There’s a perfect environment that needs to be captured in order for a NHL hockey game to come to life. The perfect base, drainage systems, type of water, temperatures and humidity all need to come together in the perfect balance to create a setting that can keep players safe, fans comfortable, and the ice hard.

It takes a lot of water. A lot of maintenance. A precise science. And of course, a lot of energy.

Nearly every professional sports stadium in the United States uses a great deal of energy in order to keep its facilities up and running. Concession stands, lighting, jumbo-trons and everything in between understandably makes stadiums/arenas major energy hogs. However, there’s one thing that makes hockey so different from other arenas in professional sports: ice.

Special accommodations need to be made in order to keep the ice at the right humidity and temperature level while still keeping spectators comfortable. It takes anywhere between 12,000 and 15,000 gallons of water to form an ice staking rink and between 8-10 layers of ice issued to create a safe and durable surface. Together, this can require more than 1,500,000 kWh a year.

However, what is even more impressive than the NHL?s ability to create these perfectly precise indoor hockey rinks is their ability to run these major operations during every game and still be one of the most energy efficient organizations in professional sports.

In 2015 the National Hockey League received the 2015 Green Power Leadership Award from the U.S. Environmental Protection Agency (EPA). Thanks to their partnership with Constellation, the organization has been able to introduce more energy efficient measures into NHL arenas, counterbalance greenhouse gases and offset carbon emissions.

Pretty impressive for an organization that competes with facilities such as Cowboys Stadium which reportedly uses more electricity in game (up to 10 megawatts) than the entire country of Liberia uses in a year.

The NHL is making great strides in its green energy efforts and has become one of the most efficient organizations in the world of sports and entertainment.

Here are ten of the most impressive ways that the NHL is changing the game on energy efficiency.

Number 1: The Constellation Partnership resulted in millions of kWhs of Green Energy

In the 2014-2015 season, Constellation provided more than 271 million kWh of green energy certificates to match the NHL games and events. This energy was generates from environmentally preferable renewable resources. In the current 2015-2016 season the league will be using wind projects from throughout the United States and biomass from Canada.

Number 2: Individual Arenas Are Adding New Technologies to Reduce Energy Costs

In 2015, Amalie Arena, home of the Tampa Bay Lightning took advantage of Heat Pipe Technology, or HPT, in a move that saved the arena over $600,000 in energy costs almost immediately.

Number 3: The NHL is Using New Energy Certificates for the Stanley Cup Playoffs

Starting in 2013, the NHL began using Green-e Energy Certified Renewable Energy Certificates for their annual Stanley Cup Playoff game. For the 2014 season Playoffs, the NHL used 12,850 megawatt hours of green energy to help offset their total energy use.

Number 4: NHL Stadiums are Implementing LED Lights to Cut Down on Energy Costs

At Cambria County War Memorial Arena in Johnstown, PA, the home of the Pittsburgh Penguins, new LED lights were installed throughout the facility, including new lighting above the ice surface that helped reduce glare and improve visibility for players. The move is expected to reduce electricity consumption by more than 25% by the end of the 2016 season.

The Nashville Predators replaced their lights with a new LED system in their home Bridgestone Arena to improve visibility, reduce energy costs and save on cooling after the former lights began to impact the above-ice temperatures. The upgrades are expected to yield up to 75% energy savings for the organization.

Number 5: The League Used 550,000 Metric Tons of Renewable Energy Certificates in 2015

During the 2014-2015 season, Constellation provide the league with 550,000 metric tons of Renewable Energy Certificates and carbon Offsets. This equals 2.3 million kBtu of energy per game, or as much energy as 50,182 homes use in an entire year.

Number 6: The NHL Performed an Energy Audit on Every Building in Their System

For the 2014-2015 season, the National Hockey League performed a complete energy audit on every building in their system. They also purchased enough renewable energy to offset all of the electricity used by every facility in their organization. According to the president of the Green Sports Alliances, Allen Hershkowitz, ?nothing like this has ever happened in professional sports.?

Number 7: The NHL Green Energy InitiativeWebsite

The NHL is so serious about their energy improvement efforts that they have launched their own site, separate from the Green Sports Alliance called NHL Green. Here hockey fans and energy conservationists alike can get updates on the league and their efforts to promote sustainability.

Number 8: The Minnesota Wild Are About to Have the First NHL Arena with LEED Certification

The Minnesota Wild NHL team are about to become the first existing NHL stadium to be LEED certified. New efforts include a solar photovoltaic array on the outside of the Xcel Energy Center?s parking garage and a thermal array of the roof of the RiverCenter. The team is also looking to offset its energy usage by purchasing wind energy from its parent company Xcel Energy.

Meanwhile, the Edmonton Oilers are looking to open the first new LEED Silver-certified arena in the league during the 2016-2017 season.

Number 9: The Montreal Canadiens? Bell Center Were the First Professional Sports Venue That Solely Uses LED

The NHL isn?t just making strides in improving their own energy efficient efforts, they have also set a precedent for the world of professional sports. Since 2013, the Bell Center, home of the Montreal Canadiens, has been the only major league sports venue in North America that uses LED lights to provide the sole source of illumination for the venue?s playing surface. Making the change saved the team an estimated $125,000 per year on electricity, parts and labor.

Number 10: The NHL is Now the 17th Largest User of Green Power in the United States

According to the EPA, the NHL is the 17th biggest consumer of green power in the United States, thanks to the organization?s efforts and their partnership with Constellation. Despite being one of the biggest energy consumers in the world thanks to the astronomical amount of power it requires to power a NHL game, the organization is working arena by arena to implement these new green energy sources into each facility.