It's been billed as the "Green Olympics," but do the showpiece venues that will host the Games' key events live up to the theme?
The record is mixed, experts say, with the best venues for the Beijing Games setting a standard for energy-efficient building while others betray the promise of environmental sustainability.
In the end, much was left to the developers, with few mandatory guidelines set by Olympic organizers, meaning they had little leverage to impose consistent standards.
"The intention is always positive, but if you don't give people some mandatory parameters on which they have to work, then you allow them to make shortcuts," said Theodore Oben, head of the sport and environment programme at the United Nations Environment Programme.
"A lot of the building and facilities are developed by contractors . If the parameters are not mandatory, then the contractors will have either to do as much as you want or more, or they may make shortcuts if they want to save money," he said.
The National Stadium, known as the "Bird's Nest" for its latticework of interwoven steel, and the National Aquatics Centre, or "Water Cube," the rectangular swimming venue that sits by its side, are considered among the world's most architecturally adventurous new buildings.
But are they the most green?
NEST OF STEEL
"It's an iconic structure, but a green building it ain't," Robert Watson, CEO of green building consultancy EcoTech International, said of the Bird's Nest.
The stadium features non-flush toilets equipped with sewage treatment systems, a rooftop photovoltaic system with a capacity to generate 130 kilowatts of power, and facilities to collect 58,000 cubic meters of rainwater annually.
But to Watson the structure itself, which used some 42,000 tonnes of steel, is the problem.
"The fact that it uses 10 times the materials of a normal stadium, any green virtue is inundated by that," he said.
"Ninety percent of the structure does nothing but hold itself up," said Watson, who founded the Leadership in Energy and Environmental Design (LEED) rating system for green buildings.
Experts say the Water Cube fared better.
