Steak is the first digital agency to be appointed to the role. Working pro bono, it will provide paid search management and online media planning services to promote the Start website.
The website, Startuk.org, highlights examples of sustainable practice and explains the issues around sustainability in a jargon-free manner. It will relaunch later this year.
Start, a not-for-profit organisation, is an initiative of The Prince Charles Foundation and is planning an array of activities this year to engage people in its cause. It was launched in February at the Museum of Science and Industry in Manchester.
Steak's other clients include John Lewis, Debenhams, British Gas and Visit London.