Lighting

What to know about wireless lighting systems

As more lighting devices, systems and services become connected wirelessly, so have lighting control systems, offering flexibility and scalability

By Timothy Larson April 21, 2021
Courtesy: RTM Engineering Consultants

 

Learning Objectives

  • Learn about the basic elements of wireless lighting systems.
  • Consider the design considerations and best practices.
  • Look at the future of lighting systems.

Wireless lighting systems are made up of physical devices, both wired and wireless, and a communications network that securely collects data and controls the system. The light fixtures themselves are still hard-wired for power, but how and when they turn on/off and what information they gather is all done wirelessly.

The basic architecture of a networked lighting system consists of light fixtures, switches, sensors, controllers, gateways and software that controls the entire system (see Figure 4). In a typical system, all of these devices are wired together and communicate over a common protocol.

In a wireless system, the light fixtures, controllers, gateways and sometimes switches are still hard-wired to a power source. The data collection (sensors) and controls (switches and sensors) typically communicate wirelessly.

Physical wireless lighting devices

Light fixtures for wireless systems are often already enabled with integral wireless controllers and sensors directly from the manufacturer, or can be provided with a third-party wireless controller and sensor. In both cases, the light fixtures have wired power directly fed to them via the wireless controllers. When the wireless controllers receive a signal, they may switch the power on/off, dim and/or change color temperature, depending on the function and capabilities of the system devices.

Figure 1: Specifying equipment for an emerging technology within any building, especially a 100,000-square-foot health care facility, can have its challenges. As the engineering consultant for the project, keeping communication channels open between owner and manufacturer is imperative. Working through any issues with a reputable manufacturer can help alleviate problems that arise and ensure a successful project for the owner. Courtesy: RTM Engineering Consultants

Figure 1: Specifying equipment for an emerging technology within any building, especially a 100,000-square-foot health care facility, can have its challenges. As the engineering consultant for the project, keeping communication channels open between owner and manufacturer is imperative. Working through any issues with a reputable manufacturer can help alleviate problems that arise and ensure a successful project for the owner. Courtesy: RTM Engineering Consultants

Switches for wireless systems come in a few varieties — hard-wired for power, battery or batteryless (using kinetic energy from the switch action). The switches communicate with the wireless network to control the light fixtures they are programmed with and can provide simple on/off control, dimming or multiple scenes, depending on the manufacturer. Switches hard-wired for power can use line voltage or low-voltage power. Because these switches require a hard-wired feed, they require a wall rough-in location. The battery or batteryless switches do not need a wall rough-in and can be simply mounted using drywall screws or mounting tape.

Smart sensors collect data from the environment (occupancy/vacancy, daylighting, temperature, etc.) and can often communicate with other Bluetooth-enabled devices. Sensors can be integrated directly into the light fixture or as a standalone unit, as noted above. When fixture-mounted, the sensor is powered via the light fixture. Having sensors mounted in each fixture increases the granularity of the data collected, which increases the potential value of the system. Sensors with Bluetooth capability can communicate with low-energy Bluetooth devices such as asset tags or badges for real-time locating systems.

Wireless controllers are located on or near the light fixture and communicate with the switches and sensors to provide on/off and/or dimming control of the fixture. Instead of having to run wires out to a physical device, these switches or dimmers are mounted on the fixture itself. Besides controlling the fixture, the controller often can be specified to collect real-time energy usage of the fixture to send back to the system.

Wireless area controller devices (gateways) are centrally located, collect data from an area of the mesh network and send that data into the system’s main server. To ensure a solid and reliable network, wireless area controllers are placed to cover a floor or a maximum square footage area. The wireless area controllers are then hard-wired back into the system’s main server.

Most systems have their own proprietary software, which runs the lighting control system. In these cases, the smart sensors, switches and controllers will only function on the manufacturer’s software platform. Not as common (but still available) are wireless controllers, sensors and switches that allow third-party control systems, like building automation systems, to communicate and directly control the wireless devices without a proprietary system from the lighting vendor.

Figure 2: This wirelessly controlled light fixture has an integral occupancy sensor. Courtesy: RTM Engineering Consultants

Figure 2: This wirelessly controlled light fixture has an integral occupancy sensor. Courtesy: RTM Engineering Consultants

Communications network for lighting

There are several different network topologies and many different protocols available to create a communications network. The ones that will be discussed here are the most common versions that have emerged for wireless lighting systems.

These topologies are generally categorized into linear and mesh. Linear topologies transmit messages from one device to another in a sequential order. The bus, star and tree topologies are examples of linear topologies. Comparatively, on a bus network, every device is connected to a central trunk or backbone, the star network has every device connected directly back to the main controller and the tree is a combination of the two consisting of a series of star networks connected via a linear trunk.

