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Sustaining the challenge Just how serious are we about sustainable development? Peter Guthrie argues that construction should be leading the way.

The words sustainable development contradict each other. The phrase itself - though possessing a nice ring when delivered at Rio - can best be described as triumph of hope over experience. Development, based on economic growth with its current reliance on fossil fuel-derived energy, is not sustainable, and anything that helps us believe it might be will in time cause grave harm.

The reality is that we are the first generation to wittingly damage our global environment in the pursuit of economic growth. Pollution and depletion of resources are happening now on a global scale despite vast areas of the world still being 'underdeveloped' - the economies of China and India have really only just begun to grow.

And expressions to hide behind are not what is needed to turn the situation around. Rather, people who can make a difference should be preparing the way for solutions which are real, solutions which really address matters such as renewable energy, tolerable growth and environmental sustainability.

The reality is that such solutions - if found at all - will only be found in the long term, perhaps over the next 50 years. But in the short term much can be done to eke out those resources that we still possess and to maintain economic growth in the least environmentally harmful way. In short to improve the sustainability of our development.

Engineers are in the forefront of this survival race. In fact, the minimisation of waste in construction serves as a neat proxy for what could happen globally and can be taken as an example of an approach to development generally.

For a new building to be built in a resource-conscious world, there should be a demonstrable and pressing need. The need would be subject to stringent examination, accompanied by a search for alternatives.

The building's location is critical. Should it be positioned somewhere near existing transport systems? If not would the building serve as a generator of more private car traffic and add to unmanageable congestion and pollution?

Then how is the building going to be designed? Should it meet the client's criteria, if these lead to a less than efficient use of materials? A requirement for a low weight structure with a 20 year life span, for example, might better be replaced with a shell of higher capital cost but with a life of 100 years and inherent flexibility. But extending the life of the structure leads to the question of how buildings will be used in the future.

So the logic goes on. The design of what is to be built has to be conducted with all resource implications fully understood. The designer should work with standard lengths, widths, depths in mind. Standard windows, doors, trusses, beams, columns and planks of wood could be specified with the intention of preventing off-cuts.

And which materials best lend themselves to practical construction on site and what practices result in the most efficient use of those materials? The use of composite materials, for example, which may then be inseparable at demolition, rendering the components useless, must be avoided.

However, while a flexible design coupled with suitable, durable materials is important, maintainability is vital to keep the building in useful commission as long as possible. And finally, when a building really has come to the end of its useful life, with demolition the only option, thought should be given to re-using the materials that arise.

In short we should start from the premise that all building and built infrastructure is material on its way to the tip. The great challenge for engineers and planners is to prolong the period over which this material is useful.

Much needs to be done to educate designers and builders - and the clients they work for - in waste minimisation. New legislation and incentives to encourage changes in attitude is needed, plus the publicising of new standards by which the appropriateness of reclaimed materials could be judged.

It is worth noting that of the 400Mt to 500Mt of construction materials used every year in the UK, the majority is aggregate and concrete based. Aggregate is a high volume and low cost material, the only cost associated with it being the cost of winning and transporting it. But there is no acknowledgement of its finite nature, in practical terms, and no payment made for the reduction of the environmental and resource capital.

The absence of a primary aggregate tax works against efficient use of materials and against any serious use of secondary or recycled materials for aggregate. This is compounded by lack of real tax incentive to make use of recycled materials. Of the 24Mt of 'hard' waste from Britain's construction industry each year, less than 5% is recovered for beneficial re-use.

Minimising waste in construction is one way to illustrate what might be done generally to maximise the world's resources and best sustain development. And it is worth asking what can be done to improve the sustainability rating of civil engineering? A great deal, is the answer.

The environmental debate has been held and the environmental movement has won acceptance for movement towards sustainability and environmental protection. Now the challenge is to find the solutions. Engineers, along with scientists and politicians stand centre stage in the search for a way forward that meets today's demands while protecting the rights of future generations.

There is real room for hope. Young graduate civil engineers are entering the profession much more environmentally aware and with different attitudes and approaches. Along with their young colleagues around the world, they will hold much of the responsibility for achieving development which is truly sustainable in environmental terms.

Peter Guthrie is environmental director of Scott Wilson and leader of the team that produced the CIRIA report Waste minimisation in construction.

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