Bird's Nest (National Stadium)

　　The National Stadium ("Bird's Nest") is located in the southern part of the central area of the Beijing Olympic Park, with a construction area of 258,000 square meters and a land area of 204,000 square meters. It accommodates 91,000 spectator seats, including approximately 80,000 fixed seats. The National Stadium project is a top-grade sports facility, designed for a 100-year service life of the main structure. The main building is elliptical, 333 meters long from north to south and 296 meters wide from east to west, with a maximum height of 69 meters. Construction of the National Stadium began on December 24, 2003, and was completed on June 28, 2008.

　　The National Stadium is situated on a gradually ascending base platform, allowing spectators to access the stadium from the Olympic Park along the base platform. The north side of the base is a sunken warm-up area, connected to the main competition venue inside via athlete passageways. The complex ancillary parts of the National Stadium and post-event commercial spaces are arranged beneath the elevated ground, enabling more rational access for different groups of people while maintaining the clarity, purity, and integrity of the main structure’s appearance. The part of the stadium above the base consists of seven floors, housing spectator service facilities, media work areas, and VIP reception areas. The part below the base has three floors, containing a zero-level internal loop, parking lots, and numerous functional rooms. The bowl-shaped stands are divided into upper, middle, and lower levels, with private boxes and their seating areas set between the middle and lower stands.

　　During the [event period], the National Stadium served as the main venue, hosting the opening and closing ceremonies, track and field events, and the football finals. The spectacular opening and closing ceremonies complemented the grand and imposing structure of the Bird's Nest, dazzling audiences worldwide. Outstanding athletes such as Usain Bolt and Yelena Isinbayeva achieved record-breaking performances at the Bird's Nest.

　　The main body of the National Stadium is formed by a series of steel trusses woven around the bowl-shaped seating area, creating the "Bird's Nest" shape. Its spatial structure is innovative, with architecture and structure seamlessly integrated—unique, aesthetically pleasing, and highly impactful, fully showcasing the beauty of natural harmony.

　　The steel structure of the National Stadium is one of the largest-span sports buildings in the world. Its roof envelope structure consists of a steel frame covered with a double-layer membrane system: a transparent upper layer of ETFE membrane fixed between the upper chords of the steel structure, and a semi-transparent lower layer of PTFE acoustic ceiling fixed under the lower chords of the steel structure and along the inner ring sidewalls.

　　Advanced energy-saving designs and environmental measures were employed in the construction of the National Stadium, such as effective natural ventilation and daylighting, comprehensive rainwater recycling, utilization of renewable geothermal energy, and the application of solar photovoltaic power generation technology. Beneath the football pitch in the Bird's Nest are 312 geothermal heat pump system wells. These wells absorb heat stored in the soil through underground heat exchange pipes to provide heating for the Bird's Nest in winter, and absorb coolness stored in the soil to provide cooling in summer, saving a significant amount of electricity. The top of the Bird's Nest is equipped with a specialized rainwater collection system, and the collected rainwater is ultimately reused for landscaping, toilet flushing, firefighting, and even track cleaning. These numerous advanced green initiatives make the National Stadium a truly large-scale "green building."