Google said: "Last year we released a paper on the energy savings from using Gmail instead of locally hosted email. Here, we expand on that analysis to include the cloud-based office applications of Google Apps. Our estimates, which we’ve supported with a case study from a Google Apps client, show that migrating basic IT applications to Google Apps significantly reduces energy consumption and carbon emissions. Based on our analysis, a typical company or organization that migrates to the cloud could:

• save an estimated 68–87% in energy for its office computing

• reduce similar amounts of carbon emissions

These findings are consistent with a case study presented in a paper of the actual savings achieved by the U.S. General Services Administration (GSA), a Google Apps client with approximately 17,000 users. By switching to Google Apps, GSA reduced server energy consumption by nearly 90% and carbon emissions by 85%."