The mesh network has no predefined communications path in the system. All devices communicate with each other, receiving and transmitting the messages until received by an area controller. This network of data travels on multiple paths, which creates the mesh structure and makes the system inherently more reliable (including coverage of areas that have potential signal barriers). These multiple paths also mean signals can travel very fast in the network, thus reducing any latency issues between the user and the control output.

Due to their structure, linear systems have single points of failure and do not have multiple paths available to cover areas that have signal obstructions. Mesh can reroute and is essentially self-healing; if one device fails the signal will automatically reroute around the failed device.

The protocol for communication on the wireless system identifies how the devices speak to each other, the language of the system. This can be open protocol or proprietary. Proprietary is typically a system developed by a manufacturer that is only compatible with its own system. Open protocol is a system that has been developed to be the standard of an industry with many manufacturers producing devices that use the same protocol.

The wireless communication standard that is most widely used today is IEEE 802.15.4: IEEE Standard for Low-Rate Wireless Networks. The IEEE 802.15.4 standard has been developed for low data rate monitor and control applications that need extended battery life, low power consumption and longer-range communications. Using an open protocol such as the IEEE 802.15.4 standard allows the system to use components or systems from multiple manufacturers and allows for greater future flexibility and changes. The standard operates at 800 megahertz, 900 megahertz or 2.4 gigahertz. Systems that operate at the lower frequencies have longer range, better obstruction penetration and fewer latency issues.

Figure 3: A wireless switch is powered by the kinetic energy generated when users push the switch. Courtesy: RTM Engineering Consultants

Figure 3: A wireless switch is powered by the kinetic energy generated when users push the switch. Courtesy: RTM Engineering Consultants

Wireless lighting design considerations

When LEDs became more prominent commercial lighting options, manufacturers began developing all kinds of LED light fixtures without any manufacturing or testing standards. This scenario can be compared to present-day emerging wireless lighting technology. As with any new technology, engineering consultants should carefully research technologies and take the time to investigate products and manufacturers before specifying them on projects. By gathering as much information and evidence as possible, engineers can ensure the system being specified will work.

Looking to established manufacturers for this technology is one way to make sure that, if something does go wrong, the company will back up its product (and still be in business) before the warranty expires. Another method can be to install a similar system on a smaller scale, either in your office or in the client’s building, so firsthand information can be gathered.

Wired versus wireless systems: When deciding to use a wireless system its best to review the pros and cons to ensure that a wireless system is the best application for the client. When comparing to standard wired systems, wireless brings flexibility, scalability, automatic commissioning and potential labor and material cost savings.

Flexibility: The fact that devices can be placed almost anywhere without wiring and after installation, gives wireless systems an immense amount of flexibility. As the space needs of the building change, the system can be modified with relative ease. This also allows for code required changes. As energy codes change, new devices can be added or existing devices can be upgraded to meet any new requirements with much less work than a wired system. The control of fixtures can be down to the individual level, thereby maximizing energy efficient control schemes.

Scalability: Scaling the system gives the end-user the ability to expand easily, integrate with other systems such as new third-party apps, upgrade to smarter sensors with more features and essentially create a system that is future-ready. No system is future-proof, but the goal is to make it as flexible and scalable as possible to meet the demands of the foreseeable future.

Figure 4: Shown is a general wireless system architecture. Courtesy: RTM Engineering Consultants

Figure 4: Shown is a general wireless system architecture. Courtesy: RTM Engineering Consultants

Current scaling options provide added value as they can provide space usage information from the system sensors. This gives the user the ability to see how building spaces are being used, such as underused areas, peak usage times, real-time room status and history logs. And in today’s COVID-19 environment, it gives users the ability to see if a space has been used and when it needs sanitizing.

Interfacing with other devices such as asset tags or employee badges via Bluetooth allows the use of systems like real-time locating system. RTLS would eliminate the need for a separate system to be installed. Third-party apps open the door to further connection for the end-user, giving them control of lighting from a phone. The system can enhance building security; with sensors in almost every light fixture, facility staff can detect intrusion after working hours by sending real-time data to the security system for review.

Automatic commissioning: Automatic commissioning can save time during startup. Many manufacturers now offer automated commissioning features that can be used to quickly get the system operational and to comply with the commissioning requirements of both International Energy Conservation Code and ASHRAE 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings.

