shared processes should be disconnected and shaded/colored differently. 5. Excluded processes should be disconnected and clearly captioned. 6. The functional unit should be explicitly shown on the diagram. 7. Use Microsoft Visio for creation. * Elementary vs. Intermediate Flows: In a full LCA, elementary flows (inputs from the environment without prior transformation) are often excluded from the diagram for clarity; however, in a streamlined LCA, major elementary flows are included. # Case Study Examples of System Boundaries * Generic Industrial Life Cycle Stages: Extraction of raw materials $\rightarrow$ Material processing $\rightarrow$ Product manufacture $\rightarrow$ Construction $\rightarrow$ Use $\rightarrow$ Maintenance $\rightarrow$ End of life (Demolition/Recycling/Reuse/Disposal). * Cross-Laminated Timber (CLT) Building: 1. Austria Processes: Forestry, wood harvesting, debarking/sawing/drying, CLT manufacture. 2. Shared/Infrastructure Processes: Fossil fuel extraction, electricity generation, transport, capital equipment, internal labor. 3. Australia Processes: Shipping/Import, building construction, use/maintenance, demolition, recycling, or landfill. * Biohybrid Master-blend (Thermoplastic Starch - TPS): 1. Inputs: Cassava farming/processing (Thailand), Maize farming/drying (China), Pesticides, Fertilizers, LDPE production, PP production. 2. Processing: TPS processing (China), Film blowing, Injection moulding. 3. Disposal Path: Incineration (Waste to energy), Landfill, Recycling (avoiding virgin LDPE/PP production). * Aviation Bio-fuel (Mallee Plantation): 1. Boundary: Includes plantation establishment, mallee harvesting, pyrolysis reactor, hydro-processing, and distribution for use in a commercial passenger flight (Perth to Sydney, A330-200). 2. Functional Unit: 1 commercial passenger flight (Perth to Sydney). # Quiz and Discussion Review * Intended Application Benefit: Catering a report to a specific audience (e.g., policy developers) ensures the findings are actionable and relevant to their specific decision-making criteria. * Defining Functions Practice: 1. Pet: Primary function is companionship. Functional Unit: "Live domestic companion for 10 years." 2. Smartphone: Primary function is communication. Functional Unit: "Verbal conversation at 60 dBA60\,dBA for 1000 hours1000\,hours." 3. Indoor Paint: Primary function is coverage. Functional Unit: "Cover 20 m220\,m^2 of surface with 98%98\% opacity and an 8080 Rockwell hardness for 5 years5\,years." 4. Light Bulb: Primary function is artificial light emission. Functional Unit: "500 lumens500\,lumens of artificial light for 10 years10\,years." 5. Soft Drink Bottle: Primary function is delivering beverage. Functional Unit: "Deliver to a consumer 1 L1\,L of beverage at 700 kPa700\,kPa within 1 year1\,year." * Defining Requirements: To define a functional unit, the primary functions, the service size, and duration must be known. Secondary functions are generally not required for the core definition but may be noted. # Skills and Assessment Standards * Summary of Skills: 1. Goal Statement: Include intended application, reasons, and intended audience. 2. Functional Unit: Include product/system, primary/secondary functions, size/time of service, and reference flow. 3. Boundary Diagram: Map processing, production, distribution, use, end-of-life, recovery, and disposal. * SOLO Taxonomy: Mentions the assessment standards used to evaluate student depth of understanding, categorized from unistructural to extended abstract levels.