Life-cycle assessments
A life-cycle assessmentA 'cradle-to-grave' analysis of the impact of a manufactured product on the environment. Also known as a life-cycle analysis. or LCA is a 鈥榗radle-to-grave鈥 analysis of the impact of a manufactured product on the environmentThe immediate surroundings in which people live, or the natural world such as the land, air or water.. There are many detailed stages but the main ones are:
- obtaining the raw materialBasic material that goods are made from such as crops, metals, wood and animal products such as wool and leather. needed
- manufacturing the product
- using and maintaining the product
- disposing of the product at the end of its useful life
The four main stages
At all stages, an LCA is likely to include information about the use of energyThe capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow., transport of materials, and the release of waste substances into the environment.
1. Raw materials
All the raw materials we need come from the Earth鈥檚 crustThe outer layer of the Earth on top of the mantle., atmosphereThe layers of gases that surround the Earth. The important gases in the atmosphere are nitrogen, oxygen and carbon dioxide. or oceans, or are due to living organismLiving entity, eg animals, plants or microorganisms.. Obtaining these materials has an impact on the environment, including:
- using up limited resourceA resource that is no longer being made or which is made extremely slowly, such as crude oil and metal ores. such as oreA rock containing enough quantities of a mineral for extraction to be possible. and crude oilMixture of hydrocarbons, mainly alkanes, formed over millions of years from the remains of ancient dead marine organisms.
- damaging habitatA place where plants, animals and microorganisms live. through quarryingThe removal of rocks from the land., miningWhen natural resources are extracted from the ground., or felling trees
2. Manufacture
The manufacture of products has an impact on the environment, including:
- using up land for factories
- the use of machines and people
3. Use
The impact of a product on the environment during its use depends on the type of product. For example, a wooden chair has very little impact, unless it needs cleaning or repair. On the other hand, a car will have a significant impact, because its use depends on burning fossil fuels which releases pollutants.
4. Disposal
The disposal of old products has an impact on the environment, including:
- using up land for landfill sitesPlaces where refuse is buried underground.
- whether any or all of the product can be recycledUsed materials that have been reprocessed to make new materials. or reused
Question
This table shows some data about the energy needed in the life-cycle of a pillowcase:
| Life-cycle stage | Life time energy use (%) |
| Raw materials | 10 |
| Manufacture | 15 |
| Use | 70 |
| Disposal | 5 |
| Life-cycle stage | Raw materials |
|---|---|
| Life time energy use (%) | 10 |
| Life-cycle stage | Manufacture |
|---|---|
| Life time energy use (%) | 15 |
| Life-cycle stage | Use |
|---|---|
| Life time energy use (%) | 70 |
| Life-cycle stage | Disposal |
|---|---|
| Life time energy use (%) | 5 |
Discuss the use of energy during the life-cycle of the pillowcase, and describe one way in which the energy use could be significantly reduced.
One quarter of the energy use is associated with making the pillowcase, and very little in disposing of it. The greatest use of energy happens when it is being used, probably because of washing, drying and ironing the pillowcase. Energy use could be reduced by drying it outside and without ironing it.