The proposals, submitted by Bruntwood SciTech, combine a full refurbishment of the existing 21-storey tower with a four-storey extension, increasing total floorspace to around 160,000 sq ft.

Under the plans, the 131,000 sq ft building will be modernised throughout while retaining its original architectural character.

The four-storey extension on Portland Street and Sackville Street will include a double-height reception, communal social spaces and open staircases linking flexible work and hospitality zones.

Inside the existing tower, all windows would be replaced and the facade refreshed, alongside rolling upgrades to office floors and core areas including lifts, stairs and washrooms.

The redevelopment is designed to support Bruntwood SciTech’s net-zero ambitions, with gas-fired boilers removed and replaced by heat pump systems, a new electrical substation installed to support electrification, and smart building systems introduced throughout.

The project team includes Bridge Architects and Cubicworks, with construction targeted for completion in early 2028.

Matthew Morten, building and construction director at Bruntwood SciTech, said: “Manchester One has been an enduring fixture of the city for decades and is synonymous with Manchester’s skyline.

“These proposals represent our commitment to ensuring it remains both sustainable and inspiring, and the £17m investment is a clear statement of intent about the building’s importance to both our portfolio and to Manchester.”