The majority (57%) of European-based companies have sustainability initiatives written into their company’s travel policy, according to a new study on sustainability in travel programs by the Global Business Travel Association (GBTA) Foundation.

This marks an increase from 39% in 2012; it’s largely attributable to the financial benefits, as well as safety and security enhancements delivered by the programs, according to the GBTA.

The study also found that more U.S. companies are incorporating sustainability programs into contracts (from 11% in 2011 to 19%), but they continue to lag behind European counterparts.

“Overall, sustainability initiatives appear to be more integrated in Europe-based organizations, with opportunity for improvement among U.S.-based organizations,” said Joseph Bates, GBTA Foundation’s vice president of research. “We found that European companies are focused on efforts that result in both financial and environmental benefits, while American companies have a strong focus on the human relations aspect of sustainability.”

Here are some highlights of the study, according to the GBTA:

• The majority of European travel managers (52%) think sustainability is now more important to their organization compared to two years ago.

• Nearly half of Europeans companies find the environmental impact of car rental and rail suppliers to be very important/important (44%, each).

• Safety and security considerations are the biggest driver of sustainability investments in both regions (72% in the U.S. and 74% in Europe). Long-term cost savings (71%) ranked second in Europe, while American companies were focused on contributing to society (68%).

GBTA’s “Sustainability in Travel Programs” study was sponsored by Enterprise Holdings, owner and operator of the Enterprise Rent-A-Car, National Car Rental and Alamo Rent A Car brands. Nearly 300 U.S. and European-based travel managers were surveyed to better understand how they currently view sustainability initiatives and the role sustainability plays with ground transportation.

“It does not surprise me to see sustainability issues rising up the agenda for travel managers,” said Jim Burrell, senior vice president for Enterprise Holdings in Europe. “Sustainability within the travel supply chain has been a core component of contractual discussions for a number of years. However, there is a definite shift to this becoming more about measurement and impact than just a ‘nice to have’.”