Wireless Building Controls- Part 1: Security and Reliability of Wireless BA
February 01, 2010
By Lacey Muszynski, Assistant Editor
Appeared in Building Operating Management/FacilitiesNet
As the popularity of PDAs and iPhones continues to soar, people are becoming more and more accustomed to having information at their fingertips wirelessly. Couple that with the growing number of homes equipped with wireless controls for everything from window blinds to surround sound, and people start expecting that level of wireless control everywhere. Top executives are starting to ask, if I can have it at home, why can't I have wireless control in my facility?
That's the top-down push many facility managers are encountering, prompting a look into wireless building automation and lighting controls, says Josh Thompson, principal, PointSource. In the past, wireless controls may not have been considered because of the perception that wireless was still a little too sci-fi, says Dawn MacFadyen, associate partner and electrical engineer with Syska Hennessy Group. Now, facility managers are warming up to the idea.
Wireless building products are giving facility managers more choices for saving energy costs. A wireless approach may make it easier to justify the investment in BAS or lighting controls because wireless systems don't typically cost as much to install as wired systems. They also offer flexibility, says MacFadyen.
"In lighting controls systems, you can change the zoning easily because there's no control wiring," she says. "Changes in space planning are easier to accommodate."
Keep in Mind
The benefits of wireless control systems are numerous, but there are some things to keep in mind before implementing one. Here are some of the questions facility managers might be asked before going wireless.
Isn't wireless easy to hack? Contrary to popular belief, a wireless network may be more secure than a hardwired network, says Peter O'Connor, principal, RTKL. That is especially true in facilities like hospitals that offer Wi-Fi access to the public. On a wired network, it is more difficult to tell who is plugging into a network jack. "Is it a family laptop? Is it medical equipment? For visitor access, a public network can be created where there's a login required that identifies public users," O'Connor says. That allows facility managers to dedicate one wireless network to public access or to segment one network to keep the clinical or BAS networks secure.
The vast majority of wireless networks are spectrum hopping, says Thompson. That means they're never on one channel long enough to interfere with anything or get imposed upon. Plus, in a wireless mesh network, pertinent building information is difficult to collect if someone tries to hack into the network. "If you hack into it, you only get tiny amounts of data that are fairly random in nature," says Thompson. "You'd need to know exactly what devices you're listening to and then decrypt the information on top of it."
Will the network ever go down? Reliability isn't as much of a concern now as it was in the past, says MacFadyen. That's because most wireless networks are designed to be mesh networks. In the past, networks were designed like a star, with a receiver in the middle and devices around it, she says. If one of the devices stopped working, then the whole system went down. But a mesh network is designed so that each device can send and receive data from any number of other devices. If a device stops working, it's simply ignored. This also makes it easier to locate devices that may not be working properly.
There are still instances where unforeseen circumstances may interrupt wireless networks. Thompson refers to this as the "trucker syndrome." "You cannot control every interaction with the outside world," he says. "So if a trucker happens to drive under your building, his CB radio might interfere with the wireless network, for example."
Random unforeseen events that might disrupt the network are more likely to occur in densely populated areas like Manhattan or near a military base, Thompson says. Even in large campus environments, something as simple as an old microwave might interfere with the network. Unfortunately, not every situation can be planned for, so facility managers will need to solve problems as they happen.
What if we want to add more controls later? Being able to expand a wireless BAS in the future is often a door facility managers want to leave open. Facility managers should be aware that many manufacturers use proprietary languages to send wireless signals, says MacFadyen. That means they can only guarantee that their own products will work with their system. The systems work well, she says, but facility managers should recognize that only products from that manufacturer can be used in the future.
Some wireless building automation devices use a language called ZigBee, which is based on IEEE standard 802.15.4-2003. The use of that communications protocol enables building automation companies to develop interoperable products.