Designing Windows 8 for virtually any device from smartphone to PC, Microsoft had a key goal in mind for all hardware platforms--energy efficiency.With laptops and mobile devices slurping up battery power and desktops and servers chewing up electricity, Microsoft wanted to ensure that any device running Windows 8 could tap into better power management. That\'s especially important since PCs, especially servers in large datacenters, typically consume a lot of energy.\"Very small changes done well in Windows can result in very large positive environmental impact because of our scale,\" Pat Stemen, a program manager on Microsoft\'s Kernel team, said in the latest Building Windows 8 blog. \"In many markets around the world, increasing electricity consumption is putting more demand on every aspect of the workplace to reduce power consumption. PCs are a significant source of potential savings.\"Software itself can impact power usage, noted Stemen, since the CPU, hard disk, memory, and other components each consume resources. The operating system and drivers also play a role since they manage the hardware.With energy savings in mind, Stemen says that Windows 8 was designed with three goals:Aim for power efficiency on all types of hardware - Whether someone is using a Windows tablet or a powerful gaming machine, the idea was to standarize on the same power management features to be consistent across all platforms.Provide great battery life - Windows 7 offered a large reduction in energy use, particularly in the battery life of mobile PCs, said Stemen, and the goal with Windows 8 was simply to maintain that same level amidst all the other feature changes.Apply the smartphone power model to PCs - Smartphones, tablets, and other mobile devices can quickly switch in and out of a low-power mode so they\'re instantly available when you need them. Microsoft\'s intent was to apply that same technique to computers running Windows 8.Looking at Windows 8 itself, Stemen said that the new OS offers three \"key innovations to improve how software influences power consumption.\" Those include the Metro style app model, idle activity, and a new device power management framework.Metro apps can potentially be running all the time, delivering news and e-mail and other updates. But Microsoft designed the Metro model so that apps run only at the right time and retreat into the background when not needed so as to consume less power. To gauge this, the new Task Manager in Windows 8 shows which specific Metro apps are suspended.