March 2012

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Wireless Lighting Control

  Why Lighting is the Cornerstone of Wireless Control for Commercial Buildings.
Josh Slobin
Josh Slobin,

Director Solutions Marketing,
Daintree Networks

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How many light fixtures are there in your corporate office? Even if you don’t know the exact number, you may look at your lighting energy bill and think “too many”. And how many wall switches are there? Occupancy sensors and photocells? “A lot” would be an accurate, if not precise, answer for most corporate building managers.

In fact, the sheer number of lighting devices in commercial buildings has historically been one of the roadblocks in effectively managing a building’s lighting. Still, in order to maximize energy efficiency, it must be done. After all, lighting typically accounts for up to 40% of commercial buildings’ total energy cost. Reducing this energy consumption has become a major goal for building owners, governments, utilities and many other stakeholders. But how do you manage something with so many diffuse points?

Answer: You network it. Wirelessly. Advances in wireless communications standards and energy-efficient lighting equipment have made it possible to effectively combine mesh networking with lighting control to create reliable, large-scale, vendor agnostic wireless lighting networks. The results are impressive, providing enhanced control and reductions of up to 70% in lighting energy consumption for commercial and industrial buildings. And here’s an interesting side-effect: when done right, if each of your lighting devices is a node in this mesh network, you now have a robust and pervasive infrastructure through which other components of your “intelligent building” can communicate.

The case for control

But first, why control lighting at all?

In short, lighting control systems deliver the correct amount of light, where you want it, when you want it. Lights can automatically turn on, off or dim at set times or under set conditions; facilities managers can make changes to lighting when appropriate or to meet financial incentives; and users can have control over their own lighting levels to provide optimal working conditions. Lighting control helps to reduce costs and conserve energy by turning off (or dimming) lights when they are not required.

Customers of lighting control systems often apply a set of lighting control “strategies” or applications, each of which uses a specific technology and method to control a subset of lighting usage. These strategies include occupancy sensing, daylighting, scheduling, task tuning and more.

In a networked lighting controls system, all lighting commands and settings (e.g. when and why to turn on/off/dim, sensor delays, automated strategies, associations between lights and sensors, etc.) can be accessed and changed from a centralized Web application. The data from multiple facilities or sites is merged into a single interface. So the manager of twenty retail branches can log in – from home, the office, one of the branches, etc. – and treat those branches as the single corporate entity that they are. He/she can change the lighting schedule across all branches to reflect a holiday. Or alter the off delay in the occupancy sensors in all the branches’ bathrooms, simultaneously. Or compare energy usage between window-facing offices in the five branches located in the northeast. While technologies and approaches differ, the goal is to provide control that is distributed to each light or zone, with intelligence that is centralized for ease of management.

Why wireless?

Although lighting control systems have been shown to provide tremendous benefits, many parts of the commercial building market have been reluctant to use lighting controls systems in anything but the most basic configurations due to cost and complexity of wired systems. Many of these systems have added costs due to labor, equipment and wiring. Beyond the high cost of the initial installation, the commissioning, management and upkeep of these systems has resulted in hesitation in the market. Lighting has been structured largely the same since the time of Edison, but the addition of lighting controls adds a new, unfamiliar element (control wiring) to the system.

A new generation of lighting control systems is eliminating these cost and complexity concerns, while increasing system capabilities, by removing the dedicated control wiring. Through the use of modern enterprise-class wireless networking technology, the difficult control wiring is eliminated, allowing for system-wide controls strategies without significant upgrades to existing lights or added costs.

Wireless lighting control systems offer full-featured control with added flexibility, reliability, scalability, ease of installation and use. And the cost of wiring alone is incentive for many building owners to look at wireless systems: saving installation costs, reducing copper wire use, and improving payback time.

Mesh networks

Wireless lighting systems are often organized using a “mesh” architecture. This means is that each device in the network can communicate with a controller through at least two pathways, and can relay messages for its neighbors. Data is passed through the wireless network from device to device using the most reliable communication links and most efficient path until the destination is reached.

The mesh network is self-healing, in that if any disruption occurs within the network (such as a device failing), data is automatically re-routed. Mesh networks also provide self-configuration—when a new device is added (or an existing device is moved) the network automatically works out what type of device it is (e.g. router or end device), where its neighbors are, and determines the best path through the network. After devices are configured, they regularly poll their neighbors to collect information about signal strength and possible errors, so that they can recalculate transmission routes if required. The built-in redundancy of having multiple pathways available helps to make the mesh network both robust and reliable.

Interoperability – Past, Present, and Future

[an error occurred while processing this directive] Communication is a requirement of any building controls system, lighting and otherwise - the system must be able to receive data from devices and issue commands to fixtures. Frequently the communications "language" is proprietary, created by the manufacturer of the controls system.

However, as other technology industries have repeatedly taught us in the past, the path to progress leads to the use of "open standards" for communication. In open systems, a manufacturer chooses an existing communications language that is freely available for development, and their products can communicate directly with other manufacturers' products. This way, each manufacturer can concentrate on the products in their area of expertise, rather than spending resources and effort creating and maintaining a proprietary language for their products to speak.

Such lighting controls and compatible devices exist today—and not all the compatible devices are lighting-related. For example, the popular ZigBee wireless protocol includes devices of all types, from sensors to switches to plugload devices and thermostats. This means that a ZigBee lighting controls network, designed to manage the hundreds or thousands of lighting products in a building, can also communicate with and potentially manage the non-lighting devices. This opens the door to that promise mentioned earlier: a lighting network providing the communications infrastructure for the whole smart building.

But why lighting as the core application of this network, rather than HVAC, plugload or something else? The answer lies in the numbers – and in the ceiling. Lighting may not represent the largest energy load (it’s #2), but it easily represents the greatest number of potential control points. And when it comes to building a reliable and scalable mesh network, the number of points matters. Once a wireless lighting network is in place, adding other devices and applications is simple – they piggyback on an infrastructure that’s already in place.

Of course, most building controls systems today aren’t wireless, so they don’t speak ZigBee. Many speak BACnet—another open standard. So wireless lighting controls systems that can also speak BACnet can facilitate wireless communication between devices, and share information to and from building controls systems, making the right lighting controls system far more valuable than just lighting controls. Use of open standards ensures compatibility not only with products available today, but with those standards-compliant building controls yet to be invented.

At the end of the day, controls systems that speak a common language with the components they control, and the other control systems they work with—regardless of manufacturer—are more likely to last the lifetime of your building, and continue to provide value far into the future.

About the Author

Josh Slobin brings more than 10 years of technology leadership to his position as Director of Solutions Marketing for Daintree Networks.  He is responsible for developing the company’s industry solutions, ecosystem partnerships and marketing strategy.  In addition to the cleantech industry, he has held leadership roles in wireless technology and enterprise networking both at startups and established market leaders.


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