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Many building owners today are dealing with higher utility bills, old equipment systems and disparate controls that have been pieced together. One solution is the use of wireless networks to cost-effectively upgrade and replace antiquated controls.
In commercial properties and institutions, such as schools, hospitals, museums, historic buildings, large retail spaces and constantly changing office layouts, wireless has proven to be an efficient solution that can be integrated with minimal disruption to daily operations and used to optimize building automation system communication. This provides the ability to communicate with any controller via a wireless connection.
With the proper set-up and implementation, wireless can be just as effective as a wired network. In fact, wireless has distinct advantages over wired networks. The cost of wireless devices continues to decrease, making them an affordable option. Once implemented, they help increase maintenance team productivity and optimize energy efficiency.
If it makes financial sense, why aren’t more building owners and managers taking advantage of wireless? Understanding the differences between the types of wireless networks available might make the decision less daunting.
Point-to-point, point-to-multi-point and mesh networks
The major types of wireless control networks are point-to-point, in which all signals are transmitted between two devices; point-to-multi-point, where multiple devices communicate through a central point (e.g., Wi-Fi, EnOcean) with each point being a point-to-point link; and mesh, in which all routers communicate directly with each other (e.g., ZigBee). With point-to-point, the signal can get blocked. That is why mesh technology has become the standard for network reliability.
Mesh networks distribute intelligence to access points by incorporating a grid-like topology. A mesh network allows nodes or access points to communicate with other nodes without being routed through a central switch point, eliminating centralized failure, and providing an advanced self-learning, self-healing, self-addressing option. A signal will “multihop” among its different nodes to circumvent obstructions as it seeks and ultimately finds its target node. These redundant communication paths provide a reliable route for communication – even proving to be an effective technology in buildings containing challenging obstructions.
Uses of these wireless technologies vary based on the requirements of the project. Is the building owner looking for a solution capable of supporting controller networks or just simple sensing devices? Does proprietary technology or open availability matter? Would knowing that products have been tested and certified bring greater peace-of-mind to installers and end-customers? There are options available when selecting a wireless network that are based on the application and needs of the building.
ZigBee is a standard for mesh technology that can be used for controllers and sensors. ZigBee low-power wireless mesh networking and sensing technology is based on IEEE 802.15.4 and created and controlled by an open alliance of organizations. It is the only BACnet approved wireless mesh network standard for commercial buildings, defining and ensuring interoperability through product testing and certification.
Speed and reliability
Speed and reliability are the most discussed topics when considering the use of a wireless solution. As consumers, we want great speed and performance. Wireless environments are dynamic and subject to change, yet, they can be as fast as any wired network.
Speed is a tough concept to explain briefly. Basically, the speed (or more importantly, throughput) of a wireless network is based on the frequency and the performance of the radio. The higher the frequency, the faster the speed and payload it can carry. With wired networks, speed is a factor associated with data rates, the physical network and the efficiency of the protocol.
There are tradeoffs, however, that come with the higher frequencies. Signals transmitted at higher frequencies are more susceptible to absorption by building materials than lower frequencies and this can impact communication. As mentioned, speed is also affected by the efficiency of the protocol on which the messages are carried through the air. The protocol needs to be efficient at getting messages from point A to B but also deal with any interruptions along the way.
Mesh networks have the advantage over point-to-point configurations because the network automatically handles re-routing should an obstruction appear or a node go offline. This is one of the reasons why mesh is more reliable.
Radio power also affects communication strength. The transceiver must have enough power to communicate to the receiver while overcoming noise, free space loss and building obstructions. Since the power levels of wireless devices are government regulated, their range can vary, but they are typically able to communicate effectively within a range of a few hundred feet, depending on obstructions. Building materials, structures, and movement within a facility impact all of this.
Installation and maintenance
Among its benefits, wireless technology can reduce construction costs by eliminating time and material costs associated with running cable or wiring (and conduit if required) over long distances in new and retrofit control projects.
With wireless networks, the operative word is flexibility. HVAC specialists can simply place sensors where they will provide the most accurate inputs for the ambient conditions of the space – instead of wired to a wall that is bathed in sunlight all morning or in a shadow all afternoon. As space configurations change, the sensor is simply moved to a new position, ensuring the accurate input required to achieve sophisticated and optimized control.
With tools and applications that work in conjunction with a laptop, smartphone, or tablet, engineers or technicians can monitor, access and troubleshoot any controller on the network from anywhere at any time. This substantially reduces the time maintenance teams lost traveling to each controller to diagnose, access and service the controller. With wireless networks, more square footage can be serviced with fewer people.
Wireless technology helps to reduce the drain on scarce resources, such as copper. More wireless and less copper means less waste, less in our landfills, and less strain on the environment. Wireless can also contribute toward satisfying credits in the categories of Sustainable Sites, Energy and Atmosphere, and Indoor Environmental Quality under the U.S. Green Building Council’s LEED green building certification program.
As more buildings are being retrofitted to meet sustainability goals and LEED standards, wireless networks are becoming relied upon to create smarter buildings by gathering and monitoring information and creating open communication environments. Wireless enables the placement of sensors where ever they are needed to gain tight control. This has impacted energy efficiency at many installations, reducing wasted lighting and heating expenditure by 50% in many cases.
Jay Hendrix is a member of the ZigBee Alliance and a product line manager for Siemens Industry Inc.