New Volkswagen Passats are seen behind the Chattanooga assembly plant's building front.

Volkswagen's Chattanooga assembly plant was cited for its sustainability efforts as the German automaker won the World Environmental Center's 30th anniversary Gold Metal Award.

The plant, the only automotive factory in the world to have earned platinum Leadership in Energy and Environmental Design certification, conserves 720,000 kilowatts of energy annually through insulation made of recycled materials and rock wool, the company said in a statement.

Also, the factory has saved more than 6 million gallons of water to date through rainwater collection. In addition, a 66-acre solar park, the largest in Tennessee, was installed at the site. The 33,000 solar panels generate 13.1 gigawatt-hours of electricity each year-enough to power 1,200 homes annually, the company said.

The World Environment Center's Gold Medal for International Corporate Achievement in Sustainable Development was established in 1985 to recognize significant industry initiatives in global environmental excellence and sustainable development. Recent recipients of the WEC Gold Medal Award are Unilever (2013), IBM (2012), Nestlé (2011), Wal-Mart Stores (2010), The Coca-Cola Company (2009), and Marks & Spencer (2008).