Wireless monitoring technology can be implemented by tapping into a building’s HVAC ducts, according to recent research. This can lead to both time and cost savings for builders and building managers, because the systems can be put into place without running wires throughout the building – saving money and effort.
Radio-frequency identification (RFID) systems use centralized readers to collect data from small, lightweight tags that are equipped with radio antennas. The reader broadcasts a radio wave with a specific frequency; when the RFID tag receives the transmission, it absorbs energy from that transmission, which enables it to respond to the reader by the way it reflects the wave.
“This would work with anything you can create an electronic sensor for,” explains Dan Stancil, co-author of the study paper and professor and head of North Carolina State’s Department of Electrical and Computer Engineering.
The study focused on ultrahigh-frequency (UHF) RFID systems, which typically need to be within 5-10 meters of the reader in order to respond to a transmission when placed in open spaces. However, by tapping into a building’s HVAC system, UHF RFID tags can operate when located 30 meters or more from a reader, according to the researchers.
Ductwork is a good conduit for the radio transmissions because it typically consists of hollow metal pipes that can be used to guide the radio waves, keeping the radio waves from dispersing and helping maintain a strong signal over a distance, even up to 30 meters long.
Instead of using thermometers connected to a central climate-control monitor by extensive wiring, distributed RFID tags with temperature sensors would send temperature data to readers through the ductwork by using short antennas.
“Because you can tap into existing infrastructure, I think this technology is immediately economically viable,” says Stancil. “Avoiding the labor involved with installing traditional sensors and the related wiring would likely more than compensate for the cost of the RFID tags and readers.”