by Craig DiLouie, LC, CLCP and C. Webster Marsh, CLCP
(This month’s special feature offers the complete text of the recent update to EE101: Introduction to Lighting Controls, originally written by Craig DiLouie and given a thorough update by C. Webster Marsh. It’s also available as a free video course here and as a written course in NEMA Academy, where you can take a quiz to earn education credit.)
A good lighting design is incomplete without a good controls design. Lighting controls determine when the lights turn On, when they turn Off, how bright they are, which luminaires respond, the response to daylight or occupancy, and how occupants interact with the lighting in the space. Controls may be simple or highly sophisticated, but every control system can be defined by the same fundamentals: inputs, outputs, programming, communication, and sequence of operation.
This content is written for those who already have a working knowledge of lighting and now need a foundation in lighting controls. Fundamental lighting controls concepts are introduced, such as inputs, outputs, and basic controls operations, followed by more sophisticated concepts such as. common control strategies, zoning, system architecture, communication methods, documentation, startup, and evaluation of manufacturer solutions.
Lighting controls may be as simple as a wall switch or as advanced as a networked system that supports scheduling, occupancy sensing, daylight response, color tuning, demand response, data generation, and integration with other building systems. In all cases, however, the system receives information, makes decisions, and adjusts lighting output accordingly.
WHY LIGHTING CONTROLS MATTER
Lighting professionals focus on providing good lighting design that supports visibility, comfort, safety, appearance, and energy performance. Lighting controls determine how the lighting behaves.
A lighting system without appropriate controls may provide the right amount of light, but not necessarily at the right time, for the right task, or in the way occupants prefer. Controls facilitate the lighting system response to people, schedules, daylight, energy goals, code requirements, and changes within the space.
At the simplest level, lighting controls provide a way for occupants or automatic devices to turn lights On, Off, and adjust light output. More advanced systems may also adjust the color of the light, collect operating data, support demand response, integrate with other building systems, and provide centralized management for the building’s lighting. To achieve the best results, controls should be understood as part of the lighting design itself and not just an add-on.
THE BASIC CONTROL MODEL: INPUTS, PROGRAMMING, AND OUTPUTS
Every lighting control system, from a simple wall switch to a building-wide networked system, can be defined by the same basic model: inputs, programming, and outputs. All devices in a lighting control system serve at least one of the functions identified in the model below.
An input is information entering the control system. It may come from a person pressing a switch, an occupancy sensor detecting motion, a photosensor measuring daylight, a scheduled event, or another building system sending a signal.
The programming is the logic that determines what should happen in response to an input. In a very simple system, the “decision” may be mechanical: flip the switch, and the circuit opens or closes (On/Off). In a more advanced system, the decision may be made by a controller, e.g., a microprocessor, a software platform, or distributed logic embedded in devices throughout the system.
An output is the command or commands the programming sends to the lighting based on those inputs. Commands may include turning lighting On or Off, dimming to a preset level, changing color temperature, or sending data to another building system (e.g., HVAC).
For example, in a private office, the input may come from a wall-mounted button pressed by the occupant. The programming may be a simple On/Off function or a preset scene. The output is the command or commands sent to the lighting to turn the lights On or Off or to implements the scene. In a daylit classroom, the input may come from a photosensor detecting available daylight; the programming may determine how much electric light is needed to adjust for the daylight level; and the output may be a dimming command to the luminaires in the daylight zone.
MANUAL VS. AUTOMATIC CONTROL
Lighting controls can be divided into two broad categories: manual and automatic. Most projects use both.
For manual control the input comes from a person interacting with a device. An occupant presses a switch, adjusts a dimmer, selects a scene, taps a touchscreen, or uses an app. Manual control is important because occupants often need the ability to adjust lighting for comfort, visual tasks, presentations, cleaning, maintenance, or preference. Even in highly automated systems, users should generally have some way to override or adjust the lighting.
For automatic control the input comes from the programming in a device or system. The lighting may respond to occupancy, vacancy, time of day, daylight level, building system command, or another programmed condition. Automatic control is especially useful for energy management because it can reduce or turn Off lighting when full output is not needed.
Manual control is often driven by visual needs: the user wants more light, less light, or a different scene. Automatic control is often driven by energy management or automation needs: the system reduces or eliminates unnecessary lighting based on vacancy, scheduling, daylight, or another building system command. Likewise, automated controls may turn lighting On based on facility operational hours or in conjunction with some other input signal such as detection of space or area occupancy.
Manual and automated controls often work together. For example, a classroom may use manual dimming for teaching needs, occupancy sensing for automatic shutoff, and automatic daylight response to reduce electric lighting near windows. Manual control gives occupants agency over the lighting in the space; automatic control provides a lighting system response behaves consistently whenever occupants leave, forget to turn lights Off or when daylight conditions change. Most successful lighting control designs combine both manual and automatic controls.
CONTROLS PROGRAMMING: WHERE DECISIONS ARE MADE
The control system programming, sometimes referred to as “intelligence”, determines the what lighting changes are needed based on system inputs. Controls programming may be simple or advanced, centralized or distributed, located in a single device or shared across many devices. Wherever it resides, its role is to evaluate inputs, apply logic and settings, and provide outputs for the required lighting response.
For a simple manual switch, programming is minimal. The user flips the switch which either removes power from the lighting or supplies power to it. In a more advanced system, the On or Off command may be issued by a controller, sensor, relay panel, luminaire-level device, or a combination of components.
Controls programming may be located in different devices within the system. In a centralized intelligence approach, decision-making programming resides in a central device, server, panel, or software platform that all input data is routed through. In a distributed intelligence approach, programming may reside in devices physically closer to the controlled lighting, such in room controllers, sensors, load controllers, or in the luminaires themselves. In a stand-alone device, programming resides in a single device that receives inputs and issues output commands, such as a wallbox sensor, dimmer switch, or time switch.
