Canary Wharf was recently named as one of the biggest power wasters in London

A BBC investigation of City buildings showed that companies in the tower are wasting £17m a year by leaving their lights switched on. And other companies are also guilty of wasting power included US investment bank 25 Bank Street and HSBC’s head office.

The study of the City skyline at midnight on a Sunday night was carried out on behalf of the BBC’s Inside Out programme and found a quarter of all lights in the area were left on between 9pm and midnight on that Sunday night. The worst offender was Canary Wharf Tower where the majority of the 30 companies left their lights on their lights on, wasting the equivalent 4.7 million kilowatt hours each year. That is enough to power more than 1,000 households for 12 months and means the tower is emitting the same amount of Co2 as 4,094 transatlantic flights.

In second place came 25 Bank Street, home to a major US investment bank and two other large companies. The lights on there are wasting 3.3 million kilowatt hours which are enough to power 700 homes for a year. And in third position was the HSBC headquarters, a company that is proud of its green credentials. But the survey showed the building is wasting 2.8 million kilowatt hours of electricity a year. Experts estimated the total cost of the wasted electricity bill over the buildings surveyed was £17m.

The study used binoculars to manually count the number of lights on around Canary Wharf, and 28,000 windows were counted. The worst offender was the Canary Wharf Tower, which houses over 30 companies. However, the Canary Wharf Group, who manages the building, said it simply rented out the premises. “Like any other landlord Canary Wharf Group cannot dictate its tenants’ electricity usage,” the company said. “At Canary Wharf, where 100 per cent of the energy comes from renewable resources, some tenants have staff working round the clock, seven days a week which requires higher than usual energy consumption”.