GUILDERLAND — Joining the crowd of proposed apartment complexes in Guilderland is one that would bring 120 units to the existing Great Oaks commercial office park off Church Road, just west of the Northway, on the south side of Route 20.

This project would add two new apartment buildings to the existing Great Oaks complex, which now consists of three office buildings.

The Rosenblum Companies, the developer that owns Great Oaks, says that office-space rentals are lagging. The apartment buildings’ amenities would be open to office tenants and would, the developer hopes, make the commercial space more attractive to potential tenants. The company did not return a call asking for comment.

The new apartment buildings would be four- and five-storied, while the office buildings are two- and three-storied.

The application is for a Planned Unit Development, a rezone that requires a new local local law. The town board is the lead agency on PUD applications. The site is within a Business Non-Retail Professional, or BNRP, zoning district.

There is no set maximum height or number of storeys for projects proposed as Planned Unit Developments, said town Planner Kenneth Kovalchik. Those matters are determined for each PUD by the town board.

A narrative with the application says that office-space rental is lagging. Many companies now demand amenities not present at the complex, and more workers are able to work flexibly, from home, reducing the need for office space, the narrative says. Many companies are beginning to use “coworking” facilities that can be rented without lease commitments, it says. It notes that Great Oaks has experienced attrition and longer vacancies, “which are typically 9 to 24 months and in some cases longer.”

The narrative gives the example of General Electric, which it says opted in 2016 not to renew long-time leases at Great Oaks that totaled over 25,000 square feet, or about 12 percent of the complex’s square footage; over 11,000 square feet of that space still remains vacant.

Access to the site would be unchanged, through the current entrance onto Church Road from Great Oaks Boulevard.

The five-story building would be about 175,000 square feet and contain 78 apartments and an “internal garage” of 124 parking stalls. It would also have amenities to serve both residents and office tenants, including a market/café, a fitness room with showers, bicycle storage, and an outdoor patio. It would have a footprint of about 26,000 square feet.

The four-story building would be about 65,000 square feet, with 42 apartments and 32 internal garage parking stalls. It would have a footprint of about 17,000 square feet.

The application also calls for adding parking garages on the ground floor of each new building, with the apartments above.

According to the application, the project would not add significant traffic to the studied intersections of Western Avenue and Church Road and the McKownville United and Church Road/Great Oaks Boulevard.

The project would generate 53 new trips during the weekday p.m. traffic peak hour, which would mean “no changes in level of service between no-build and build conditions,” the application says, adding that the state’s Department of Transportation requires detailed analysis of off-site intersections only if a project would generate at least 100 trips on any one approach.

The Rosenblum Companies has a total of over a million square feet of office, industrial, retail, self-storage, and mixed-use properties in the Capital District. The application says that the Great Oaks complex has attained Energy Star certification and has a rooftop solar-panel system and porous-pavement parking lots to mitigate stormwater runoff. The complex also uses green-certified cleaning products, construction material, and carpet tile recycling, as well as annual days for recycling of electronics and offers tenants, free of charge, charging stations for electric vehicles. Rosenblum has won several “green” awards, including from the town of Guilderland, according to the application.