Life cycle assessment

LCA takes into account the whole life cycle of the product and, as such, it is also referred to a 'cradle to grave' assessment or 'eco-balancing'. As we attempt to ‘close the loop’ – to make production/consumption systems more sustainable (see sustainable development), the life cycle approach is also increasingly referred to as ‘cradle to cradle’. This is because the system under study may incorporate re-use and recovery/recycling stages, thus postponing if not avoiding the ‘grave’.

LCA is used to identify environmental inputs and outputs, and evaluate their impacts throughout the life cycle.

Here are some examples of inputs and outputs for a product, e.g. a washing machine:

and for a manufacturing plant/ facility:

(See Input/output diagrams in emissions overview.)

LCA integrates measurements over the whole life cycle to help ensure that improved environmental performance at one stage is not achieved at the expense of worse performance at another stage. It can also be used to make comparative environmental assessments between two or more products (or services, facilities, etc.), that provide the same function.

If the lifetime of a product can be extended, then the environmental cost of manufacturing and disposing of an equivalent product is deferred.

For example, consider extending the life of an item of process equipment, such as a heat treatment oven. Reduction in environmental cost may be possible during the stages of the oven’s life cycle (raw material extraction, manufacture, distribution, use, disposal).

Consideration would have to be given to the oven’s performance in the ‘use’ phase. For example, would the ‘long life’ item also be more economical in its use of fuel in the use phase?

A ‘long life’ oven might use more resources during manufacture, as it will need more durable components. Also, any new improvements in design and performance which occur in the first half of the implement’s life, (which might be incorporated in a replacement item) will not be available until the extended life comes to an end.

This route is especially unattractive in markets where innovation and the rate of technological improvements are rapid. For example, consider mobile telephones. Here replacement is governed by customers wanting improved performance and functionality, not by products wearing out.

Minimise hazardous content

Many products contain significant quantities of materials which, although they do not pose a risk to users, may be damaging to the environment when the product is disposed of, e.g. batteries containing cadmium or mercury.

Manufacturers and importers of products are now obliged by law to minimise the hazardous content of some types of material.

Design for repair

In many cases, trends in design have made it less likely that products will be repaired and more likely that they will be disposed of in the event of failure of a part. Products are not designed to be repaired and repairs are uneconomical. This is true of much electrical and electronic equipment. The unit cost of production has decreased dramatically in real terms in recent years. The pace of technological change has also increased and equipment becomes obsolete very quickly. Products which were a high cost purchase a few years ago may now be regarded as being uneconomic to repair.

For example, in the past video recording machines were a high value purchase which were taken for repair when critical components failed. It has, arguably, became more cost effective to dispose of a faulty unit and purchase a new one. Also, operational VHS video recorders are being disposed of because the technology is obsolete and more advanced alternatives such as DVD are now available.

The rapid introduction of new electronic devices also means that the quantity of waste requiring disposal is larger. Regulations regarding Waste Electrical and Electronic Equipment are intended to help manage this situation.

Design for dismantling

The trend for more disposable items is unlikely to be reversed. One measure which will at least allow discarded items to be dealt with using means which are higher in the waste hierarchy is design for dismantling (or design for disassembly).

Here, dismantling of a product at the end of its useful life, so as to provide separate materials for recycling, is considered at the design stage. Some measures which may make dismantling less labour-intensive are:

• labelling different plastics using the internationally recognised numbering system and recycling symbol (symbol to be placed in prominent positions on all components, visible prior to disassembly where possible);
• use fastenings which can be undone with minimum labour, e.g. screw not rivets;
• use fastenings which spontaneously release at set temperatures (as used in some designs of mobile telephone); and
• avoid using mixed materials if possible, e.g. use all-aluminium cans instead of aluminium lid with steel body . This avoids the need for shredding and magnetic separation of the different metals prior to re-melting.