BENTONVILLE, — Wal-Mart begins using a scorecard today that will rate its suppliers' progress on making product packaging more sustainable.

The move is a bid to help the world's largest retailer trim packaging materials by 5 percent by 2013. More than 97,000 products are now part of the scorecard from more than 6,000 vendors, and meant as a tool to help Wal-Mart buyers make more informed purchasing decisions.

"It's important to us that our suppliers see the intrinsic value behind sustainability, both for their business and the environment," said Matt Kistler, Wal-Mart’s senior vice president of sustainability. "We’ve made significant progress throughout the first year of the scorecard and it is a key responsibility of our suppliers to input new products and update packaging changes on an ongoing basis."

It's a mammoth undertaking that could yield big dividends. For instance, the initiative could avoid nearly 700,000 metric tons of carbon emissions and save Wal-Mart $3.4 billion.

The scorecard uses several metrics to evaluate product packaging: greenhouse gas emissions, product-to-packaging ratio, space utilization, innovation, transportation-related emissions and the amount of renewable energy used to make the packaging.

The calculations and methodology behind the scorecards will be evaluated by the Packaging Sustainable Value Network, which is made up of government agencies, suppliers, academics and trade groups, among others.

Wal-Mart announced the packaging initiative at the Clinton Global Initiative in 2006. That year, the retailer introduced the scorecard to more than 2,000 private label suppliers. Tools and resources were given to allow the pool of suppliers to learn the process and share the results.