Sprint Nextel says its handset vendors must comply with its new environmental design specifications, according to company CEO Dan Hesse’s testimony before the Senate Commerce Subcommittee on Communications, Technology and the Internet.

“Moving forward, every handset vendor who manufactures handsets to operate on Sprint’s networks must produce handsets that meet or exceed Sprint’s new green design criteria and specifications,” Hesse said, according to a transcript of his speech.

Sprint’s new green handset initiative is based on an environmental scorecard it developed together with its handset manufacturers. Hesse said the scorecard will help Sprint and its vendors gauge the degree to which each handset complies with its ecological standards.

The company also expanded its handset buyback program. The program provides an account credit to Sprint customers who turn in up to three wireless devices, regardless of manufacturer or carrier.

“Sprint is committed, for the long-haul, to ‘green’ our business operations, design more eco-friendly handsets, increase industry wireless recycling rates, and remain a leader in our industry,” Hesse said.

Sprint publicly established its 10-year environmental goals in 2008. The goals included securing 10 percent of Sprint’s commercial energy use from renewable sources by 2017, reducing its greenhouse gas emissions by 15 percent by 2017 and ensuring that at least 90 percent of Sprint’s supplier spending goes toward companies that comply with environmental standards.