The retailer, which in addition to its solar and wind energy goals is working to reduce the waste in its system and make its supply chain more environmentally sustainable, has seen shares fall 27% this year on concerns about its ability to compete with the likes of Target (TGT), Amazon.com (AMZN), and Kroger (KR). It is also spending $1.5 billion on giving workers’ raise to achieve a broader goal of improving in-store service, and also pouring a fortune into its e-commerce.

But those pressure haven’t deterred Walmart from pursuing its sustainability goals.

“Every publicly traded company goes through these points where they are trying to stay focused on long and medium term goals but also the realities of short-term P&L [profit and loss] pressure,” said Dan Bartlett, Wal-Mart Stores’ executive vice president of corporate affairs, at Fortune‘s Brainstorm E conference in Austin, Texas. (Please click here to watch the sessions over the Internet.)

“The bottom line is that we have to be able to walk and chew gum,” added Bartlett, who oversees the company’s sustainability efforts.

One of Walmart’s goals is to get 7 billion kilowatt-hours of renewable energy by 2020. Nearly 1,300 of its suppliers (which make 65% of what Walmart sells) now use its Sustainability Index—and by the end of 2015 Walmart will have eliminated 20 million metric tons of greenhouse-gas emissions from its supply chain.

The company stands to save hundreds of millions of dollars a year thanks to its sustainability efforts, Bartlett added. That can end up being plowed back into the business and fund price reductions for customers.

“There can be what is known as a double and sometimes triple bottom line : it’s good for business, it’s good for our stakeholders and its good for society and that’s the prism through which we make these decisions,” Bartlett said.

Click here for more coverage of Fortune’s Brainstorm E conference.

For more on Walmart, watch this Fortune video: