Materials can have an impact on the environment in a range of different ways and at different times during their life cycles. For example, the extraction, transportation and manufacturing of raw material consumes energy and produces carbon. However, when a material is reused or recycled the wider environmental impact of the material is significantly reduced.
The UK construction industry uses more than 400 million tonnes of material every year, making it the nation’s largest consumer of natural resources.
The industry can reduce the impact of materials used in construction by using alternative recycled and secondary materials, as well as considering the lifecycle impacts of materials from extraction through to disposal. The Government’s Strategy for Sustainable Construction featured a section on materials, which focused on reducing the environmental impact of materials used in construction as well as targeting responsible sourcing of construction products.
Minimising Embodied Impacts
Embodied impacts of a material or product are assessed through a lifecycle assessment and are often categorised into five stages: mining/extraction, manufacture, construction, operation and maintenance, demolition. A holistic approach to embodied impacts should be used as for instance, transporting large quantities of heavy recycled materials over long distances may be more damaging than using locally sourced virgin materials. Useful guidance includes the ‘A guide to understanding the embodied impacts of construction’ document published by CPA.
Click here to read about UK-GBC's recent work on reducing embodied carbon in buildings.
Life Cycle Assessment (LCA)
LCA is a method to measure and evaluate the environmental impacts associated with a product, system or activity, by assessing the energy and materials used and released to the environment over the life cycle. There are a number of other environmental profiling methodologies, including the Inventory of Carbon and Energy. CEN is developing a standard, CEN TC350 to ensure methodologies for assessing the sustainability of buildings and construction products are harmonized.
Green Guide to Specification
The Green Guide to Specification is an accredited environmental rating scheme for buildings which examines the relative environmental impacts of the construction materials commonly used in different types of buildings.
Recycled and Secondary Materials
Recycled materials are products made from the waste materials generated during construction and demolition. Secondary materials are by-products of other industrial processes not previously used in construction. The WRAP Aggregates Programme, AggRegain, promotes the use of sustainable aggregates by reducing the demand for primary aggregates and encouraging greater use of recycled and secondary aggregates.
Environmental Product Declarations (EPDs)
EPDs communicate the environmental performance of a product or service using an objective, neutral, comparable, credible and accurate approach.
Responsible sourcing is an approach that considers the social, ethical and environmental aspects of a construction product from extraction and use to recycling/reuse and disposal. The BRE standard BES 6001 for Responsible Sourcing is a framework that assesses the responsible sourcing practices throughout the supply chain of construction products and allows manufacturers to prove their products have been responsibly sourced.
For information on the responsible sourcing of timber visit the CPET website. CPET recognises the Programme for the Endorsement of Forest Certification (PEFC) and the Forest Stewardship Council (FSC).
Responsible sourcing programmes and schemes also exist for aluminium, steel & stone products.
Healthy Materials – Volatile Organic Compounds (VOCs)
The use of healthy materials in construction promotes better indoor air quality for building occupants. Volatile organic compounds (VOCs) have high vapour pressures that when released into the air – especially indoors - can have harmful effects on human health. They are emitted by a wide range of products including building materials, furnishings, paints and cleaning products. Low and VOC-free products and materials have been developed by a number of manufacturers for use in place of traditional harsh chemical-based materials.
There is also gathering evidence and demand for buildings free from toxic chemicals with a broader definition of what is toxic for human health. The Living Building Challenge accreditation scheme has produced a Red List of materials which are not permitted on sites attempting materials accreditation which has been used by clients with more challenging briefs. E.g. Google.