Supermarkets are notorious energy guzzlers: They’re lit like car lots, sometimes 24 hours a day. There are bays and bays of freezers and refrigerators, the latter of which often don’t have doors. They’re tricky to efficiently heat and cool.

But energy costs and environmental concerns have prompted a green supermarket trend.

Some grocers are installing LED lighting that consumes only a quarter of the energy of conventional bulbs; others are reclaiming air from their refrigeration units and using it to cool the store.

Some Kroger stores use thermal imaging cameras to detect energy waste in cooler cases.

Whole Foods Market uses solar power in some stores, and has bought renewable energy credits from wind farms to offset its electricity usage.

Nationally, Food Lion and Harris Teeter are participating in a program with the Environmental Protection Agency to phase out refrigerants known as hydroflurocarbons, which deplete the ozone layer. Naturally occurring carbon dioxide gas can be used as a coolant instead.

And you, the shopper, can influence grocers’ environmental practices. Talk to the store manager if you have suggestions, such as offering more locally grown food, which isn’t trucked or flown thousands of miles. Healthy, organic bananas from Colombia have a ginormous carbon footprint. Take a pass.

Be attuned to your buying habits. The canvas shopping bag is de rigueur and no longer solely for the granola crowd. (Hey, if you can imagine it, yogurt used to be exotic, too.) Ask if the store recycles packing materials and how it disposes of its waste. Don’t be shy. The store wants your moneybadly.

University of Missouri researchers are studying how shoppers respond to refrigerators with glass doors versus refrigerated open display cases. The lore is supermarkets are reluctant to use more energy-efficient glass doors because the barrieralthough transparentreportedly reduces shoppers’ impulse buying. C’mon, if you’re going to buy the cookie dough, at least burn the calories to open a refrigerator door.