"The bigger they come, the harder they fall” is an axiom that has been ascribed to everything from trees to celebrities. Large-format value retailer power players are working hard to prevent it from being applied to them any time soon. In addition to keeping their financial houses in order, they all are polishing their altruistic credentials in order to show a beneficent side to the public, whether it is championing environmentalism, cutting prescription prices or espousing other forms of good corporate citizenship.

The current economic environment has been a boon to value retailers like Wal-Mart, Costco and Target. This provides ample resources and opportunity to build energy-efficient stores and stock their shelves with healthier, more natural and “greener” merchandise.

At Costco, for instance, CEO Jim Sinegal spent a good part of his annual shareholders address touting efforts to reduce the company’s carbon footprint. A half-dozen stores are equipped with solar panels, and at least that many are having them installed this year; skylights also are being employed to cut down on electric lighting. Just about everything that can be is being recycled, from shipping pallets to the plastic used to shrink-wrap merchandise. Consumer-goods packaging is being rethought so more units can be shipped per carton, pallet or truckload, thus saving on fuel.

Target paid Mother Nature props with a line of eco-couture first available at Barneys New York (which did nothing to damage Target’s cheap chic rep). Next year, two new store prototypes will debut. They will be larger than existing Target stores, green-certified and devote more space to food and electronics.

Wal-Mart is writing the book on eco-friendly approaches to store design, while pressuring suppliers to cut down on wasteful packaging and giving consumers options on everything from energy-efficient light bulbs to organic dairy goods and produce.