Image courtesy of Perkins + Will

A South Boston office property once eyed for multifamily housing has been acquired by a lab developer for $23.5 million.

San Diego-based Phase 3 Real Estate Partners bought the 7 Channel Center property from Westbrook Partners this week, seven months after the Boston Planning & Development Agency approved construction of a 99,500-square-foot office and R&D project.

Westbrook Partners submitted plans in 2022 to demolish a vacant 3-story office building on the property in favor of a 9-story, 99,500-square-foot office and R&D building. Westbrook bought the 0.3-acre parcel from Boston-based Berkeley Investments in 2020 for $12 million.

The approved plans, designed by architects Perkins + Will, include reconstruction of the facade on the lower three floors of the existing 1914 building, and a contrasting modern facade for the six floors above.

Under Berkeley Investments’ ownership, developers presented preliminary plans for a 20-story apartment tower on the site in 2016.

This week’s transaction expands Phase 3 Real Estate Partners’ life science portfolio in the neighborhood, which includes 12 Farnsworth St. and 5 Channel Center.

In June, the BPDA board approved Phase 3’s plans to convert the 55 Summer St. office complex at Downtown Crossing into nearly 155,000 square feet of life science space.