Denver International Airport, a recognised environmental leader in the United States, developed a comprehensive environmental management system that is now certified by the International Organization for Standardization.

The ISO - a 159-country network of national standards institutes - is the world's largest developer and publisher of standards. DEN has been the only US international airport that has ISO 14001 certification for an EMS that covers an entire airport complex.

The certification recognises that Denver's EMS can identify and control the environmental impact of its activities and provide a systematic approach to setting and achieving environmental objectives, demonstrating along the way that it has achieved the objectives.

Since DEN opened in 1995, it has collected and recycled most of the fluid resulting from de-icing aircraft in winter. Seventy five percent of the collected fluid (886,000 gallons in 2008) is processed through an on site recycling plant.

The airport also has a robust waste reduction and recycling programme. In 2008, DEN's hazardous waste volume was down 33% from 2007. More than 1,400 tonnes of non-hazardous materials were recycled, including batteries, electronics, fluorescent bulbs, scrap metal, concrete, asphalt, tyres, carpet, and restaurant grease, among numerous other items.
DEN reduced airport-access fees for taxis that are hybrids, and 55% of the airport's light-duty vehicle fleet runs on alternative fuels.

Within the last 18 months, Denver International built two solar-energy-production facilities. The two-megawatt south facility, with 9,200 solar panels, can create more than three million kilowatt hours of electricity annually. The north photovoltaic complex, although smaller at 1.6 megawatts, can supply the power needs of DEN's fuel farm.

Denver International Airport was built with the environment in mind, Day concludes. "It has always challenged itself to reduce impacts to land, water, and air, while innovating to increase energy efficiency and develop sustainable operations and growth."