The pros and cons of networked wireless lighting
Wireless lighting controls offer many benefits. Lighting designers should be aware of these advantages, and take note of any drawbacks.
- Know how to communicate the client’s expectations for the lighting control system to the manufacturer to ensure that the client’s anticipated functionality is fully realized in the finished spaces.
- Be aware of security considerations and the importance of getting the information technology administrator involved early in the design process.
- Learn what to look for and look out for when reviewing shop drawings and equipment submittals.
Commercial wireless systems currently on the market echo the benefits of smart home lighting techniques. Using a sleek and, most importantly, user-friendly app for controls, they are flexible and scalable and advertised by manufacturers as “so easy, even your teenager could use them.”
Chris McRae, a lighting control expert at Gasser Bush Associates said, “The biggest benefit to adding wireless controls is that they provide features for the clients that aren’t possible with wired systems, such as easily configured daylighting, adjustable dimming parameters and retrofitting into existing locations. As energy codes continue their evolution, requiring more and more from lighting controls, wireless systems are becoming a more viable option for counteracting the cost impact for clients.”
To reiterate McRae’s statement, wired applications typically are not conducive to routing new wiring and concealing new devices to adapt to evolving lighting solutions.
Wired versus wireless
Traditional wired lighting control systems consist of an input device such as a photocell or occupancy sensors that observe conditions in a space and communicate back through dedicated low-voltage wiring to a power controller. The power controller then manipulates the output of the luminaires based on the input of the sensors. Once placed, these hardwired sensors and wall switches are pretty much locked into place. The grouping of fixtures that a sensor or switch operates is not easily modifiable.
Wireless systems operate similarly, but instead of having a hardwired low-voltage connection between the input device and the power controller, a radio signal provides that connection. The controller also may be connected wirelessly to a remote power pack that provides dimming or switching direction to a group of luminaires. Beyond the line-voltage wiring required in both wired and wireless system, wireless systems are not truly wireless if there are still low-voltage control wires between luminaires back to the controlling power pack. Sensor or switch locations can be changed fairly easily, but fixture groupings can be difficult to update or modify. Lighting designers should consider wireless open protocols. Otherwise, an owner could be locked in to a manufacturer’s product line.
Some fixture manufacturers are beginning to bundle wireless sensors into their fixtures, further simplifying specification, installation and commissioning. Integrating photocells and occupancy sensors on each fixture takes lighting control to an even more granular level for additional user personalization and energy savings.
For example, wireless sensors can communicate back to the lighting control system for monitoring. Some of these systems also claim that health of fixtures can be remotely monitored and in some cases fixtures themselves can request maintenance if they are operating in a suboptimal way. Manufacturers also are touting the value–added features of sensors integrated with fixtures, such as space–use monitoring. Though having photocell and occupancy sensors integrated into every fixture does increase the cost of fixtures, many manufacturers are defaulting to including them — or at least the capacity for them Manufacturers seem to be betting that this cost will be offset by reduced labor and equipment savings by eliminating the need for low-voltage control wiring connecting fixtures to the control system or standalone sensors.
Depending on the complexity of the system, either wired or wireless approaches may use a server or gateway to monitor and report energy usage or facilitate control and coordination over many spaces. Wired and wireless systems are capable of controlling spaces from one room up to an entire high-rise office tower and beyond. Wireless control systems will, not unlike their predecessors, will default to 100 percent on for all lighting, if a loss of network or power to the building occurs.
There are a few notable advantages of wireless control adoption, namely lower installation costs, flexibility and scalability. With fewer wires to run and potentially less conduit required, material and labor savings are a benefit of wireless. Unless construction is extensive, retrofitting a wired system into an existing structure can be challenging. With a large space, a wired system might require so much cabling that it becomes prohibitively expensive. Wireless sensors and control stations allow for equipment placement where it would otherwise be difficult or impossible to place due to accessibility or distance limitations. As the use of a space changes over time, moving a wireless sensor or control station is much easier and less intrusive than it would be with a wired system. In addition, adding square footage or control zones to a wireless system is a relatively simple task.
