The Olympic treasures touching the earth lightly

The Lee Valley White Water Centre, home of London 2012's Olympic Canoe slalom in Broxbourne, typifies the Games' green agenda. Almost 40 per cent of its materials have recycled content.

Athens' experience of boarded-up venues convinced London's organisers they must avoid that fate and since we won host nation with the promise to deliver the greenest games ever, this elegant and efficient building - and many others like it - exemplifies the true legacy of the 2012 Games.

What really mattered was building less and ensuring that what was built touched the earth lightly. It was a clear case of less is more, much of which will be unseen by the general public. For example, the world's press and broadcasters will arrive at the Media Centre through an extraordinary bridge enclosed by a timber screen of unfinished larch and a ceiling of stressed-skin plywood panels.

Each of the five new permanent sporting venues in the Olympic Park - the stadium, aquatics centre, velodrome and two community sports facilities - has been designed with efficiency in mind. The velodrome is a particular showcase for sustainability and clever architecture. Underfloor heating of the track keeps the cyclists' zone at the carefully controlled temperatures required for shaving seconds off their times, while jet nozzles in the balconies boost heating and ventilation in spectator seating areas.

Better still, existing venues - from Wimbledon to the ExCel Centre - have been put to work. ExCel alone will house five temporary stands and more than a dozen sporting events.

In another Olympic first, binding targets were written into planning agreements. Without targets, it's impossible to measure success. Hopkins Architects' velodrome exceeds the energy efficiency targets by more than 30 per cent, and the stadium used less than a quarter of the steel of Beijing's Bird's Nest.

It's not just the buildings but also the new open spaces that will be pushing the boundaries of sustainable design. After the Olympic train moves on, east London will be home to the Queen Elizabeth Olympic Park - its 102 hectares of metropolitan open space only slightly fewer than Kensington Gardens.

A new approach, which owes as much to ecology as aesthetics, relies on spreadsheets - not planting plans - to determine which plant species should be located within each square metre of new parkland. Under the direction of James Hitchmough, professor of horticultural ecology at the University of Sheffield, 85,000 sq m of the northern park have been seeded rather than planted. This makes planting more affordable, but the end result is subject to the vagaries of climatic variation - wind, rainfall and temperature.

"Sustainability does not happen by itself," Dan Epstein, the Olympic Delivery Authority's former head of sustainability, reiterated at a conference recently. It requires vision, leadership, technical expertise and constant monitoring. It's also invisible. Visitors to the Olympic Park will not be greeted by a wind turbine or photovoltaic arrays.

But the game's not over yet. Locog's staging of the Games will be critical to promoting the sustainable agenda in the public eye. And the Olympic Park Legacy Company (soon to be transformed into a Mayoral Commission), responsible for what happens next, will be the ultimate rainmaker for east London.

London 2012 Sustainable Design - Delivering a Games Legacy, by Hattie Hartman, is published by John Wiley & Sons this week.