The Power of Sleep – as calculated by a spreadsheet

In a previous post, I explored the power savings that can be achieved by allowing your PC to enter sleep mode after 30 minutes of inactivity. I wondered how much more energy could be saved if you actively put your PC to sleep rather than waiting for it to do so – and the answer is suprisingly good; just over 31 kWh over a working year, saving 17 kg CO2 and around £3.70 of electricity charges. Multiply that by the 8000 Windows PCs managed by iSolutions and the numbers really start to add up.

The Windows 7 PCs have a power management plan that powers down the screen after 10 minutes of inactivity and then sleeps the computer 20 minutes later. If the user actively sleeps their PC, they will save 10 mins @ 80W and 20 mins @ 30W each time. My estimated savings above assume a working day of 9.00 – 5.30 with a single one-hour meeting and a one-hour luchbreak. I developed an Excel spreadsheet that makes it simple to compare two scenarios (computer usage patterns) and calculate the annual impact of any change. The 31kWh per year represents a 17% saving, simply by putting your PC to sleep immediately rather than letting it happen automatically. The spreadsheet is available under a Creative Commons licence, so please download and use or modify it as required. PC power saving v2

iSolutions has developed a simple script that will place a ‘Sleep and Lock’ icon on the desktop of all our Windows PCs, so that a simple double-click will sleep your PC. The tricky part will be helping people to adjust their behaviour so that sleeping their PC whenever they leave their office becomes as automatic and easy as locking the door.

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