The people of San Francisco weren't going to settle for yet another concrete smog-factory.

It was 2012, and it was time for a new football stadium. Legendary Candlestick Park had been home to the 49ers for decades, but the stadium was over 50 years old and falling apart.

Replacing Candlestick — site of " The Catch" — in the hearts and minds of fans would be hard enough, but 49ers Project Executive Jack Hill, who would oversee design and construction of the new stadium, told me there was added pressure to build something that was good for the environment, too.

This Niners fan isn't interested in your jive-turkey new stadium. GIF from the NFL.

"It was important to our ownership, the York family, that we incorporate a lot of green features," he said. "Because of where we are in the country, a lot of the community is very ... environmentally active."

Translation: San Franciscans wanted a stadium they could be as proud of as they are of their team.

So Hill and the gang got to work, and what they came up with was nearly unprecedented in American professional sports venues.

Levi's Stadium was the first NFL stadium to open with LEED Gold certification, one of the top sustainability achievements.

Photo by Jim G/Flickr.

On July 17, 2014, after about two years of construction, Levi's Stadium officially opened its doors. From day one, it's had a stamp of approval from the U.S. Green Building Council, a nonprofit that champions buildings "that complement our environment and enhance our communities."

The structure became the first stadium to earn the elite Leadership in Energy and Environmental Design (LEED) Gold status, a certification based on a 69-point scorecard. The 49ers' new home currently meets 41 of the requirements...

...which is just a long-winded way of saying, "This stadium rocks."

How? Let us count the ways:

Photo by Travis Wise/Flickr.

• 1,186 solar panels that create about half a megawatt of energy each year — enough to power the stadium's 10 regularly scheduled home NFL games.
• Charging stations for electric vehicles. 'Nuff said.
• An incredible water reclamation system. Jack Hill told me, "About 85% of the water we use on site comes from a reclaimed water source, including for irrigation and all of our toilets. It's huge during drought season."
• A lush rooftop garden. Not only is it nice to look at — these low-water-usage plants sure beat the black tar most buildings use on the roof.

The rooftop garden gives fans a relaxing place to stroll and keeps the roof cool. Photo by Jim G/Flickr.

• Bicycle valet and lockers to encourage locals to bike to the stadium via a nearby bike path instead of driving.
• Proximity to public transit. Hill said about 10-15% of Levi's Stadium patrons arrive on mass transit, such as Caltrain, which is a big point of emphasis in getting LEED certified. (He also said they're still working out some of the kinks here that have caused backups leaving the stadium.)

Plus lots of other odds and ends, like using high-efficiency LED lights in over 40% of the stadium's fixtures, sourcing construction materials from sustainable wood forests, and the venue's robust recycling program.

But it's fair to ask: Is this real impact? Or is this greenwashing?

Jack Hill told me that LEED certification has been common for commercial buildings for a long time, but it's really just starting to gain traction in sports stadiums. And it looks like he's right.

But the trend sure is growing fast. And it's raising a lot of questions.

A massive wall of solar panels and wind turbines helps power the Philadelphia Eagles' Lincoln Financial Field, which received silver certification in 2013. GIF from NRG/YouTube.

In 2011, Apogee Stadium at the University of North Texas received LEED Platinum certification, its main claim to fame being three towering wind turbines that feed the stadium with renewable energy.

Wind turbines churn outside Apogee Stadium. GIF from O3 Energy Solutions/YouTube.

In 2008, D.C.'s Nationals Park became the first Major League Baseball stadium to receive the Silver certification. A few years later, AT&T Park in San Francisco made enough updates to earn the same honor.

And there are many more examples in both college and pro venues.

Nationals Park earned its Silver in 2008. Photo by Rudi Riet/Flickr.

But some have argued that things like solar panels and using recycled materials in construction are just a drop in the bucket when it comes to the massive amounts of energy and waste involved in hosting large-scale sporting events.

I'm honestly not sure you can ever make stadium sports a positive or even neutral thing for the environment. But as the demand grows for new stadiums filled to the brim with the latest technology and amenities, you have to applaud the people like Jack Hill who are working hard to reduce the overall impact.

And maybe, just maybe, their efforts will have an unseen effect on the fans. Jeff Koseff, a professor of civil and environmental engineering at Stanford University, told the Mercury News:

"When 68,000 people go to a stadium and see the 49ers trying to make a difference, there is evidence, I think, that they will start thinking about sustainability and the environment also."

If he's right, then the 49ers just struck gold.