Lighting

How to switch to wireless lighting controls

Wireless lighting controls are making installations and code compliance easier on retrofit and new construction projects

By Michael McTavish April 30, 2021
Courtesy: Dewberry

 

Learning Objectives

  • Understand how wireless lighting systems simplify compliance with energy codes.
  • Know how best to specify a wireless lighting control system.
  • Learn additional installation variables to consider during the design.

With each release, energy efficiency codes have required more automated lighting control for increased energy savings. Regardless of whether the local municipality follows ASHRAE 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, the International Energy Conservation Code, California Title 24 or some other code, simple lighting controls don’t comply. Modern codes require the following control methods:

Courtesy: Dewberry

Courtesy: Dewberry

Controlling lighting has become much more complex and will become even more complex with each code release. Each project, space type and code have different requirements, allowances and exceptions. The lighting designer must evaluate the best code-compliant system on a project-by-project basis.

To comply with the applicable sensors, wall stations, load controllers and other accessories must be provided along with the appropriate control wiring for the system to function correctly. In new construction, this is easy to plan for and coordinate into the design. However, existing conditions often make code compliance difficult. Hard ceilings, block walls, high ceilings, glass storefronts and historic architecture all pose challenges to implementing energy-saving lighting controls using wired systems. Additionally, certain sensors are programmed with dip-switches or by some other on-device means. This makes adjusting the devices after installation a cumbersome task. These are the instances where wireless controls are the superior solution.

Many manufacturers have devices that are self-powered and communicate wirelessly; although there are slight differences in how this is accomplished. They may be stand-alone systems or networked into a larger building or campuswide system. Some lighting control systems interface with the heating, ventilation and air conditioning control systems via the BACnet protocol or other building management system protocols. They essentially can do what wired systems do, without the wiring. This reduces installation time and effort.

Consider space in an existing building. If this space were a classroom with more than 24 square feet of exterior glazing and more than 120 watts of lighting load in California, Title 24 would require:

  • Light fixtures with dimming capability.
  • Occupancy-sensing controls for automatic on to 50% output or on by manual control only.
  • Automatic shut-off when room becomes vacant.
  • Manual wall controls with on/off and raise/lower light level control.
  • Daylight control to dim fixtures in response to available daylight for each daylight zone.

This is a significant amount of additional control equipment that needs to be installed in just one space. Wireless controls simplify the installation by eliminating components.

With traditional, wired control systems, the installer would need to provide access panels in the gypsum ceiling to install the power pack that provided on/off control of the line voltage source. It would also provide the dimming output, usually 0 to 10 volts, which would necessitate low-voltage control wires to each fixture. Low-voltage wall stations and occupancy sensors would be required for the manual and automatic controls. This wiring would need to be fished into walls and ceilings or run through surface raceway to each new device.

With wireless controls, each fixture has its own sensor and wireless transmitter. It talks directly to a wall switch that provides the on/off and raise/lower controls. The receptacle itself may be wireless and get signals directly from the sensor to turn the plug load on or off based on space occupancy. The bill of materials is significantly reduced and the amount of disruption to the existing architecture is minimized.

Control of exterior lighting also has become much more complex. In addition to on/off controls for the fixtures, light fixtures are required to dim to partial output and respond to movement after building closed hours. When upgrading pole mounted fixtures, accomplishing this level of control often requires upgrades of the system circuitry.

Consider the following scenario: existing parking lot pole-mounted light fixtures are being upgraded to LED. The current system has single-controlled circuits to each pole. The IECC, ASHRAE 90.1 and Title 24 all require that the fixtures be equipped with a lighting setback. Depending on the code, the light fixtures all need to have a reduction in wattage of at least 30% based on time of day or occupancy. An easy solution is to provide independently wired drivers that are switched separately providing 50% output.

However, if there is only one controlled circuit installed, the dual switching is not possible without adding a second controlled circuit. An alternate solution would be to provide a wireless control system to dim fixtures to 50% via wireless signal that is networked to a BMS. The BMS would provide astronomical time schedules as well as automated demand response control.

