By Naomi Millán, Senior Editor
Building Automation Article Use Policy
The key to reliability in a wireless system is correct installation and commissioning, says Kessler. If these don't occur, the system won't work as expected and the facility manager is likely to set the system on override, he says.
To work properly, there has to be appropriate signal strength and coverage. The system has to be designed so that there is no interference between system components, such as between the thermostat and the zone box, or the occupancy sensor and the light switch, for example, says Szcodronski.
The first step is to have a wireless site survey performed, Szcodronski says. In this process, the facility's floor plans are imported into a 3-D modeling system that helps map the materials present in the facility and illustrate how signals are penetrating walls and into rooms, he says. The program also simulates traffic, so facility managers can be assured the multiple wireless controls devices they're planning for a space will have enough bandwidth and will not interfere with each other.
It is important as well to involve IT early on in the design process. "Anytime you want to put a new system in the building, the IT group doesn't like it," says Kessler. "It's an unknown." To prevent problems, it's important to get in front of IT at the beginning and explain. "If you get in there late, and you're trying to rush something, they usually throw up their hands and it creates a big delay. The key is to educate them and ask them what they need early."
Experts say to follow standards to safeguard reliability. "Have a manufacturer look over your shoulder," says Babigian.
Also, don't cheat the system by being cheap. A big appeal of wireless controls and systems is the upfront cost savings at installation. But the success of the system depends on having sufficient and robust coverage, so additional repeaters might be needed. "Make sure there are enough hubs out there," says Flanagan. "If the signal can't get to you, you can't get use or benefit from the signal. A lot of companies want to skimp on the wireless devices that transmit the signal and receive the signal. That's great for saving money, but you're limiting the system."
In addition, make sure not to create inadvertent dead zones. One benefit of wireless is that sensors can be easily relocated as needed. Care has to be taken, however, that the sensor is not moved out of range, corrupting the communication pathway. For example, some wireless systems employ a "mesh network," basically overlapping transmission fields so that sensors can reroute a signal if their primary communication path is blocked. The self-healing nature of this setup depends on sensors remaining in range as designed.
With devices that can frequency hop, signal cancellation through interference is not very likely in a well-designed system, say experts. But knowing the frequencies in use in a facility is still an important step. Most sensors for facility management purposes are talking on proprietary frequencies, but some use a frequency similar to WiFi, which has two spectrums: 2.4 GHz and 5 GHz. "Recently, almost all new devices have the ability to talk to 5 GHz, which alleviates the interference," says Szcodronski. "You should always know what frequency the protocol is using and make sure there is no interference with mission critical systems."
If wireless is not quite ready for prime time at your facility, get ready because that time will come soon enough. "It's the wave of the future," says Isenberg. "Everything is going to be wireless before we know it."
Popularity And Benefits Of Wireless Systems And Sensors Are Growing
Wireless Saves Labor Costs But Raises Security And Reliability Issues
Wireless Best Practices Start With Correct Installation And Commissioning