A Microsoft article titled "Reducing Environmental Impact through PC Life Cycle and Configuration Management" explains how the company implements sustainability in purchasing, operating, and disposing of its employee computers.

Microsoft IT has taken a complete PC life cycle management approach to ensure that all employee PCs and peripherals:

• Are designed for efficiency. All PCs included in the Microsoft IT Client Standards List must meet Energy Star, Climate Savers, 80 Plus, and EPEAT Gold requirements.
• Operate efficiently, consuming power only when needed. A customized Windows' power plan leverages Microsoft® System Center 2012 Configuration Manager Client Power Management (CPM) functionality to help ensure that PCs and monitors enter sleep mode when not in use.
• Are disposed of responsibly. Microsoft has instituted a zero-landfill policy in the United States and is also expanding the technology reuse and recycling program globally. Microsoft's Global Procurement Group (GPG) is collaborating with Microsoft IT to ensure that technology recycling programs are in place and that employees are informed about proper disposal procedures.

Microsoft reports, "CPM has resulted in substantial savings. The more than 32 percent average energy consumption reduction per PC from FY10 to FY11, translated to an annual cost saving of $956,000 USD. There was a reduction of 10.62 million kilowatt hours (kWh), the equivalent of electricity use for 965 [1] homes for 1 year, or removing the CO2 emissions from about 2000 [2] passenger vehicles from the road for 1 year. The annual savings for FY12 are expected to exceed $1,000,000 USD and 11 million kWh."

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Full Microsoft article
Microsoft and Green ICT