Figure 1: This shows the contrast in equipment required for a wired and wireless control scheme for a typical classroom. Note the elimination of stand-alone sensors and control cable with wireless system. Courtesy: Dewberry

Figure 1: This shows the contrast in equipment required for a wired and wireless control scheme for a typical classroom. Note the elimination of stand-alone sensors and control cable with wireless system. Courtesy: Dewberry

Specifying wireless systems

As the lighting control industry migrated away from centralized relay panels to room-based controls, the system architectures began to differ slightly from manufacturer to manufacturer. The same can be said for wireless lighting controls where every manufacturer seems to have a slightly different solution. Engineers want to get into the details of the system and understand how each piece part functions. There is comfort in doing a detailed design around a specific product, but often designers are not able to limit a specification to a single manufacturer.

Considering each system works slightly differently, it is beneficial to specify the system as a sequence of operations rather than showing every device and component. Going back to the example classroom, it may be worthwhile to show a sensor and switches on the floor plan to convey the location intent of the components that are architecturally visible.

A sequence of operations describing how the space is to function allows for each manufacturer to apply its system component as required. An example sequence of operations may be:

  • All light fixtures are dimmable and equipped with integral wireless control. Fixtures can be controlled together in identified zones or independently.
  • Lights come on only when manual wall switch is activated.
  • Wall switch located at entry has on/off and raise/lower control.
  • Six-button teacher station has on/off control and four preset scenes.
  • Daylight control for fixtures in identified daylight zones shall dim smoothly in response to available daylight to maintain a constant light level.
  • Fixtures shall automatically shut off when room becomes vacant (no occupancy sensed for 15 minutes).

This is beneficial when working on publicly funded projects where it is required to include multiple manufacturers in the specification. Showing every component may accidentally exclude a trusted manufacturer from the specification.

It is important to note that there are drawbacks with writing a sequence of operations. It is incumbent on the designer to make sure that essential information is included. If it is essential that each fixture is equipped with wireless control, this must be noted, otherwise, a solution may be provided with a wireless relay pack that controls multiple fixtures.

The relay pack may require an access panel, which was to be avoided for architectural reasons whereas the fixture-enabled controls would not. If the rationale for individual fixture control was to provide flexibility in the controls scheme, this would also be lost with a single relay pack. Therefore, it is important for the designer to find the right level of specificity.

Figure 2: In this lighting control scheme for a university classroom, the space was divided into four zones to accommodate daylight harvesting per the International Energy Conservation Code as well as the intended use of the space. An additional audio-visual interface was provided for integration with the AV system. Courtesy: Dewberry

Figure 2: In this lighting control scheme for a university classroom, the space was divided into four zones to accommodate daylight harvesting per the International Energy Conservation Code as well as the intended use of the space. An additional audio-visual interface was provided for integration with the AV system. Courtesy: Dewberry

Lighting system considerations

When specifying and designing the system, it is best to start with a broad view and then focus in on the control specifics. There are eight items to consider when developing the control scheme.

Does the system need to network multiple rooms together or can they be stand-alone?

If the code allows, the simple solution is to have each space function independently. The number of system components is reduced as well as the system complexity. If the facility is large or has multiple tenants or departments, centralized software control may be warranted. By not networking the system, the following functions are lost:

  • Centralized timeclock controls.
  • System monitoring and control from a central location.
  • Integration with the BMS.
  • Demand response control.
  • Fixture level information:
    • Power consumption.
    • Operating time.
    • Temperature profiles.

Does the owner want to integrate into the BMS?

Networked systems may function independent of the HVAC BMS. Often, the owner wants a single schedule to adjust, not multiple software programs to navigate. The system occupancy sensors also may also be used for HVAC system setbacks. By integrating the controls with the BMS, there is only one schedule to maintain.

How many zones of control does each space need to be broken into?

This is a consideration, regardless of whether it is a wired or wireless system. Often the number of controlled zones is obvious (primary daylight, secondary daylight, markerboard, wall wash, etc.), but some spaces, such as large conference rooms, lecture halls or open offices are not quite as obvious.

If there is any question about zoning, a wireless system should be considered. As the space is used, the owner may determine that additional zones are required for the space to function as needed. If the system were hard wired, the revisions to the system would be invasive. However, if each fixture were equipped with wireless control, rezoning the entire space could be accomplished without removing a single ceiling tile. All that may be required is a smartphone application.

