Digital networks are the foundation of the information services, and play an expanding and indispensable role in our lives, via the Internet, email, mobile phones, etc. However, these networks consume energy, 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. The purpose of this research was to investigate a variety of technology and policy issues related to the energy use caused by digital networks, and to further develop several energy-efficiency technologies targeted at networks. Improving network energy efficiency often requires addressing not just one device but the network as a whole. For this reason, much of the project research conducted focused on influencing the standard protocols and applications that define the network: • Working with the Institute of Electrical and Electronic Engineers, this project supported creation of a new technology standard, IEEE 802.3az ("Energy Efficient Ethernet") to enable most Ethernet link technologies to save energy when lightly used, which is most of the time for most interfaces. • In partnership with the University of South Florida, Intel Corporation, and others, researchers developed the network connectivity proxying concept. The team then worked with the Ecma International standards organization, and its many member companies, to create a technology standard for network proxying. • Network connections are a significant driver of set-top box energy use, and network presence proxying is an important technology to reduce this energy use. The project demonstrated that targeted investment in research and technology on networks by the energy efficiency community can result in considerable energy savings. The project findings can be applied to help California meet its energy goals in the coming decades, and also to reduce energy use both nationally and globally.