For more information on Energy-Efficient Ethernet PoE (IEEE 802.3AZ) please see the link below:
Energy-Efficient Ethernet is a set of enhancements to the twisted-pair and backplane Ethernet family of computer networking standards that allow for less power consumption during periods of low data activity. The intention was to reduce power consumption by 50% or more, while retaining full compatibility with existing equipment.
The Institute of Electrical and Electronics Engineers (IEEE), through the IEEE 802.3az task force developed the standard. The first study group had its call for interest in November 2006, and the official standards task force was authorized in May 2007.
The IEEE ratified the final standard in September 2010. Some companies introduced technology to reduce the power required for Ethernet before the standard was ratified, using the name Green Ethernet.