As the famous frog once sang, “It’s not easy being green” and that’s especially true when it comes to sports stadiums. Bringing tens of thousands of humans together to converge for a single event has its inherent challenges when it comes to sustainability—from the traffic and waste generated to the energy and water needed to keep these stadiums functioning. But, increasingly, teams from different sports around the world are introducing eco-friendly practices as well as modifying their stadium’s infrastructure so they can do better by the environment.

Here’s a roundup of some of the best stadiums, when it comes to playing the green game.

NRG Stadium, Home of the Houston Texans

Earlier this month, NRG Stadium was the first NFL stadium to illuminate its field during a night game entirely with LED lights. These 65,000 Light Emitting Diodes (LEDs) use 60 percent less energy than the previous lighting system. Rumor has it that the SF 49ers also considered going for some LEDs to illuminate the playing field at Levi’s but decided against it because there were concerns the uniforms might look pink on broadcast video.