Developer TIAA Henderson Real Estate has confirmed a start date and that Mace is on board as the early stage contractor for the 24-storey office tower.

The building, which will be erected at 60-70 Mary Axe next to the Gherkin, was initially launched by developer Targetfollow but was delayed by the onset of the global financial crisis.

When the developer entered administration in 2011 it was sold to TIAA-CREF.

The glazed building has been designed to be extremely energy efficient.

Vertical shading fins to the curved facades and glazed double wall cladding to the end elevations reduce solar heat gains to the office space.

Other low energy measures, such as borehole thermal energy storage and energy piles, result in a design with very low carbon emissions.