And Picadilly's iconic advertising will be turned off for the first time since the end of WWII.
Private homes are also being encouraged to turn their lights off at 9pm in order to save energy.
Comparison website moneysupermarket.com estimates that as much as 900,000 kWh of energy could be saved thanks to the measure.
This could be as much as 36 million kWh of energy if all non-essential electrical appliances are also switched off across UK homes.
"In just one hour, a single household can save about £1.15 by switching off a range of appliances, or £30 million across the UK," said Paul Schofield, head of utilities at moneysupermarket.com.
"While this campaign will help us think about energy consumption, it would be fruitless financially if we were languishing on an expensive electricity tariff."
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.