BBVA Stadium also transformed daily practices such as waste management. The challenge was not only to separate waste, but also to ensure that all suppliers for everything from food to cleaning products operate under sustainable criteria. Club de Futbol Monterrey began incorporating environmental conditions into its vendor contracts, from recyclable packaging to reusable or compostable products.

“We even ask them for documents indicating the final destination of waste,” says Molina.

The stadium has eliminated around 90 percent of its PET plastic during matches, through soft drink dispensing machines and the use of reusable cups. As for water, it increased the number of meters from 6 to 20, and fine-tuned irrigation with predictive analysis to define when and how much to irrigate.

That efficiency is helpful, but large volumes of water are still required. The official regulations of this year’s World Cup require that the matches be played on natural grass, as it is considered to offer better conditions for player performance. And the watering is done with potable water rather than treated water.

Ever since the 2014 World Cup in Brazil, FIFA has had guidelines for stadiums’ environmental efficiency, such as the responsible use of water, but some of its own requirements are not always consistent with the sustainability goals the organization promotes.

“Before, irrigation was done with reclaimed water; today, potable water has to be used to take care of the grass,” Rocha explains. Potable water is both more expensive and of limited availability in a city notorious for water shortages.

Artificial turf fields also require water for purposes like temperature control, using about 900 liters (238 gallons) per day. But natural grass needs roughly 50 times more, requiring irrigation of up to 50,000 liters (13,209 gallons) per day. In comparison, the average daily water consumption per person in Mexico is 150 liters (40 gallons), which means the pitch uses the daily water supply of 333 people.

Certifying the operation of the BBVA Stadium was not just a matter of complying with indicators, but of transforming operational habits in a city with complex environmental conditions. Ensuring environmental quality in Monterrey, with high levels of pollution and extreme temperatures, was a major task.

The indoor environment is one of the certification criteria. Although the stadium is open for the most part, it had to offer healthy conditions in enclosed areas such as offices, dressing rooms, and VIP areas.

“One of the most important challenges was environmental quality, but also comfort: that people were comfortable, in terms of their health, temperature, and even psychologically,” Rocha says. To achieve this, ventilation systems were implemented with special filters, pollutant sensors, and turbines that improve the air flow in the stands. The stadium invested more than 1 million pesos (about $57,400) in the carbon dioxide extraction system.

BBVA also went through a cultural shift as part of the certification process. Coordinating more than a thousand suppliers, raising staff awareness, and changing daily habits is work that continues long after certification.

Interior of the Mexico City Stadium, formerly the Azteca Stadium.

Photograph: Hector Vivas/Getty Images