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This lesson covers life cycle assessment (LCA), a systematic method for evaluating the environmental impact of a product throughout its entire life, as required by AQA GCSE D&T (8552), Section 3.2.3. LCA is a powerful tool that helps designers make informed, evidence-based decisions about materials, manufacturing processes, and end-of-life strategies.
A life cycle assessment (LCA) is a method for evaluating the total environmental impact of a product from "cradle to grave" — from the extraction of raw materials through to final disposal.
The key principle is that you cannot fully assess the environmental impact of a product by looking at only one stage (e.g. just manufacturing or just disposal). You must consider the entire life cycle.
The diagram below shows the five stages of a product's life cycle from cradle to grave, with the cradle-to-cradle loop back to the start:
graph LR
A["1. Raw Material\nExtraction\n(Cradle)"] --> B["2. Processing &\nManufacturing\n(Gate)"]
B --> C["3. Transport &\nDistribution"]
C --> D["4. Use &\nMaintenance"]
D --> E["5. End of Life\n(Grave)"]
E -->|"♻ Cradle to Cradle:\nMaterials recovered\n& reused"| A
| Stage | Also Known As | What Happens | Environmental Impacts |
|---|---|---|---|
| 1. Raw material extraction | Cradle | Mining, drilling, logging, farming | Habitat destruction, pollution, energy use, water use |
| 2. Processing and manufacturing | Gate | Refining, forming, assembling, finishing | Energy consumption, emissions, waste, water use |
| 3. Transport and distribution | — | Shipping materials and products to factories, warehouses, and shops | Fuel consumption, CO2 emissions, air pollution |
| 4. Use and maintenance | — | Consumer using the product; energy consumed; repairs; cleaning | Energy consumption (for powered products), water use, consumables |
| 5. End of life | Grave | Disposal, recycling, incineration, landfill, composting | Landfill space, methane emissions, energy for recycling, potential pollution |
| Approach | Definition | Goal |
|---|---|---|
| Cradle to grave | Tracks environmental impact from extraction to disposal | Minimise total impact across the full life cycle |
| Cradle to cradle | Tracks environmental impact from extraction to the point where materials re-enter the production cycle | Eliminate the concept of waste — all materials are recycled back into new products |
The cradle to cradle philosophy, developed by Michael Braungart and William McDonough, envisions a circular economy where products are designed so that every material can be recovered and reused indefinitely, mimicking natural ecosystems where there is no waste.
AQA Exam Tip: You may be asked to compare cradle to grave and cradle to cradle approaches. The key difference is that cradle to grave ends at disposal (linear economy), while cradle to cradle loops materials back into production (circular economy). Cradle to cradle is the more sustainable model.
A formal LCA follows the international standard ISO 14040/14044 and involves four phases:
| Phase | Purpose | What Is Done |
|---|---|---|
| 1. Goal and scope | Define what is being assessed and why | Identify the product, its function, and the boundaries of the assessment |
| 2. Inventory analysis | Quantify all inputs and outputs | List all materials, energy, water, emissions, and waste at each life cycle stage |
| 3. Impact assessment | Evaluate the environmental significance | Convert inventory data into impact categories (global warming, acidification, water depletion, etc.) |
| 4. Interpretation | Draw conclusions and make recommendations | Identify the life cycle stages with the greatest impact; suggest improvements |
| Impact Category | What It Measures | Unit |
|---|---|---|
| Global warming potential (GWP) | Greenhouse gas emissions | kg CO2 equivalent |
| Acidification | Acid rain potential from SO2 and NOx emissions | kg SO2 equivalent |
| Eutrophication | Nutrient pollution of waterways | kg PO4 equivalent |
| Ozone depletion | Damage to the ozone layer | kg CFC-11 equivalent |
| Water depletion | Freshwater consumption | Litres |
| Resource depletion | Use of non-renewable resources | kg antimony equivalent |
| Human toxicity | Toxic substances harmful to human health | kg 1,4-DCB equivalent |
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