To measure the overall "greenness" for its recently released ratings, Greenopia looked at factors such as how transparent the company is about its energy consumption; how easy it is for passengers to purchase carbon offsets; how much recycling is done on flights; and how much the company spends to research alternative fuels. Greenopia even looks at whether onboard food is organic, locally sourced or sustainable.
In nearly all these areas, Virgin America was the leader, said Doug Mazeffa, Greenopia's research director, who put together the report.
"Virgin is just doing a great job," he said, pointing to Virgin's use of the environmentally friendly Terminal 2 at San Francisco's airport and the airline's pledge to use 10% alternative fuel blends by 2020. The company recycles 47% of waste on flights and has a goal of 50% by 2012, according to its website.
But it's not just Virgin America that impressed Mazeffa, who has written this report for three years now, as well as compiling similar reports for other industries.
"It is really staggering how quick the improvement has been in terms of the airlines' environmental impact," he said. "Companies are usually happy with 2% to 3% change in a year. In the airline industry, we are seeing companies reducing their footprint 30% to 40% to 50% in the past decade. We are talking about millions of tons of C02 that is no longer going into the atmosphere."
As for the airlines that didn't fare as well: The three lowest-rated companies on Greenopia's list are United Airlines, US Airways, and, in last place, American Airlines.
But Mazeffa added that although American Airlines has an older fleet and higher emissions per revenue passenger mile, it still earned one green leaf on Greenopia's rating system, which rates the companies from zero to four leaves.
"No one is doing a horrible job, which is great," he said.