The owner of a long-planned office development in Herndon is now shifting to mixed-use to help kick-start construction.

Quadrangle Development filed plans with Herndon's Planning Commission to build 1.5M SF on the Fairbrook Park site, including two office buildings and two residential buildings, RestonNow first reported.

The developer acquired Fairbrook Park, a 28-acre site at the intersection of Herndon Parkway and Fairbrook Drive, in 1984, property records show. It has built one office building on the site, a two-story structure totaling 80K SF.

The site has long been planned to include three additional office buildings and a hotel, but the developer is now pivoting plans to add residential and retail to the mix. Walsh, Colucci Senior Land-Use Planner Elizabeth Baker, who filed the application on behalf of Quadrangle, told Bisnow Monday the developer is shifting plans because it was unable to sign a pre-lease to break ground on the office buildings.

"It's not like they don't want to develop it, but they've been marketing it for decades and nothing has come to pass," Baker said. "Mixed-use is more attractive to potential office tenants who want a more interesting and lively environment. That's the purpose here, to try to bring this plan up to 2020 standards and get away from the old-fashioned office park."

The new plans call for four buildings: a 19-story office building totaling 360K SF, a 10-story office building totaling 240K SF, an eight-story residential building totaling 470K SF, and an eight-story residential building totaling 410K SF. The project would also include up to 10K SF of retail on the ground floor of one of the residential buildings.

The developer hopes to break ground as soon as possible on the first residential building with retail, Baker said.

"This is within a half-mile of Metro, it's very walkable, and we think this is a great opportunity for the town and also for Quadrangle to create a real community and develop a new project for Herndon," Baker said.