Electronics is a relatively new end-use of energy in buildings, but it is already responsible for over 10% of electricity use in buildings. Personal computers make up the largest portion of this 10%, using more than TVs and servers. More than half of PC energy use occurs when no one is present. A principal reason for this waste is that network connectivity is lost when PCs enter sleep modes. Analysis shows that active computation contributes little to annual energy use. Trace analyses reveal the depth and breadth of network activity during otherwise idle times. Today the need to maintain connections prevents many PCs from entering lower power modes. A new technology called 'proxying' was developed to preserve functionality while allowing PCs to enter very low-power, sleep modes. Proxying—now present on some new PCs–offers huge electricity savings with very low costs. The proxying technology required coordinating operating system vendors, component manufacturers, and PC companies. Proxying applies directly to other devices and will be an important strategy to reduce electricity consumption in the electronics end use.