Saving energy in buildings is often hampered by the lack of detailed information about what is using the energy, how much it is using, and how to automatically and remotely control devices. The problem is especially acute for the large number of small, energy-using devices that are present in both residential and commercial buildings. Most of these products use a switching ac to dc power supply to operate electronic and other internal components. We describe a “communicating power supply” (CPS) to enable the communication of energy and control information between the device and a building management system or other central entities. We developed a proof-of-concept system of Internet-connected CPSs and demonstrated both energy reporting and control utilizing a custom, cloud-based information clearing house. If CPS technology became widespread in devices, a combination of automated and human interactive solutions would enable high levels of energy savings.