This article has presents an extensive survey of the state of the art in Green IT/S. The findings of the survey suggest that there is scope for a reliable carbon footprint auditing tool for organisational ICT usage. A prototype auditing tool is developed and a trial audit carried out and evaluated. Conclusions include the need for automation of the audit, the need for consistent management of hardware within organisations, and the need to present carbon footprint data in a format that respects the privacy of the individual user, but allows meaningful conclusions to be drawn.