The Pros and Cons of Wireless Lighting Control
Turning off lights when they are not needed is one of the best ways to save energy. This is especially true in commercial buildings, where lighting can account for up to 40% of the building’s total energy cost.
With wireless lighting control, you don’t need to rely on employees to turn lights on and off. Instead, you can take advantage of scheduling, timers, occupancy sensors and photosensors to deliver the optimal illumination level in all situations while minimizing wasted energy.
Many traditional building and lighting control systems are fully wired, with all lights, sensors and switches hard-wired to a central controller or gateway.
Newer lighting systems take advantage of wireless mesh networking, which allows the lights, sensors, switches and the central controller to communicate with each other without the need for wires. Removing the wires provides more flexibility in terms of where switches and sensors can be placed, and makes it more affordable to include additional sensors in the network.
Wireless mesh also supports more flexible and easier control of larger systems with more devices. It allows you to run your lighting control solution as a single system that covers an entire building (or multiple buildings), as well as room by room (or floor by floor) deployments. This provides a system-wide view of operations, current power usage, savings, and more.
So how does a wireless mesh network work?
It consists of a mesh of interconnected devices (such as luminaires, switches, and controllers). Each device contains a small radio transmitter that it uses for communication. The transmitters can be built in to the device or can be fitted externally.
In a wireless mesh network, each device is typically connected through at least two pathways, and can relay messages for its neighbors.
Data is passed through the network from device to device using the most reliable communication links and most efficient path until the destination is reached. Two-way communication also helps to increase reliability, by allowing devices to acknowledge receipt of data and to require retransmission of data not received.
The mesh network is self-healing, in that if any disruption occurs within the network (such as a device failing or being removed), data is automatically re-routed. The built-in redundancy of having multiple pathways available helps to make the mesh network both robust and reliable.
Mesh networks are also highly scalable, in that you can extend the network simply by adding more devices. The network’s self-configuring capabilities identify when a device is added: working out what type of device it is, where its neighbors are, and what the best path is through the network. Weak signals and dead zones can also be eliminated simply by adding more devices to the network.
Pros and cons
While mesh networks provide many benefits for lighting control, and removing the wires provides even more including increased flexibility and reduced installation costs. But no single solution is perfect for everyone. Below is a summary of both the pros and cons of wireless mesh lighting control:
- Cost: Installation costs are greatly reduced without the need to run control wires from each device back to the central controller. However, wireless sensors and controls are sometimes more expensive than their wired counterparts, so some of the money you save on wiring may go back into purchasing the wireless devices.
- Security: Both wired and wireless solutions provide effective security. Most wireless lighting technologies use 128-bit Advanced Encryption Standard (AES) security for communications. This security is robust enough that, in June 2003, the US Government announced that AES may be used to protect classified information.
- Scalability: Wireless mesh solutions support more devices over greater distances than wired ones, which makes wireless ideal for multi-office and multi-floor installations. The nature of mesh networks means that simply adding new devices can extend the communication coverage of the network. And the wireless nature of the controls allows you to place them in areas that were previously difficult or costly to access.
- Reliability: Both wired and wireless networks use mature technologies that offer great robustness and reliability. There is the potential of radio interference and data loss with some wireless technologies that share the same radio frequency (such as Wi-Fi® and ZigBee®). Fortunately, this problem is easily avoided for your lighting solution by selecting channels within the radio frequency that are not commonly used by other wireless devices. You can further protect yourself by selecting a wireless mesh technology like ZigBee, which can automatically switch to a new channel if it detects interference on the current channel.
- Flexibility: This is one of the biggest benefits of wireless. Devices can be installed where they will provide maximum benefit instead of where it is easiest to run wires. Devices are also grouped into “zones” using addressing and software rather than hard wiring, which allows changes to be made at any time through simple software reconfiguration (no costly or disruptive rewiring required).
- Complexity: Wireless allows you to avoid the complexity of connecting wires from hundreds (or thousands) of devices back to a controller, but that comes at a price. It can be more difficult to locate a device when you don’t have wires to follow. The good news is that tools are available to help you locate and identify devices during installation and commissioning, and for the ongoing operation, monitoring and maintenance of the system.
Source: Gail Hodgson