Greening the game: The world's most sustainable stadiums
Sports stadiums and pitches often require vast amounts of energy, water and raw materials to maintain them, with little prior thought given to sustainability. But the vast amounts of money involved in professional sport lends itself to exciting innovations, and the stadiums are no different.
The Six Nations returned to our screens this weekend and the spotlight was on Cardiff, where Ireland blew their shot at the Triple Crown and the Grand Slam.
One overlooked storyline, however, was the venue itself. The Millennium Stadium is the first sports arena in Britain to be certifiably 'sustainable', having earned the BSI British Standard 8901 for Sustainable Management Systems for Events in 2011.
By the Stadium website's own admission, when construction started in 1994, "managing the overall environmental impact of an event was not high on the agenda." However, the operators have since installed an array of sustainable features including LED lighting, an under-pitch rainwater harvesting system and A-rated refrigeration systems.
The sustainability turn-around of the Millennium stadium inspired us at edie to take a look at five other stadiums around the world where the stadium operation is as green as the pitch.
1) Lincoln Financial Field - home of the NFL's Philadelphia Eagles
'The Linc', as its known in Philly, was the first professional stadium in the US capable of generating all of its electricity on-site. 11,000 solar panels and 14 wind turbines generate the power, although the tubines only account for 1% of total output, providing more of a 'visual symbol' according to team minority owner Weiss Lurie.
The stadium is also a zero-waste facility, while the overall green program is now 'cost neutral' according to the team.
2) World Games Stadium
This serpentine stadium in Kaohsiung, Taiwan, was built for the 2009 World Games. It was the first stadium in the world to provide all its own electricity using the power of the sun. The 8,844 solar panels will generate more than enough electricity to power the building's 3,300 lights and two giant television screens.
The panels can reportedly generate 1.14GWh of electricity per year, preventing 660 tons of carbon dioxide from being pumped into the atmosphere by traditional power stations every year.
3) Levi's Stadium - home of the NFL's San Francisco 49ers
Levi's Stadium - which opened its doors for the first time in 2014 - has been connected to the City of Santa Clara's recycled water system, a move which will effectively make the venue drought-proof. The water source will account for about 85% of total water use within the stadium.
Recycled water will be used for playing field irrigation, a 27,000 sq.ft green roof, flushing toilets and cooling tower make-up water.
Levi's Stadium is also proud of its local food sourcing - with 78% of suppliers of stadium food located within 150 miles of the stadium, and 85% located within California.
4) Estadio nacional - Brasilia
The Estadio Nacional was reconstructed for the 2014 World Cup, where it hosted the quarter-final matchup between Argentina and Belgium. It's rebuilding cost around £550m, making it the second most expensive football stadium ever, after Wembley.
It is also the first stadium in the world to gain the coveted LEED Platinum certification. Its rating is based upon 169,000ft² of rooftop solar panels, a pollution-neutralising rooftop membrane and the fact that 95% of the original demolished stadium was recycled for its construction.
5) Rectangle Stadium
This Melbourne stadium seats about 30,000 spectators and features a unique cantilever design, uses 50% less steel than a typical roof structure.
Completed in 2010, the architects installed a photovoltaic thin-film integration that will help power the stadium's LED lighting units. The dome will also feature a rainwater harvesting system, natural lighting and natural ventilation to lower the structure's dependence on grid electricity.
The rainwater rainwater collection system alone saves up to 500,000 gallons of water every year, with enough left over to provide four other venues in the precinct with water.