How wireless does the system need to be? Are wireless sensors enough or does each individual light fixture need to be equipped with a wireless controller?

Wireless lighting control describes multiple types of systems. There are systems that communicate wirelessly to a dimming relay pack. From the relay pack, low-voltage control wiring is run to each controlled fixture. This allows the sensors and wall stations to communicate wirelessly, and each fixture still requires a low-voltage hard wired connection. Other systems place sensors in each fixture providing per-fixture control. This solution provides the greatest level of flexibility, but is more expensive for material. It also may limit fixture selection options as not all manufacturers will allow third-party sensors integrated into their fixtures.

If the space is relatively static, such as a private office, the dimming relay back would be the preferred solution. If the space were an open office with moveable partitions, individual control would be beneficial.

How important is network security to the owner and are they concerned with another system on their network?

If the lighting control system is stand-alone and does not connect to other facility control systems or the internet, there is little to no concern about network security. If the lighting control system is connected to the facility’s network or has an internet protocol address, attackers may use the lighting control network to attack other information technology systems. When specifying a system that networks with other facility systems, the facility IT department should be consulted. They can provide guidance on what is acceptable for connection as well as encryption and authentication requirements.

Does the system require an open protocol or can it be proprietary?

Most lighting designers do not want to get into this level of detail when it comes to specifying the controls system. However, it should be considered for future additions and adjustments that are made to the lighting control system. Wireless systems operate on short-wave radio frequency bands and the communication sent over these bands must be understood by each device in the system. The protocol is the common language that all system devices speak. Open protocols, such as ZigBee, allow for devices from multiple manufacturers to “talk” with each other if they are all speaking ZigBee.

For example, a fixture-mounted sensor from manufacturer A may communicate with a wall-switch controller from manufacturer B, as well as the thermostat from manufacturer Z. The obvious benefit is that interconnection between systems is easier and does not need any additional interface devices. Additionally, the owner is not locked into any single manufacturer when future projects require additions to the system.

A proprietary protocol that is manufacturer-specific is beneficial in that all devices are pretested to confirm that they work together. The benefit is that there is less programming of the system and if there is a problem with the system operation, there is no question as to who’s device is creating the problem. The drawback is that the lighting control system is locked in to one manufacturer and functionality between other systems requires interfaces to communicate. Any system additions will be locked into the original manufacturer.

Is there an emergency generator on-site and how to incorporate life safety egress lighting?

In the past, emergency lighting was just always on. “Night lights” always burned regardless of facility occupation. Part of the rationale was to safeguard so the emergency fixtures would not be switched off or dimmed. If normal power was lost, the fixtures needed to be at full output to meet the code-required emergency egress light level and uniformity.

Many wireless systems provide compliance with UL 924: Standard for Emergency Lighting and Power Equipment via switching devices that are either part of a switching/dimming wireless power pack or integral to the wireless-enabled fixture. The emergency fixtures can be dimmed and switched along with the rest of the fixtures. Unswitched normal power is monitored by the emergency transfer device. When the normal power is lost, the device forces the controlled fixtures to full output resulting in life safety code-compliance.

How is the programming of the system accomplished?

There’s an app for that. With most wireless systems, especially the proprietary ones, the programming is done in the controlled space via a smartphone or tablet. Bluetooth-enabled systems make programming simple without any additional wiring or proprietary control devices. Applications are often downloadable for free and make the system configuration and commissioning easier than previous control systems that required computers, cords and sometimes even walkie-talkies so that systems were operating as intended.

Additionally, adjusting system and device settings after installation is simplified as well. Sensor sensitivity, high-end trim-on fixtures, time-to-off delay and other settings can be adjusted without a ladder or removing ceiling tiles.

Many of the considerations above should be discussed with the owner, as they are the ones who will live with the system after the construction is completed. Often, the owner may not have an opinion other than how often they will have to change the batteries. They want a system that works, is easy to maintain and is cost-conscious. They are looking to the designer to figure out what is best and it is up to the designer as to how to best convey this information to the installer.


Michael McTavish
Author Bio: Michael McTavish is a senior associate and assistant department manager for Dewberry’s Midwest MEP group. He has more than 16 years of experience and has worked on projects for state/local, federal and commercial clients across the nation.