On one side is General Electric, which argues that ZigBee is more energy efficient than Wi-Fi. On the other side, the Wi-Fi Alliance maintains that "Wi-Fi offers unsurpassed capabilities for the smart grid" and that GE's recent study hailing ZigBee "is flawed, resulting in inaccurate findings." The Wi-Fi Alliance on Monday released its rejoinder to GE's early December white paper.
In its report, a team of GE engineers and technicians from the appliances and lighting units studied Wi-Fi, Bluetooth, and ZigBee solutions to determine which of the existing technologies would best minimize the energy impact of home energy networks. The GE team dismissed Bluetooth quickly, arguing that its limited range made it unsuitable for home networking of appliances and other products.
In comparing Wi-Fi with ZigBee, GE said it found that components for ZigBee-based devices were less expensive than Wi-Fi components. In addition, the GE investigators said ZigBee's mesh networking capability resulted in energy savings as did other features of the ZigBee standard.
The GE team argued that overall home network energy cost savings for ZigBee over Wi-Fi would result in theoretical annual savings of $315 million based on an assumed population of 750 million devices.
In its release rebutting the GE findings, the Wi-Fi Alliance said the GE investigators based their findings in part on older, less efficient Wi-Fi technology that has been upgraded since the GE report was issued.
"Because the evaluation was based on old technologies," said the Wi-Fi Alliance, "its conclusions present an inaccurate characterization of the energy efficiency of both ZigBee and Wi-Fi technologies and cannot be used to draw generalized conclusions about the state of smart grid communications technology today."
The Wi-Fi Alliance noted that more recent Wi-Fi releases, including 802.11n, are more energy-efficient than the older Wi-Fi technology examined by the GE team.