Bloomberg have officially opened their £1 billion European headquarters in the City of London in what the London mayor has called a "vote of confidence" for the British capital.

Speaking at the official unveiling of building, the mayor of London Sadiq Khan thanked Michael Bloomberg for sending a "clear message to the world about the value of investing in this great city."

"We believe that environmentally-friendly practices are as good for business as they are for the planet," Bloomberg founder Michael Bloomberg said.

"From day one, we set out to push the boundaries of sustainable office design - and to create a place that excites and inspires our employees. The two missions went hand-in-hand, and I hope we've set a new standard for what an office environment can be."

Bloomberg added: “London is the business capital of Europe and I think it will remain the business capital of Europe.”

Home to 4,000 employees, Bloomberg's headquarters are located on Walbrook Square in the City of London on 3.2 acres. The buildings will have 500,000 square feet of office space, a 250-seat theatre, 18 restaurants, 4600 desk spaces, two public spaces and a new bank.

Responsible for the building's design, Foster and Partners founder Norman Foster met with Bloomberg with the aspiration to create one of the most sustainable in the world.

"The deep plan interior spaces are naturally ventilated through a ‘breathing’ façade while a top lit atrium edged with a spiralling ramp at the heart of the building ensures a connected, healthy and creative environment," he said.

In Australia, Foster and Partners have designed the $1.5 billion Circular Quay tower and sevens stations for Sydney metro. Norman Foster was awarded the Pritzker prize -- architecture's most prestigious prize. In London, the firm is responsible for Wembley stadium, City Hall, the Millennium Bridge and the Gherkin, amongst others.

Recent projects from Foster and Partners include an Apple Store in Chicago and Canada's tallest skyscraper.

Compared to a typical office building, the new Bloomberg building's environmental strategies deliver a 73 per cent saving in water consumption and a 35 per cent saving in energy consumption and associated CO₂ emissions. Innovative power, lighting, water and ventilation systems account for the majority of energy savings.

Designed to utilise waste products, respond to the building’s external environment and adapt to its occupancy patterns, many of these solutions are first-of-a-kind.