The government-funded body has appointed four agencies to the roster: MRM Worldwide, Ogilvy Interactive, Tequila\London and WDMP. It is believed that they will be asked to pitch for briefs on a project basis.
The appointments are part of a wider review of The Carbon Trust's £50m communications assignments that began in October.
The review spans the body's advertising, direct marketing, media planning and buying, contact centre and PR accounts. Pitches for its advertising business are taking place this week, with the remainder of its roster arrangements set to be announced early next year.
In March, the organisation hired McCann Erickson, Manning Gottlieb OMD and Tequila\London to handle a £3m awareness-raising brief, which broke in June.