RFID technology can leverage HVAC systems for communicating tag information to readers.
This can enable the deployment of intelligent sensors throughout a building and minimize the amount of wiring required to support communications. …
… “However, the researchers have found that, by employing a building’s HVAC system, UHF RFID tags can operate when located 100 feet or more from a reader.
The HVAC ductwork is an excellent conduit for the radio transmissions … “ …
via MSNBC: Tiny radio antennas.
Dr. Dan Stancil, NC State, Research Program.
RFIDa: RFID Technology is an internet destination dedicated to documenting the application of radio frequency identification technologies. 
