Life Cycle Assessment (LCA) — Cradle to Grave Analysis

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.

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What Is a Life Cycle Assessment?

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.

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The Stages of a Product's 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

Cradle to Grave vs Cradle to Cradle

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.

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How an LCA Is Conducted

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

What an LCA Measures

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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LCA in Practice: Comparing Two Products