The commissioning can be done live in each area via smartphone or tablet or from central location with a computer. During the programming process, various sequences of operation (such as daylighting zone dimming or time of day controls) may be automatically applied, thereby saving more time at the end of a project during commissioning.

Initial cost savings over a wired system can be realized when first installed, but will most certainly be realized if the building type is one that goes through many changes, modifications or additions. If the project is new construction for a building that has a layout that will remain mostly static over time, a hard-wired system might be the best option, pending pricing. If the project is new construction for a building that may goes through many modifications, or if it is for a renovation of an existing building, then wireless may be the more advantageous fit.

While the system should be less expensive to install because there are fewer wires, conduits, rough-ins or similar needs, keep in mind that most contractors are not familiar with these systems. Contractors might factor uncertainty into their cost. To head this off, it is important to get contractor buy-in early if possible.

The main cons of the systems are that they are relatively unproven outside the manufacturer’s lab, may come with proprietary software, may have a software as a service annual cost to use all features. Because the systems are relatively unproven, reliability is an issue. Reliability is a huge issue for any system in a building, but with lighting it can be a deal breaker due to the high level of building occupant interaction. Responsiveness or latency also can be an issue in wireless systems as they may not react as quickly to user inputs as hard-wired systems.

There are also challenges with open-source specifying or listing alternates for wireless systems. The requirements from one manufacturer to another can vary significantly (i.e., power connection locations, modules required, etc.) Equals and alternates can be confusing to show on floorplans and/or confusing for the contractor to accurately price.

User perception may be a hurdle to overcome. If fixtures are controlled individually to maximize energy efficiency, it could appear to untrained occupants that fixtures are broken or controls are malfunctioning.

Lastly, a wireless network needs to be established before the fixtures being able to be programmed. This could bump up the information technology installation timeline or require a temporary network to be installed for the sake of programming.

Figure 5: Typical network topologies can be categorized into linear and mesh. Courtesy: RTM Engineering Consultants

Figure 5: Typical network topologies can be categorized into linear and mesh. Courtesy: RTM Engineering Consultants

Best practices in wireless lighting design

Once the lighting designer has decided that a wireless system would be best for the client and project, it is time to carefully review options. Like with all new technologies, changes are happening rapidly.

It is important to understand the client and its ability to maintain and use the features specified. Once the building is open and operational, who will maintain it? Many times, systems are specified with such complex features or software systems that the client becomes frustrated with it over time and ends up never using it. Keep it as simple as possible to ensure the client will get the most out of the system.

On top of understanding the level of expertise of the operations and maintenance staff, designers must also consider and engage the IT staff. Both the wireless and wired systems come with networking needs and typically need virtual server space created. With that will come the cybersecurity aspect — are these systems secure enough to satisfy the IT team? Be sure to include and coordinate with the IT team responsible for the building.

Designers must consider open versus proprietary protocols for wireless lighting design. Open protocols allow for the use of different manufacturers and systems. A challenge is that there are many players involved, so there is a chance that if something goes wrong, there is no single party responsible. In these cases, it is important to discuss maintenance and issue protocol, so that system challenges result in resolutions in lieu of finger-pointing. Proprietary systems from a single manufacturer are typically made up of components tested to work with each other and have a single point of responsibility to make the system work. The downside to this is that in the long term, the lighting designer and building owner must use their products and potentially lose competitive pricing for both components and service.

Consider specifying systems that are using the emerging industry standards such as Zigbee, which uses the IEEE 802.15.4 standard operating frequencies and Bluetooth systems. Frequencies at the lower end of the standard will have a longer range, better obstruction penetration and less latency issues. Systems that use industry standards will also allow you to interface with other devices, third-party apps and use other building systems to control the lighting.

The BAS is commonly used as control for a building’s heating, ventilation and air conditioning system. BAS are capable of controlling lighting, security, fire alarm and RTLS as well. The benefits of this are that it simplifies things for staff building system maintenance. Most maintenance staff typically interface much more often with a building BAS and are therefore more comfortable and savvier when using it.

Keeping things simple is important. If another software package that the building maintenance team needs to know can be eliminated, that will make them happier and save on potential software costs. With wireless technology, lighting control systems can reside on a single pane of glass. And if the BAS is used, other systems can share that pane of glass, allowing the building team quick insights into the building status from anywhere.

Because options for programming become almost endless when every fixture has a sensor, providing a detailed sequence of operations is key to a successful installation. This includes carefully reviewing life safety codes to ensure the system specified meets the requirements for physical protection of wiring systems and failsafe operation.


Timothy Larson
Author Bio: Timothy Larson is a principal at RTM Engineering Consultants. He has more than 30 years of industry experience on electrical design projects.