Peter Cooke is a numbers guy. So it’s no surprise he’s taught his children to count supermarket floor tiles and calculate how much more sustainable the store could be.

Most open refrigerated display cases have air curtains, barriers of forced air flowing between vents lining the lower edge of the case and vents running along its upper edge. An air curtain helps keep cold air inside the case. When anything physical – say a customer’s arm reaching in to grab a package of bacon – breaks the curtain’s plane, refrigerated air escapes.

Easy customer access is the point of any open display case in a grocery store, so that particular instance of cold air escaping is, well, inescapable. But many times, packages of bacon get jostled during the selection process and fall onto the case’s bottom vent, disrupting the curtain for however long the package sits there.

While grocery shopping with their parents, Cooke’s kids walk along the cases and count how many air curtain disruptions they find. Since they know that every foot of disrupted air curtain flow results in 27 cents per day in wasted energy, if they count 10 tiles worth of blocked air curtain, they can deduce the store has lost $2.70 in wasted energy costs that day. They also understand that pushing any merchandise out of the way of the air curtain’s flow is the right thing to do, both in terms of fostering a greener environment and helping the store’s bottom line.

Cooke explains that since grocery profit margins are so tight (the average American supermarket that pulls in $18 million in sales annually makes a slim $370,000 profit), a store must sell $17 worth of merchandise to make up every dollar wasted on inefficient energy use.

When he’s not teaching his own kids about the prospect of a more sustainable grocery store, Cooke works for Manomet, a science-based, nonprofit organization that works on practical applications of sustainability principles across business sectors; he works out of Manomet’s Brunswick office as program manager for its Grocery Stewardship Certification initiative.

Those hard numbers have helped Cooke convince managers in 700 grocery stores across 15 supermarket chains nationally, including Hannaford, Stop & Shop and Whole Foods, to identify ways to curtail storewide energy waste; promote recycling; divert food waste from landfills and incinerators; and give local and organic products recognizable, systematic placement on their shelves.

Typically, designated green captains in each store seeking certification work with a Manomet representative to fill out a 260-question survey that explores how well an individual facility and its procedures address two dozen areas of sustainability. When a grocery store chain certifies a pilot number of stores, Manomet staff goes on site to educate and engage employees in the process as well as verify survey answers. If a chain chooses to then certify all of its stores, Manomet audits a representative sample of the survey results. Stores must achieve 150 out of a possible 285 points to earn Manomet’s certification.

I walked with Cooke through Hannaford’s Forest Avenue store in Portland, which he says is one of the highest scoring certified stores in the country, to learn what to look for.

It starts in the parking lot. Do signs remind customers to bring their reusable bags into the store?

Once you enter the store, are you immediately presented with opportunities to recycle plastic bags, glass bottles and metal cans? When you look up, do you notice energy-efficient spot lighting and ceiling fans redistributing warm air collected from the compressors that are keeping the refrigerator cases cold?

In addition to checking to see if display case air curtains are intact as the Cooke children do, also look at the tops of the vegetable display cases for the metal handles of mesh curtains that can be pulled down when the store closes. Cooke says each curtain saves $35 per year in energy costs and helps maintain moisture levels, keeping produce fresher longer and reducing overall food waste.

While in the produce section, ask an employee if the store sends its food waste to a compost facility, a pig farm, a waste-to-energy plant or the landfill.

Coffin coolers in the meat department should have sliding doors (they save $40 per case per year in energy costs, Cooke says), and displaying seafood on cold stainless steel instead of ice and using low-flow, blue-nozzled sprayers can reduce water usage in that department.

In the dairy aisle, note if the cases have doors and are equipped with sensors so that LED lighting inside illuminates only when a customer approaches.

While it was all the rage 10 years ago for a grocery store to assemble local and organic products in a single section of the store, Cooke says recent studies show that those products are more likely to be purchased if they are housed close to conventional products of the same type.

“Say you’ve been shopping for 30 minutes when you realize you forgot to grab the local eggs from the special section near the produce, and you’re now standing in front of a wall of conventional eggs. Are you really going to hike back across the store to get the local ones?” Cooke asked rhetorically.

Under his program, for a store to earn sustainability points selling local and organic products, they need to be integrated throughout the store yet highlighted as greener options with ample signage.

Cooke’s kids aren’t the only shoppers who care whether or not grocery stores are operating on a greener plane. A 2015 study conducted by the market research firm Cone Communications showed that 77 percent of the respondents care about the sustainability parameters of their supermarkets.

“Whether or not a green certification plays into their choice of which grocery store they use regularly remains to be seen,” Cooke said.

Perhaps letting store managers know we’re looking hard at the green steps they are taking will move things along in the right direction.

Christine Burns Rudalevige is a food writer, a recipe developer and tester and a cooking teacher in Brunswick, and the author of “Green Plate Special,” a new cookbook from Islandport based on these columns. She can be contacted at cburns1227@gmail.com.

Ingredients for Crispy Pork and Vegetable Rice Bowl. Staff photo by Derek Davis

CRISPY PORK AND VEGETABLE RICE BOWLS

As you source ingredients for this quick, easy weeknight meal, look for evidence that your grocery store is taking steps to make supermarket shopping as sustainable as possible.

Serves 4

2 tablespoons local honey

Zest and juice of 1 lime (about 1/4 cup)

2 tablespoons rice vinegar

1 tablespoon Asian fish sauce

1 tablespoon minced chili pepper

2 tablespoons vegetable oil

8 ounces sustainably raised ground pork

4 scallions, white and green parts chopped separately

1 tablespoon chopped garlic

1 tablespoon chopped ginger root

1/4 cup chopped cilantro

3 cups hot, cooked rice

1 cup thinly sliced red bell peppers

1 cup shaved local carrots

1 cup diced cucumber

1/2 cup unsalted roasted peanuts, roughly chopped

To make the sauce, combine 1/4 cup warm water and honey in a medium bowl. Stir until the honey dissolves. Add the lime juice, vinegar, fish sauce, and chilies; set aside.

Pour the oil into a large skillet, and heat over medium high heat. Add the pork, breaking it apart with a wooden spoon until it is brown and crispy, 6 to 8 minutes. Stir in the chopped white parts of the scallions, the garlic and ginger. Cook 1 minute. Remove the pan from heat. Stir in half of the reserved sauce and all of cilantro.

Divide the hot rice, red peppers, carrots, cucumbers and chopped green parts of the scallions among 4 four bowls. Top with equal portions of the pork mixture and chopped peanuts. Serve immediately with the remaining sauce.