One of the architects that designed the conversion of Faneuil Hall and Quincy Market into a festival marketplace took aim at the current management company’s plans to replace the greenhouse building as part of a series of updates to the property.

Ashkenazy Acquisition Corp. of New York has held the lease on the city-owned property since 2011 and has been unable to find a tenant for the glass-walled structure, which was last occupied in 2009 by Exotic Flowers. The current building is unusable for most of the year, said Leslie Donovan of Tremont Preservation Services, a consultant for Ashkenazy. Bringing the existing building up to code would require replacement of 60 percent of the vertical services and nearly the entire roof, according to Ashkenazy. The replacement building would meet current building codes and would be marketed to retail tenants year-round.

“The area is underutilized and requires a new program to activate the area,” Donovan said at a public meeting Wednesday on the proposed demolition.

But Jane Thompson, who along with her late husband Ben led the architectural team that designed the marketplace redevelopment in the 1970s, argued in favor of saving the structure.

“I hate to condemn a building because of mankind’s lack of imagination,” Thompson said.

Ashkenazy also wants to convert space in the South Market building into a 180-room hotel and add more rent-paying retailers, bars and restaurants to the central food court. The goal, according to the company, is to attract more locals to the tourist destination that opened in 1976.

The new structure, designed by Elkus Manfredi Architects, is one of several new pavilions that would be built on the property if the Boston Redevelopment Authority approves the changes.

The greenhouse is a carry-over from the Faneuil Hall Flower Market, which opened at the property in 1936 and moved into the greenhouse when it was built in 1976.

The Boston Landmarks Commission will review the greenhouse demolition at its May 26 meeting.