Official Google Blog: “Here’s a suggestion for everyone to save energy over the holidays (and at other times!): turn off your computer and monitor or put them into “sleep” mode when you’re not using them. Why? The typical desktop PC uses 100-200 watts even when it’s idle. That’s the equivalent of 1-2 bright incandescent (read: inefficient) light bulbs. (Note: new PCs that comply with the latest Energy Star specifications consume less than 50-60 watts when idle.) You wouldn’t leave your car running for hours when it’s just sitting there. Most of us wouldn’t leave a bright light bulb burning for hours when no one is nearby to need the light. So why leave your computer on? If you’re leaving your office for the holidays, turn off your PC. If it consumes 100 watts, that will save 2.4 kWh/day, or over 25 kWh for the next 11 days through January 1st. In California, that will stop about 40 kg of CO2 from being put into the air, and save about $2.50. For every 1 million people who do this, that will stop 40,000 tonnes (metric tons) of CO2 from being emitted, and save $2.5 million. In many areas, it will reduce emissions even further, and save even more money. The same issue applies at home: turn off your computer or put it to sleep when you’re not using it. The automatic power management settings on most computers will put them to sleep automatically after a specified idle period.”