Under the new guidelines energy suppliers' tariffs will only be considered green if they provide environmental benefits above the existing legal obligations all suppliers must adhere to.
Juliet Davenport, the chief executive of small independent energy provider Good Energy, said her company would be signing up to the scheme.
She added: "We are pleased to see these guidelines emerge and to be the first independent supplier to have signed up. Good Energy has been calling for more formal guidelines on green supply for several years."
In related news, campaigners have called into question the government's claim that greenhouse gas emissions have fallen by 1.7 per cent.
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.