One of the biggest energy hogs at work or in your home office is your desktop computer. When buying a new computer, a laptop is more energy-efficient than a desktop. But for practicality, sometimes a desktop is the only choice that can work. One way to reduce the energy usage of a desktop computer is to be selective about the monitor size. By choosing a screen and then going down 2 inches, you reduce the energy consumption of the monitor by 30 percent. That's just one easy step to save energy -- and you'll hardly notice a difference.