The all-powerful

Marks explains that the statue is, in fact, a scale model of a much, much larger version to be built in northern India, a project on which London-based Fulcrum is environmental consultant. "The Maitreya Buddha will be the world's tallest monument," says Marks. "At over 500 feet, it will be three times the height of the Statue of Liberty."

The statue is a competition-winning design from British architect Whinney Mackay Lewis. Mott MacDonald, the project's structural engineer, is also UK-based. Their client is Buddhist organisation the Foundation for the Preservation of the Mahayana Tradition.

It is not just the monument's physical size that makes it unique. The scope of the project is impressive, too: the giant Buddha is being designed to last for 1000 years. The huge structure must withstand high winds, extreme temperature changes, seasonal rains, environmental pollution and possible earthquakes and floods during this time.

If that weren't enough, Marks must also make this remarkable project sustainable. Sitting in his cluttered office, surrounded by jumbled heaps of paper and rolls of drawings, he explains: "The client wants a model of responsible development that is environmentally sustainable." It is a task Marks seems to be relishing. Already, he has set the project team a difficult target: "The monument will have the same environmental impact as the paddy field on which it will be constructed," he states. This means it will emit the same amount of carbon dioxide and methane in a year as the field does.

The huge monument will be erected at Bodhgaya in the state of Bihar, at the site where, according to Buddhist scriptures, the historical Buddha, Siddhartha, found enlightenment some 2500 years earlier, and where the fifth Buddha, Maitreya, is expected to appear and demonstrate his own enlightenment. "He's due any day now," says Marks. "That is why the design period is so short and the construction programme is fast-track." Enabling works are already under way and the statue is due for completion in 2005 (see construction programme, page 39).

Everything about the project is enormous, from its £100m price tag to the statue's supporting structure. The towering, bronze-clad Buddha is mounted on a 17-storey throne that is itself a major public building. Pilgrims will enter the throne through the giant lotus cushion supporting the Buddha's feet. After passing through several smaller rooms, they will arrive at the cavernous main auditorium, which has a wall containing 100 000 small Buddhas. From here, lifts will convey visitors heavenwards to a large prayer hall occupying the throne's upper floors, and to a rooftop garden terrace. Another bank of lifts will then whisk pilgrims still higher to shrine rooms contained in the statue's torso and head.

Around the foot of the statue is a four-storey halo of accommodation, dubbed "a living wall" by Whinney Mackay Lewis director Graeme Rapley. This will comprise a ring of linked accommodation as well as a monastery, a nunnery and rooms for functions ancillary to the statue and throne building.

The wall will serve two additional functions: it will provide a security cordon against the outside world, while within its confines it will create an enclosed area of landscaped gardens for quiet meditation. "The living wall is a modern equivalent to a castle wall," explains Marks. "It is designed to withstand an attack from 200 armed raiders." And, because of the monument's location on the same flood plain as Bangladesh and uncertainty over the impact of global warming, the wall will double as a flood defence.

For Marks, the wall will also define the boundary within which the complex will have to be self-sufficient in water, power and waste. This is partly to satisfy the client's sustainability agenda, and, more conjecturally, to safeguard the statue against any future breakdown of society during its millennium lifespan. "One of the main parameters in designing the monument for a 1000-year life is what is going to happen to Bangladesh – if the country floods, the inhabitants have to go somewhere," he says.

The key issue for the temple is water. Although a surplus of water leading to flooding is one concern, by far the biggest problem is a shortage of water during the dry season. In this part of India, the monsoon rains are the primary source of water, which the local rice farmers supplement by water drawn from wells. If the temple were to begin siphoning a large quantity of water through new boreholes, this could, potentially, have a catastrophic effect on the local inhabitants. Marks gravely explains that the project team's biggest concern was that "our next-door neighbours would die if we took their water".

