Digital networks are the foundation of the information services, such as cell phones, e-mail, and the Internet, and are an expanding and indispensable part of our lives. With the wide availability of these networks, many of the devices and equipment we use in buildings increasingly depend on these networks for the functions they perform. Today, networked devices are mostly electronics, but other types of devices are gaining rich communications ability. While the information services provided by these networks are perceived almost universally to provide a net benefit to society, one drawback to these networks is that they increase energy use, both through the direct energy use of the network interfaces and equipment that comprise the network, and in the effect they have on the operating patterns of devices connected to the network. This book investigates a variety of technology and policy issues related to the energy used by digital networks to further the development of several energy efficiency technologies. Several of these technologies have since been introduced to the market, saving energy in California, the United States, and globally.