AUGUSTA – A northeastern grocery chain said Wednesday it plans to build the first supermarket of its kind anywhere that meets a building industry group’s highest environmental standard.

Hannaford Bros. Co.’s plan calls for a supermarket so green that plants will be grown on part of its roof to add insulation and control storm water. The store is to be built on a former high school site in the capital of a state that prides itself on environmental leadership.

“This is a great day in Maine,” said Gov. John Baldacci, who joined Hannaford’s officials for the announcement. He said the 49,000-square-foot store will join a growing list of state and private buildings that require minimal energy, adding, “We are leading by example.”

As of this spring, Maine was the only state in which state-owned buildings buy 100 percent of their energy from renewable sources, and was one of the first to use biodiesel to heat state offices. It is home to New England’s largest utility-grade wind farm, with at least three more proposed or under regulatory review.

The proposed Hannaford market would be the U.S. Green Building Council’s first platinum-certified “green” grocery store in the world, said the chain’s president and CEO, Ronald Hodge. The nonprofit’s council’s system carries ratings of silver, gold and platinum, the highest.

“We can think of no better place for Hannaford to invest in a first-in-the-world environmental design,” Hodge said.

Hannaford, which is based in Scarborough, wants to build its store on the former site of Cony High School. The project has been challenged in state courts by those who say it would violate a 19th century trust agreement of Daniel Cony, who wanted the site limited to educational uses.

A judge’s decision in favor of the project has been appealed to the state’s supreme court.

A new high school has replaced the building that now stands vacant on the proposed supermarket site. The proposed store is being touted as a kind of educational site itself. Hodge sees it as “a research laboratory” for the company to test new innovations that lower energy usage, waste and water consumption.

By pursuing the platinum designation, the company commits to a design including features such as solar photovoltaic panels, geothermal heating and cooling, high-efficiency refrigeration, energy-efficient lighting and an advanced recycling program, not to mention the vegetation-topped roof.

It’s estimated that the store will be 40 percent more energy-efficient than the industry standard, said Megan Hellstedt, Hannaford’s environmental sustainability manager.

While the platinum rating system encourages the company to recycle 50 percent of the old high school building on the construction site, Hellstedt said the company’s goal is to recycle 95 percent of the building and its contents.

Some residents of the nearby neighborhood object to the proposed store, not just because they believe it violates the long-standing Cony trust.

Jerry Bumford of the East Side Neighborhood Network said neighbors are mostly concerned about traffic from shoppers as well as delivery trucks the market will draw to local streets.

Bumford said local traffic levels have eased during the last couple of years thanks to a new bridge that crosses the Kennebec River on the city’s north side, but “putting a Hannaford’s here is going to bring that right back.”

Hannaford operates 160 stores throughout the Northeast. The new store would replace an older Hannaford market a couple of blocks from the new site.

The nonprofit U.S. Green Building Council is represented by all segments of the building industry to promote buildings that achieve high environmental standards.