Most climbers have fairly miserable memories of nights at the Refuge du Goûter. The last stop before the final climb to the summit of Mont Blanc on the main route, this 1960s building is outdated, uncomfortable and an environmental hazard. Hygiene problems recur, night temperatures are icy and the two outside toilets are inconvenient and a source of pollution, emptying waste directly on to the mountainside for the past 50 years.

A few hundred metres away a new hut awaits mountaineers: a four-storey, egg-shaped structure, 16 metres high, on the Arête du Goûter. Part of it juts out from the cliff, over a 1,500-metre drop. This all-wooden structure, clad in stainless steel, was commissioned by the French Alpine Club and designed by the Swiss architect Hervé Dessimoz. It aims to be exemplary in environmental terms, self-sufficient for energy and water, and able to withstand winds of up to 300kph (186mph). The hut, which took five years to design and three more to build, had been due to open on 30 August, but a technical problem in the cooling of the solar thermal system has delayed that until next year.

Building the refuge above 3,800 metres was a technical and human challenge. Work was only possible from spring to autumn, so the job was spread over three summers, and was often interrupted by the weather. Workers were selected for their endurance and experience of working roped to structures.The site, often battered by 70kph winds, had a special 18-metre telescopic crane which could fold up in five minutes. "Working conditions were very tough, with constant danger," says Thomas Büchi, who supervised the project.

The hut was put together like a kit. The structural elements, made with spruce, larch and white fir from nearby forests, were assembled in the valley, hoisted by helicopter and mounted on the spot using a special resin adhesive, to limit the need for nuts and bolts. To tie the building to the cliff and absorb the vertical load, but also the twisting effect of the wind, struts had to be sunk 14 metres into the rock.

One of the design challenges was to provide the hut with a self-sufficient water supply for cooking and washing. Its egg shape is part of the answer. "The building is pointed into the prevailing wind, causing turbulence, which makes the snow slide across the outer skin and accumulate on a 60 sq metre grid. Heat from solar panels melts the snow, which collects in huge tanks," says Dessimoz. It can operate for 16 days without fresh snow.

There are solar panels, generating heat and electricity on the front of the building and the cliff face. Only the kitchen will continue to use gas. If there is no sunlight, a backup generator, running on rapeseed oil, produces electricity.

Unlike its predecessor, the new hut boasts six environmentally friendly toilets. To reduce water consumption, the design team borrowed the vacuum-suction principle used in aircraft. A tiny sewage farm will process organic waste, outputting highly compacted sludge which can, if necessary, be heliported down to the valley for final disposal. Any water released into the mountain environment will be clean. With triple glazing and dual-flow ventilation, insulated by wood-fibre panels, the temperature indoors ranges from 18C to 22C. "What we're saying is that, if it's possible to build a self-sufficient, eco-friendly building at 3,835 metres, there's no excuse for not doing it at sea level," say Dessimoz and Büchi.

The alpine club dismisses criticism that it has produced a high-altitude hotel, but the architects undoubtedly took particular care with interior design, using white fir throughout. The bunks are fitted with flaps for a modicum of privacy. The old hut will be dismantled next year, leaving only a more recent extension to accommodate groups in winter. But will this be sufficient?

Every year about 17,000 climbers attempt to reach the summit of Europe's highest peak, taking the Couloir du Goûter route. In summer, sometimes as many as 300 climbers spend the night here, before making an early start on the final ascent. The old building was designed to sleep 100, but often lodged almost 150, with people sleeping on the tables and floor. Dozens of tents are pitched outside, and the waste they leave behind is piling up.

The strain on the natural environment, exacerbated by global warming, is beginning to show. On 21 August the local council at Saint Gervais Les Bains warned that warm weather had increased the risk of falling rocks and advised that climbs be postponed. Local guides promptly cancelled all engagements.

According to a study by the Fondation Petzl, published in July, most of the serious accidents on Mont Blanc occur on this route – it is known as the Couloir de la Mort (death gully). In the past 20 years, 77 fatalities have been recorded between the Tête Rousse and Goûter huts, mainly when climbers were crossing the gully. The week before the council's warning, the air temperature stayed above freezing point. "At present it's so warm, stones are falling even at night," said Jean-Marc Peillex, the leader of the council.

There is nothing new about the problem. Last summer about 1,000 climbers had to dodge falling rocks as they crossed the gully, according to the mountain police. "It is a real hazard but we cannot ban climbers from crossing the mountains. It must remain a place of freedom, but with everyone taking responsibility for their acts," Peillex adds.

The fragility of the "crust" on the Tête Rousse glacier, crossed by climbers en route to the summit, compounds the danger. "The safety perimeter has been extended, after the collapse of part of the cavity roof a few weeks ago, but some people pay no attention," Peillex says. Work was due to take place this month to pump water out of the pocket which has once again formed inside the glacier. With the recent hot weather, and the associated melting, about 10,000 cubic metres of water are thought to have accumulated.

• This article originally appeared in Le Monde