ENVIRONMENTAL IMPACT OF CONSTRUCTION
From material extraction, processing, component assembly, transport and construction, to maintenance and disposal, construction products have an environmental impact over their entire life cycle.
- 10% of the UK CO2 emissions arise from the production and use of building materials.
- Each year the UK construction industry uses 6 tonnes of building materials per head of population.
- Materials production and construction accounts for an estimated 122 million tonnes of waste, or 30% of the total arising in the UK.
LIFE CYCLE ASSESSMENT (LCA)
A method to measure and evaluate the environmental impacts associated with a product system or activity, by describing and assessing the energy and materials used and released to the environment over the life cycle. The term life cycle analysis is also sometimes used to describe the same process.
ENVIRONMENTAL IMPACT ASSESSMENT
The process of interpreting the effect that removals or releases to the environment will have on particular environmental systems. There is no absolute "end point" at which an impact has to be measured-e.g. burning coal will cause "fossil fuel depletion", "global warming potential" and even "risk of drought"-but common endpoints and measurement techniques may be agreed which allow the impacts of different activities to be compared.
ENVIRONMENTAL PROFILES OF CONSTRUCTION MATERIALS, COMPONENTS AND BUILDINGS www.bre.co.uk/envprofiles
Life Cycle Assessment (LCA) is an internationally established approach for analysing the environmental impacts of products and processes. BRE have devised a method in partnership with DETR and 24 Trade Associations from the Construction Products sector which provides a single approach for applying LCA to all types of construction products.
Environmental Profiles provide independent, "level playing field" information about the relative environmental impacts of different design options, enabling architects, specifiers and clients to make informed decisions about construction materials and components.
A range of Environmental Profiles are already available on the UK Database of Environmental Profiles of Construction Materials and Components, accessed via subscription at our website. Trade Associations and materials producers can work with BRE to add new Profiles at any time. Materials manufacturers can obtain Certified Environmental Profiles through BRE Certification Ltd.
Comparisons between Environmental Profiles are always informative, but do not necessarily allow the reader to reach a precise conclusion. For example, which gives less overall environmental impact: a product with high global warming impact but low water pollution impact or a product with low global warming impact but causing significant water pollution?
BRE undertook a consensus based research programme to weight the issues covered by LCA from the perspective of seven UK construction interest groups, including the public sector, construction materials producers and manufacturers, property professionals, environmentalists and academics.
The results showed a surprising degree of consensus about the relative importance of different environmental issues across a broad range of interest groups. This consensus has been used to produce a set of weights to convert Environmental Profiles data into a single score reflecting environmental impact in the UK. The data in the thirteen impact categories are multiplied by the agreed weight for each category and combined to produce an Ecopoint score.
To aid interpretation, Ecopoints are derived so that the annual environmental impact caused by a typical UK citizen creates 100 Ecopoints. More Ecopoints indicate higher environmental impact.
WHOLE LIFE COSTING AND ENVIRONMENTAL IMPACT
WLC and LCA in the construction industry have developed separately in response to economic and environmental issues but the two tools have much in common, as shown in figure 1.
The key similarity is that both utilise data on:
- quantities of materials used,
- the service life the materials could or will be used for
- the maintenance and operational implications of using the products
- end of life proportions to recycling (and sale value) and disposal
The key differences are:
- conventional whole life costs methods do not consider the process of making a product, they are concerned with the market cost. Life cycle assessment considers production.
- WLC is usually discounted to present value over time, environmental impacts are not.
Figure 1: Commonality within the Building Cycle of issues relating to WLC and LCA
|Stages in the Building Life Cycle
||1. Extraction of raw materials
|2. Production of building components