His solution involves gathering as much water as possible during the monsoon and hoarding it in huge underground storage tanks for use during the eight months of the year when no rain falls. The tanks will be incorporated into the foundations of the living wall and have the capacity to hold up to 35 000 m3 of rainwater, enough for the structure's needs for the rest of the year. Rainwater will be collected from the roof of the accommodation blocks rather than by the statue itself for fear of contamination from the monument's bronze "skin". As back-up, two boreholes have been sunk to top up the tanks should supplies run low.

One area Marks is investigating in an attempt to minimise water consumption is the drainage system. At its peak, the visiting population is expected to top 10 000 pilgrims a day – a substantial number given that all waste will have to be treated on site. Two schemes are under consideration: a conventional wet system using flushing toilets, and the more radical solution of composting. Marks favours the latter because "it would keep human waste in one spot and so reduce the opportunity for disease to spread". According to Marks, after about a year, the compost forms a benign product that could be used as a fertiliser by local farmers. The composting solution would also eliminate the need for long pipe runs and associated maintenance over the project's life, and reduce the demand on his precious store of water. He has still to convince the client of his argument, however.

Food waste will also be treated on site. It will be fed into a digester – a large tank containing bacteria that will break down the waste into a series of by-products: sludge, liquid and methane gas. The sludge will be used as fertiliser, while the methane will be piped to a generator where it will be burned to provide electricity. The liquid waste needs to be further treated, and so will be passed through a reed bed – a series of ponds containing plants that digest any nutrients left in the liquid – to help clean it. The well-fed plants are then cropped and fed back into the digester to continue the process.

While the methane will generate some electrical power, most of the site's needs will be met by 7000 m2 of photovoltaic panels, which will form the roof of the living wall. Funding for these will come, in part, from the Indian government. After 25 years, when the generating efficiency of the panels decreases, newer, more efficient units will replace them. The old units will then be donated to the local community as a free source of electricity.

To keep the monument's power load to a minimum, Fulcrum is attempting to make the fullest use of daylight to illuminate the throne's interior. Studies using the "artificial sky" model are under way at the Bartlett School of Architecture on how to achieve the delicate balance between maximum daylight, heat gain from the sun and providing the right light levels to give the interiors a mystic ambience.

Keeping the inside areas comfortable without resorting to a power-guzzling air-conditioning system is proving a challenge. One major problem the project team has faced has been that of trying to forecast what the world and its climate will be like 1000 years from now. The intensity of the monsoon season is expected to increase, for example, and summer temperatures in Bodhgaya are predicted to rise from their current peak of 45°C to a maximum of 50°C as global warming starts to take effect.

During the hot dry months, the conditions inside the auditorium will be kept at a comfortable level by supplying cooled air to the space through a series of floor voids. The air will be cooled (without the use of air-conditioning) by drawing it through two giant pipes – which Marks calls "earthpipes" – buried in the ground beneath the living wall. In this part of India, the ground has a constant temperature of about 25°C. The pipes work by drawing heat from the ground in winter when air temperatures approach freezing, or by storing heat in the ground in summer.

The ventilation design uses the statue as a giant chimney: air will rise up inside the body of the Buddha and leave through vents in the top of the figure's head. As the air rises, it will draw air, cooled by its journey along the earthpipes, into the monument's interior.

"I have the biggest chimney in the known universe and the biggest displacement ventilation system on the planet," laughs Marks. "It can't really go wrong." He is also looking at installing wind generators in the neck of the statue to supplement the temple's generating capacity and to help ensure the site's self-sufficiency.

The statue's massive earthquake-resistant structure has also been designed to be sustainable. The scheme by Mott MacDonald allows for sections of the structure to be replaced over the statue's long life.

The client wants the Maitreya Buddha to benefit the local economy and so help meet the criteria for social and economic sustainability. To that end, when construction of the statue starts in early 2002, the project team is planning to build a new foundry locally to supply the figure's bronze cladding.

In addition, the throne will be constructed from local stone, which will be carved on site using local labour. "Bihar is possibly the most criminal bit of the globe," says Marks. "It is an area in need of regeneration."

Work is scheduled to begin on the statue's foundations later this year. If all goes as planned, the project will be completed in five years' time – and Marks will have to find a replacement for the resident in his reception.