Life Cycle Assessment
Get to grips with Life Cycle Assessment for GCSE Chemistry with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. A life cycle assessment weighs the environmental impact of a product at every stage, from raw materials to disposal.
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Topic overview
A life cycle assessment, or LCA, evaluates the environmental impact of a product across its whole life — from obtaining the raw materials to its final disposal.
Four stages are considered: extracting and processing raw materials, manufacturing and packaging, use and operation during its lifetime, and disposal at the end of its life, including transport and distribution at every stage.
Some values can be measured accurately, such as the use of water, resources and energy, and the production of waste. But the effects of some pollutants are harder to quantify, so judgements have to be made. This means LCAs are not purely objective, and they can be biased to support a preconceived conclusion in advertising.
Revision notes
The four stages
Extracting and processing raw materials. Manufacturing and packaging.
Use and operation during the product's lifetime. Disposal at the end of its life, including whether it can be recycled. Transport and distribution are included at every stage.
What can be measured
The use of water, resources and energy sources, and the production of some wastes, can be measured relatively accurately.
These give objective figures that allow products to be compared quantitatively.
Why LCAs are not fully objective
The effects of some pollutants are harder to quantify, so value judgements have to be made.
This means an LCA is not a purely objective process. Selective or abbreviated LCAs can be devised to support a preconceived conclusion, and these are sometimes used in advertising.
Key points
- An LCA assesses environmental impact across a whole life.
- It covers raw materials, manufacture, use and disposal.
- Transport is included at every stage.
- Water, resource and energy use can be measured.
- Some pollutant effects are hard to quantify.
- LCAs can be biased to support a conclusion.
Worked examples
Example 1
Name the four stages considered in a life cycle assessment. [4 marks]
Model answer
Extracting and processing the raw materials (1 mark). Manufacturing and packaging (1 mark). Use and operation during the product's lifetime (1 mark). Disposal at the end of its useful life (1 mark).
Example 2
Explain why a life cycle assessment is not a purely objective process. [2 marks]
Model answer
The effects of some pollutants are difficult to quantify accurately (1 mark), so value judgements have to be made about their impact (1 mark).
Example 3
Explain why LCAs used in advertising should be treated with caution. [2 marks]
Model answer
Selective or abbreviated life cycle assessments can be devised to support a preconceived conclusion (1 mark), so they may present only the information favourable to the product being advertised (1 mark).
Common mistakes
Considering only the use stage.
An LCA covers the whole life from raw materials to disposal.
Forgetting transport.
It is included at every stage and is often significant.
Saying LCAs are entirely objective.
Value judgements are needed where pollutant effects cannot be quantified.
Giving fewer than four stages.
All four are examinable and each usually carries a mark.
Exam tips
- Learn all four stages in order.
- Mention transport as part of every stage.
- Explain the subjectivity through unquantifiable pollutants.
- Note the risk of bias in advertising.
Key terms
- Life cycle assessment
- An evaluation of environmental impact across a product's whole life.
- Raw material
- The natural resource a product is made from.
- Objective
- Based on measurable fact rather than judgement.
- Preconceived conclusion
- A result decided in advance and then supported selectively.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.