Minneapolis real estate developer Stuart Ackerberg says he wants to "change the energy" of the Uptown landmark Calhoun Square.

Ackerberg, CEO and owner of the Ackerberg Group, confirmed Tuesday that his firm is under contract to buy the retail center, plus an adjacent parking ramp and potential development parcel, from current owner BlackRock Inc. He declined to reveal the purchase price. The deal is expected to close by mid-April.

He hopes to reposition the property, at the busy intersection of Hennepin Avenue S. and W. Lake Street, but said it's too soon yet to go into detail.

"I'd like to change the energy of the center," Ackerberg said. "It's not very inviting now. It's not a place you'd want to stay and hang out."

Calhoun Square opened in 1984 and, over the years, suffered a bit of an identity crisis as owners weathered economic cycles and tried to balance the mix of national and independent stores.

In 2007, the center changed hands for the second time in three years, when BlackRock, a New York investment firm, bought it for $47.3 million.

During BlackRock's ownership, trendy Swedish clothing retailer H&M opened a 23,000-square-foot, two-level store. And CB2, an offshoot of home superstore Crate & Barrel that targets a younger, hipper, demographic, arrived in 2011.

The center is now 88 percent leased. Major tenants include Kitchen Window, Bay Street Shoes, LA Fitness, CB2, Famous Dave's, Chiang Mai Thai, Republic and Sushi Tango.

"We see it as a critical component to Uptown," Ackerberg said, adding the center shapes "people's perception of the area."

Privately held, the Ackerberg Group has developed, owned and renovated more than 4,000 apartments or condominiums and over 7 million square feet of retail, office and industrial property over the past 40 years, according to its website.

The firm already has a strong presence in Uptown, with many projects completed or in the works. It developed the Mozaic mixed-use complex, which features office and restaurant space behind the Lagoon Theater and next to the Uptown Transit Center. A second phase to that project has begun.

Other Ackerberg projects in Uptown include the Lake Calhoun City Apartments, 157 units that skirt the Midtown Greenway; Lumen on Lagoon, a mixed-use commercial project; and several renovations, including the Romy Building, built in 1923 and remade into offices and retail shops.

A vacant parcel of land along Lake Street between Girard and Fremont Avenues is part of the deal and essentially a blank canvas for Ackerberg. He said he's exploring a number of possibilities for the site, perhaps retail and office space.

"My goal has been to expand the daytime population of Uptown," he said.

Maude Lovelle, executive director of the Uptown Association, welcomed the news, especially since Ackerberg's firm has been a long-standing member of the group. She said changes at Calhoun Square in recent years have "transformed" the center. "I think it's favorable to have a mix of nationally known businesses and the type of businesses that are more unique and one-time only businesses," she said. "I'm sure anything [Ackerberg] does will be extremely positive for our community."

Janet Moore • 612-673-7752