Science Park has taken another step forward in its transition from an industrial wasteland to a livable area.

On Wednesday, the City Plan Commission approved detailed measures for the renovation of two vacant Winchester rifle factory buildings into 158 new loft-style apartments in Science Park. The project, which is called Winchester Lofts, will cost about $50 million and will be undertaken by Forest City Enterprises, an Ohio-based development company. Despite the City Plan Commission’s unanimous approval of the plan, some local residents question the building’s parking space and lack of retail.

“These are very complicated projects and this is an important step in the process,” said Abe Naparstek, the vice president of Forestry City Residential Group, “[Forest City Residential Group is] moving very quickly to finish all the construction documents so we can start construction in the spring.”

The renovations are the second phase of the city’s effort to redevelop Science Park. While the area once thrived with industrial factories, like Winchester Repeating Arms Company, which was once the city’s largest employer, most of the buildings have since been abandoned. In recent years, the city has heightened efforts to revitalize the area with increased development. This March, Higher One, a financial services and technology company that employs over 500 and serves colleges and students, moved their offices into the Winchester Arms factory.

Kelly Murphy, head of economic development for the city, said that when she took her job six years ago, the area was only 10 percent occupied.

“It was slow going for a long time. Most of the buildings hadn’t been fully renovated. All the factories had broken windows,” Murphy said. “In the last six years, a lot has happened to renovate the existing buildings, bring new tenants in and create new facilities.”

The Winchester Lofts, the second phase of the city’s plan for Science Park, will add residential space to the neighborhood. The buildings will have classic loft-style apartments that showcase the historic wooden frame of the building, Naparstek said. The building will include 28 studios, 94 one-bedroom apartments and 36 two-bedroom apartments. Twenty percent will be set aside as affordable housing, he added.

The funding for the project is a combination of state and federal tax credits and a grant from the state of Connecticut for affordable housing, Naparstek said, adding that the “vast majority” of the funding has been secured.

Some residents have raised concerns over the project’s plan for parking and its lack of retail space, with the current plan featuring one or two parking spaces per unit.

“I question the necessity of having that many parking spaces,” said Ward 10 Alderman Justin Elicker, who previously served on the City Plan Commission.

The optimal amount of parking is a little less than one parking spot per apartment unit, he added, describing the amount of parking currently planned “wasteful.”

The plan approved Wednesday also eliminated retail space that had been a part of the project’s early concept. Napstarek said the move to a fully residential building was in the best interest of the neighborhood in the long-run, because it will fill the neighborhood throughout the entire day instead of leaving it empty at night when shops close their doors.

Murphy said that adding residential space will help to fill existing, vacant retail across the street from the site.

“Retail follows roof,” she added.

The plan still needs the approval of the city’s Development and Redevelopment Commissions in the next month. If approved, construction will likely start in late spring or summer of next year.

Elicker said he hopes that the permanence of the neighborhood as a result of the new housing will spur economic development in the area. He added that if the project is successful, it may enhance New Haven’s image as a safe place for developers to invest.

“We have less than a 2 percent vacancy rate for rental units. Particularly in downtown, we have a very strong rental market,” Murphy said. “We need to produce more.”

New Haven’s population grew by 4.98 percent between 2000 and 2010, the first time it has increased in 60 years, according to census data.

Correction: Oct. 24

A previous version of this article inaccurately described the startup Higher One and mistakenly stated that it moved into the Science Park neighborhood last March. In fact, it has been in Science Park since 2004 and decided to move to the Winchester Arms factory in March.