“Wireless control eliminates the need for dedicated control wiring and associated switch legs, traveler wires, conduit in many cases and other raw materials, speeding up and simplifying installation. With no damage to walls or ceilings and little to no disruption to business operations, wireless control lends itself well to installing even sophisticated control systems in existing buildings and applications like street lighting,” said Craig DiLouie in the article, “Introduction to Wireless Lighting Controls,” published by the Lighting Controls Association.
Retrofit spaces, tasked with becoming compliant with the requirements in ASHRAE Standard 90.1-2013: Energy Standard for Buildings Except Low-Rise Residential Buildings, require more control (occupancy, daylight sensing, etc.) than they did previously, motivating a technology evaluation often favoring wireless lighting control over installing a new wired network. Whether these projected installations savings find their way back to the customer is another matter. An installing contractor unfamiliar with these new wireless systems may mean they bid them incorrectly to protect themselves from the learning curve of the new technology.
Figure 1: The direct-indirect LED pendants are arranged in a visually interesting pattern, breaking up the monotony of the continuous pendants and reduced energy usage to 0.34 watts per square foot. Courtesy: Illuminart
The cost-savings found in installing a wireless over a wired lighting control system are easily quantifiable and are a frequent selling point for manufacturers. Manufacturers also love to discuss the other virtues of a wireless system, especially when deployed as a networked system. Glossy brochures are compelling in touting the savings and benefits of a networked application, with their overall message often resonating with a client’s facilities manager or accounting department. Typically, less enthralled though, are the client’s information technology administrators who, after studying the risks of a networked system, see yet another opportunity for a cybersecurity attack vector, in exchange for the novelty and convenience of being able to log and analyze energy consumption.
We asked our lighting control friends about security. “This is a topic that many clients do not put enough emphasis on, and I blame Alexa,” said McRae. “With the advent of home control systems, people often ask ‘if I can do ‘x’ at home, why not in an office environment?’ My response is that the stakes are much higher in the office where much more ancillary data is at risk, than in an individual residence. When implementing wireless control systems in commercial spaces, much greater care must be given to ensure the integrity of the lighting and building networks. While the temptation to use off-the-shelf Wi-Fi technologies may be high since these are quickly set up and are fairly low cost, clients must take a careful approach and consider systems with multiple levels of security to prevent unauthorized access. This is particularly important with lighting control systems that are integrated into the building networks, where cross-contamination is possible if not done properly.”
Adam Gouda, former controls manager at Clarus Lighting & Controls acknowledges the risk as well, calling it paramount to the discussion on wireless lighting control with clients. He advocates for a more robust standard and certification process,
“We want to see NIST certification and Department of Defense approval using 128–bit advanced encryption standard — minimum. We also want to see DesignLights Consortium certification for advanced lighting control,” he said. “Additionally, this is where we need to bring IT and electrical together to collaborate and ensure that project planning and execution are seamless. Perhaps widespread interoperability, encryption and standards for the sake of evaluating the value proposition is the next best step.”
IT personnel can weigh in on the feasibility of a dedicated server or space within an existing server to accommodate lighting controls and provide risk management expectations. Further, it’s important for IT to discuss with the lighting controls manufacturer the level of administrative control. Unfortunately, some systems allow for only one definition of administrator, giving too much control to support administrators who may assist with room definition or light levels, but should not be given the same level of control more qualified operators.
Power over Ethernet
Beyond bundling fixtures with wireless sensors, more manufacturers also are developing Power over Ethernet lighting solutions, which use commonly available Cat 5 or Cat 6 cabling, effectively combining control and power wiring for fixtures into one cable. Pushed by ever–increasing energy code requirements, these systems offer granular level control down to the individual luminaire, which for the end user can offer ultimate customization of a space.
