It's quite tempting to dismiss Dell's claim today that since 2005 it has saved consumers $3 billion in energy costs and spared the environment 29 million tons of CO₂. The savings, says Dell, came through power management and energy efficiency features found on the OptiPlex desktop, Latitude laptop, and Precision workstation.The numbers are important: Product use is the largest single overall contributor when considering all direct and indirect sources of CO₂, says Dell. But Dell can't be sure how many users keep the default power-saving settings on, or how many hours they use their machines. And while Albert Esser, VP of Power & Infrastructure Solutions, says Dell has been "conservative in these numbers," they remain unverifiable.

The numbers I expect to find more compelling are due in 2009: the emissions data contained in the Carbon Disclosure Project's Supply Chain Leadership Coalition report. As a member of that coalition, Dell requires its primary suppliers to report CO₂ emissions data during quarterly business reviews. The goal, says the CDP: "to better understand how companies in their supply chains are considering climate change and working to reduce their greenhouse gas (GHG) emissions. ... Extending disclosure into the supply chain will massively accelerate the corporate response to climate change."

Not all suppliers' data is verifiable, either. But there is an increasing tendency among larger suppliers to have their results verified by third-party sources. That is true among one of Dell's largest suppliers, AMD, which has its own aggressive environmental protection efforts.

Until audited supply chain numbers are available, the most compelling data are Dell's direct emission numbers. According to Dell's CDP filing, it directly emitted 35,128 metric tons of CO₂, including 15,263 metric tons in Kyoto Protocol Annex B countries (the European Union and 13 other countries, including non-signatory United States), from February 2007 to February 2008.

Dell also released 403,210 metric tons of CO₂ as described in the Greenhouse Gas Protocol Scope 2, including 242,577 metric tons from Annex B countries.

By comparison, Hewlett-Packard emitted 102,552 metric tons of CO₂ between November 2006 and October 2007, including 86,204 metric tons in Annex B countries. HP also emitted 1,415,555 metric tons of CO₂ covered under Scope 2.

And Cisco emitted 65,971 CO₂ metric tons in Scope 1 emissions, including 55,391 metric tons in Annex B countries. Cisco also emitted 479,202 in CO₂ metric tons covered under Scope 2, including 379,674 in Annex B countries.