The campaign, created by WWAV Rapp Collins London, will run from November 21 to December 7.
Posters will feature the familiar British Gas flame in green, in contrast to the customary blue, against the words "it won't cost the earth".
The posters will appear in gyms and at Tube and train stations, and press ads will appear in the Metro and Evening Standard.
British Gas says it is looking to connect with London's "young, urban and cosmopolitan" audience with the hope that if they are switched onto environmental issues, they will turn to renewable electricity.
Andrew Reaney, head of residential energy at British Gas, said: "We are talking directly to existing British Gas customers and those who want to switch from another provider to electricity from renewable sources.
"As there are no additional costs involved in making the switch, this is a simple and painless way for someone who wants to play their part in protecting the environment to do so."
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .
_1.jpg)
.jpg)