With programming that may be carried out on a tablet, control zones can be set up and changed on the fly while walking the space being commissioned. Some fixtures are available with onboard sensors installed at the factory, making standalone photocells or occupancy sensors unnecessary. Those leery of wireless systems can take some measure of comfort in the physical connection of the low-voltage wiring that ties all fixtures back to the network switch and upstream from there to the user interface. This also can be advantageous where concerns about radio interference are a determining factor, such as hospitals and test facilities.
Key selling features of currently available PoE systems include user–friendly controls and customization, which appeal to end users, and simplified code compliance, which appeals to designers and specifiers. Much of the planning and execution for a lighting control system shifts from the design phases to the commissioning and occupancy phases, potentially negating the challenges of last–minute changes, which happens more often than not. The simplicity of only needing one cable type to control and power fixtures should take some of the guesswork out of the bidding process.
In systems that include sensors integrated into every fixture, facilities management and planning can benefit from space–use optimization and maintenance scheduling based on heat–mapping of occupants throughout the day. Additional energy savings can be found from sharing the data collected from the fixtures with the HVAC systems to automatically adjust the thermostat for times that have been observed to be low–demand. In time, patterns and insights identified by the ubiquitous network of fixtures and the overarching lighting control system will surely grow, with economic benefits to follow.
While there are inherent benefits, PoE systems are not without their drawbacks. The limited amperage of these low-voltage systems mean that relatively few fixtures can be powered by a network switch. An open–office environment with hundreds of PoE luminaires may require dozens of the network switches that provide the power. The network switches can be distributed around the office; they still need to be accessible and finding space for them often presents a coordination challenge.
Because these are low-voltage systems, installation is opened up to more than just a licensed electrician that has installed traditional lighting systems. It may decrease the cost of labor, but will the quality of the installation meet expectations because fewer tidy runs of conduit will be necessary? Our experience is that very few thoroughly trained electricians are trained in making the low-voltage terminations that wireless systems require. Who is trained to install low-voltage PoE lighting systems? In our opinion and based on our experience, low-voltage contractors could easily step into this market. However, it is also possible that IT professionals could be asked to become lighting equipment installers. However not all IT administrators will be eager to add the title of “lighting administrator” to their already full plate of responsibilities.
Figure 2: After the renovation, the lighting control system enabled dimming, increased use of occupancy sensors, daylight harvesting and a master time-clock. Courtesy: Illuminart
Designing for the end user
As lighting specifiers, these are exciting times as we pay witness to the development of innovative lighting controls in real time. On a daily basis, our designers work with lighting control system designers and manufacturers on a daily basis. Every quarter, manufacturers roll out a new fixtures or lighting control system equipment that responds to the increased demands of codes and provides more features for the end user. Sometimes we see a new feature that makes a lot of sense and we can imagine its application, while other features make us scratch our heads and wonder what the product development team was thinking.
As designers, we ask a lot of questions and are often left with unsatisfactory answers. For example, “How does an incandescent decorative fixture integrate with your system? Your system is proprietary. Therefore can a fixture from another manufacturer get bridged into your system? I can use a smartphone app with your system, but how do I control my lights if you stop supporting the app and it becomes incompatible with a future version of iOS?"
Ultimately, it’s the end user that we design for and it’s important for us to listen to them and understand what they really need as opposed to what they want. It’s the lighting designer’s responsibility to help guide them toward a lighting control system that meets their expectations without overselling them on features that are innovative but ultimately unsuitable for their space.
Things to keep in mind when considering networked lighting control:
- How important is scalability to you? Are you planning any expansion in the future?
- What do you expect from an interface?
- How much do you want to be able to adjust your lighting without calling a technical expert?
- Have you spoken to your IT group about the pros and cons of networked lighting?
- What integration do you expect with other building systems, like HVAC and audiovisual?
- How do you integrate fixtures from other manufacturers into a proprietary system?Do you know which devices in a proposed wireless system are truly wireless versus wired (Cat 5, line voltage, etc.), and where they can be located? If not, ask for a cable legend and a schematic to help guide your decisions.