Recycled aggregates play key role in construction

Measures to promote sustainable construction range from the drawing board, where architects and engineers increasingly specify energy saving windows and heating and ventilating systems, adopting solar power and water recycling where possible, to the large scale recycling of construction and demolition waste which replaces virgin aggregates, the mining of which raises key environmental issues. LAWE Editor Alexander Catto reports on recent developments in these fields.

On the building facilities front the Environment Agency is practising what it preaches by adopting solar power in its own buildings.

Hot water in the kitchen and toilets of the Agency's Isca building in Exeter will in future be provided by newly installed solar panels. They have been fitted on the south-facing roof of the building, which is situated on Exeter's Sowton Industrial Estate.

The installation cost £6,750 and was commissioned at the end of January this year. The financial payback of the system is likely to be achieved over a 25-year period. "We hope the panels will virtually replace the 9kW electric immersion heater which has previously supplied hot water to the building," said Alan Hale, Environment Agency Facilities Team Leader.

"It must be realised however, that the real value if such a system lies in the reduction of CO2 emissions. It clearly demonstrates our environmental credentials and commitment to a sustainable environment that seeks to protect our natural resources for the long-term good rather than the short-term gain." Mr Hale added, "It is important that the Environment Agency practises what it preaches."

Heathrow Terminal 5 'recycled'

On a larger scale, and underlining the great strides that are being made in using recycled building materials, London Remade, the organisation behind the Mayor of London's Green Procurement Code, reports that buying building and construction materials made from recycled products is proving a popular choice.

A recent survey of London businesses found that, out of the recorded £21,232,000 spent on recycled products, 45% was on building and construction materials. More than 80 London companies signed up to the Mayor's Green Procurement Code took part in the survey. Collectively, their commitment to buy a range of recycled products has diverted over 375,000 tonnes of waste from landfill.

One example of a company that re-uses concrete and other construction waste for development projects is BAA. It is using large amounts of recycled construction material to build Terminal 5 at Heathrow Airport. Suzanne Worrall, Sustainability Manager from BAA, said: "We are now recycling over 82.5% of our airport construction waste and our surplus is so great we have begun selling our recycled concrete to other companies. Recycling construction waste is bringing BAA clear business and environmental benefits."

Other recycled products purchased by London businesses included; paper, which accounted for 20% of the spend, roads and pavements (14.3%), stationery (9.8%), bins, bags and containers (2.6%), manufacturing (2.8%), packaging and storage (1.6%), parks gardens and landscaping (0.7%), street furniture (0.5%), medical/hygiene (0.5%) and water/drainage (0.1%).

Other organisations playing key roles in the drive to replace virgin aggregates with recycled alternatives include BRE, TRL and WRAP.

Also active in this field is CIRIA, the construction industry research body, which says that the demand from coastal and river engineering for primary aggregate is increasing and is expected to expand further with the growing need for coastal and river protection works. It is recognised that this demand will need to be met, in part, by alternatively sourced aggregate. The Environment Agency target states that 20% of aggregates used should be from secondary sources.

CIRIA's recently published Potential use of alternatives to primary aggregates in coastal and river engineering (C590)* offers guidance aimed at reducing the impact of river and coastal engineering by promoting the use of alternative materials in place of primary aggregates. It provides more sustainable and cost effective solutions for river and coastal engineering, lists the available materials, assesses their suitability for use in the surrounding environment and identifies the technical and processing barriers to their use. It also contains case studies and makes recommendations for future research to enhance the use of alternative aggregates.

CIRIA is a member-owned organisation that works with the constructio industry, government and academia to provide performance improvement products and services in the construction and related industries.

Aggregates levy criticised

The road towards sustainable construction is not without its problems, with the Quarry Products Association (QPA) calling for an urgent rethink of the aggregates levy in the run-up to the Budget. The association, which represents over 90% of the UK's quarrying industry, has highlighted continuing environmental inefficiencies and costs associated with the aggregates levy in representations to the Treasury. The QPA's Chief Executive, Simon van der Byl, said: "The aggregates levy is nominally an environmental tax. According to the Treasury's own rules, environmental taxes are supposed to 'deliver real environmental gains cost effectively'. In practice, however, the Treasury has so far failed to demonstrate that the levy has any net environmental benefits."

The QPA has identified key environmental and economic problems and uncertainties associated with the levy. These include:

The levy is a sales tax and not a tax based on environmental impacts, which therefore provides no incentive for operators to further improve environmental performance. Due to a range of regulatory and voluntary factors, the environmental performance of the aggregates industry has continued to improve since the tax rate of £1.60 per tonne was calculated in 1999.

The levy rate is supposed to reflect the environmental cost of extraction, but has not changed in response to reducing environmental impacts. The calculation of the levy rate, for example, perversely assumes that quarry restoration for wildlife habitats and public amenity provides no environmental benefits. Simon van der Byl concluded: " The aggregates levy is a mess."

*Potential use of alternatives to primary aggregates in coastal and river engineering (C590) is priced at £40 to CIRIA Core and New Books Club members and £80 to others. To buy a copy, visit tp://www.ciriabooks.com or contact CIRIA, Classic House, 174-180 Old Street, London EC1V 9BP. (T) 020 7549 3300; (F) 020 7253 0523; (E) enquiries@ciria.org

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