PROVIDENCE — The Arcade building on Westminster Street, the oldest indoor shopping mall in the nation, is slated for an $8-million renovation starting this summer, and the businesses inside have been given until the end of June to clear out.

Owner Granoff Associates, which owns several prominent properties in the Financial District, plans to install modern heating and air-conditioning systems in the 180-year-old building, and may also modify it to serve a single large tenant.

The building now houses 13 small shops and restaurants, and has many more storefronts vacant. The building has been a consistent money loser for years, said Evan Granoff, who is betting that luring a large single tenant could make the historic structure profitable.

“It was losing money hand over fist,” Granoff said, claiming losses of $10,000 a month. “The goal has been to get an anchor tenant in there.”

The remaining businesses learned of their ejection yesterday from media reports. Shock resonated through the Arcade’s three stories.

“There’s been people crying in here all day,” said Don Beohner, who has owned the jewelry store Copacetic in the Arcade since the 1980s.

“Everybody’s shocked that we’ve only been given 30 days notice. How does anyone move a business in 30 days?” he said. “It’s just really sad. This is where I’ve been for 23 years.”

The businesses in the Arcade have operated on month-to-month leases since the Granoffs took full ownership of the property in February 2006. Since then, nearly 20 businesses have closed their doors and the Granoffs have not accepted any new tenants, knowing that they would renovate the structure.

Installation of modern heating and cooling equipment will begin shortly after the businesses leave at the end of June. The Arcade lacks air conditioning, and in the summer the heat can be stifling.

“If you ever walk through that thing in July, that thing’s an oven,” Granoff said.

Environmentally friendly technologies and design strategies are planned for the renovation, allowing air to circulate more freely and letting in more natural light. The reopening of long-covered windows on the east and west faces is also planned.

But further plans for the renovation are not yet finalized, as the Granoffs still do not know what kind of large tenant they will get. Depending on how much of the building an anchor tenant wishes to occupy, the Arcade could become a single-store building, or it might maintain some of its current, small-shop model. The small businesses being turned out now could return if that happens, Granoff said.

“If we’re taking people back in there, then yeah they could get back in. But I’m not saying that this use is what it will be. If we can get someone who takes the whole structure, great,” Granoff said.

The project had been expected to start sometime later this year. Then last week, the Arcade’s largest remaining tenant, Johnson & Wales University-owned Johansson’s Bakery, informed the Granoffs that it would be closing its doors and moving to the university’s hospitality facility in Seekonk. The Granoffs decided to start immediately.

“They were a substantial portion of the rent, and the loss just went well out of control,” Granoff said.

State historic tax credits were approved for the project May 15, covering just over a quarter of the renovation cost. The state’s Historic Preservation and Heritage Commission would have to approve any design plans for the protected National Historic Landmark.

“It is important to our family that we are involved in historic preservation in Providence, and the Arcade is certainly one of the most important of our city’s historic structures,” said Lloyd Granoff, Evan’s brother and partner. “Our renovation plans will ensure both the architectural preservation and the long-term economic viability of this treasure.”

The renovation is expected to take a year to complete.

The Arcade was erected in 1828. It struggled at first, and was soon known as Butler’s Folly, after Cyrus Butler, an investor who put $140,000 toward the building’s construction.

The Arcade was first renovated in 1901, when its stoves were replaced with steam heat. It was purchased and rescued from demolition by the Rhode Island Association for the Blind in 1944.

In 1980, a development group led by Gilbane Properties restored the old building, at a cost of almost $3 million, but could not make it profitable. Johnson & Wales bought the Arcade in 1995, and the Granoffs took control in early 2006.

Yesterday, frantic storeowners called the Providence Foundation, a business-backed group that maintains a list of all the retail property available downtown. Director Daniel Baudouin said the Foundation will try to find new homes for Arcade refugees.

“We just became aware of the urgency of the matter. If we can be helpful in finding them new space, absolutely,” Bauduoin said.

That may not be easy, however. There are few empty small storefronts in Providence right now, Bauduoin said.

“We have an 11-percent vacancy rate on first-floor properties. Four years ago it was 27 percent. At the size they need, it’ll be a little more challenging. Maybe we can be creative about subdividing bigger spaces.”

Shop owners say they will meet today to figure out their next step as a group. Meanwhile, yesterday was a day of mourning inside the Arcade’s high granite walls. The Providence Cookie Co. has baked sweets inside the Arcade for 26 years. An employee said they fielded calls all afternoon yesterday from well-wishers, many wondering what the beloved shop would do next.

The day’s receipt should have read “Thursday.” Instead, across the top was a different word: “Doomsday.”

dbarbari@projo.com