The location of system intelligence affects system flexibility, scalability, troubleshooting, resilience, and the ability to make future changes. A centralized system may make it easier to apply building-wide schedules or monitor operations from one location. A distributed system may allow rooms or luminaires to operate more independently and may improve responsiveness at the local level. A stand-alone device provides a simple, easy-to-install option for smaller spaces. Many systems use a hybrid approach, with some programming in local devices, other programming shared among a handful of devices, and other functions, such as schedules or global commands, managed centrally.
OUTPUTS: SWITCHING, DIMMING, AND COLOR CONTROL
The most common lighting control outputs are switching On/Off, dimming, and color or CCT control.
Switching is the simplest output. The control system turns a lighting load On or Off mechanically either by completing or interrupting the circuit or by sending an On or Off command. Switching is useful where the expected response is binary: lights are either needed or not needed. It is commonly used for automatic shutoff, plug load control, some exterior lighting, and basic manual control. Its limitation is that it provides only two states (or several if the luminaires are capable of multilevel switching), which can be disruptive in occupied spaces where a smoother or more flexible transition is preferred.
Dimming provides the ability to adjust light output above or below a given level instead of just turning the lighting On or Off. Dimming may be used for occupant preference, layering light, daylight response, or gradual transitions between operating modes. Changes in light intensity with stepped or smooth transitions between light levels make dimming well suited both for visual needs and energy management strategies such as daylight-responsive control and task tuning.
Color and CCT control are additional outputs made possible by LED technology. The control system may command a change in the CCT of white light (tunable white), imitate warm dimming (dim-to-warm), or saturate specific colors (independent LED array control).
Because control system outputs depend on compatibility among controls, load controllers, drivers, and luminaires, understanding the required outputs is essential before selecting devices or evaluating manufacturer solutions.
INPUTS: SWITCHES, DIMMERS, SENSORS, TIMECLOCKS, AND PHOTOSENSORS
Control system inputs may come from people, sensors, schedules, programming, or other building systems.
The most common lighting control inputs are manual devices, occupancy/vacancy sensors, time clocks, and photosensors. These devices are commonly required by energy codes and appear in many project sequences of operation.
Manual devices are user operated. These include switches, dimmers, keypads, scene controllers, touchscreens, and app-based controls. In older systems, a wall switch often controlled power to the lighting directly. In many modern systems, manual control is only an input-signaling device: the user presses a button or adjusts a slider, with power supplied to the lighting via separate wiring.
Occupancy and vacancy sensors detect whether a space is occupied and send that information as an input to the control system. The system programming may then issue commands to turn lights On, turn lights Off, dim them, or reduce them to a preset level.
An occupancy sensor may be used to turn lighting On automatically (i.e., automatic-On) when occupancy is detected and turn it Off after the space is vacant for a set time. A vacancy sensor provides automatic shutoff but requires the user to turn the lights On manually. This distinction is important because many energy codes limit automatic-On operation in certain spaces.
Image courtesy of Acuity Brands
A timeclock provides an input based on time of day. The system programming may command that lights turn On, turn Off, or reduce light levels based on preset schedule. Timeclock control is useful where space usage follows a predictable pattern, such as in corridors, manufacturing floors, school common areas, retail spaces, exterior lighting, or buildings with both normal and after-hours operation.
Image courtesy of Leviton
Photosensors, also called light sensors or daylight sensors, provide a measurement of the amount of light in a space. In daylight-responsive control, the system uses this input to reduce electric lighting when sufficient daylight is available to meet light level requirements and increase electric lighting when there is not enough daylight. Most energy codes require the use of automatic daylight-responsive control so that electric lighting is dimmed or turned Off when natural light sufficiently illuminates the space.
Images courtesy of PLC Multipoint
More advanced lighting control systems may also receive demand response, building automation systems, fire alarm systems, or other input signals. These inputs enable lighting controls to be integrated into a broader building operations strategy.
CONTROL STRATEGIES
A control strategy is the practical application of inputs, programming, and outputs to produce a desired lighting behavior. The table below provides common examples.
Manual control strategies, such as dimming or switching, allow occupants to turn lighting On or Off, adjust light levels, select scenes, or otherwise control the lighting. This strategy is important for energy code compliance in spaces where people perform varied tasks or need control over their visual environment.
Image (right) courtesy of Schneider Electric
Occupant-sensing strategies use detected presence to control lighting. The system may turn lights On automatically, reduce light levels when the space is vacant, or turn lights Off following a time delay.
Image courtesy of Acuity Brands
Vacancy sensing is a related strategy in the system turns lights Off automatically following a time delay. Lights must be turned On manually upon entering the space. This approach can save energy by allowing the occupant to determine if lighting is needed in the space.
Image courtesy of Leviton
Time-switch controls use a timer or preset schedule based on time of day, day of week, holidays, business hours, or after-hours conditions to turn lighting On, turn lighting Off, or reduce lighting to a lower level.
Automatic Daylight-responsive controls, sometimes called daylight harvesting, reduce electric lighting when daylight is available based on a photosensor input, maintain sufficient light in the space while avoiding unnecessary energy usage for electric lighting.
Image courtesy of IR-TEC
Task tuning strategies, also called institutional tuning or high-end trim, limit maximum light output to an appropriate level for the task or space, either because the installed system provides, at full output, more light than needed, or because the user prefers a lower light level, or to reduce energy usage while maintaining acceptable visual conditions.
Scene controls make use of preset lighting levels for the various luminaires or types of luminaires in a space to facilitate different activities that may take place in the space. For example, lighting controls for a classroom might include scenes for lectures, presentations, group work, cleaning, and after-hours use. Lighting controls for a conference room might include scenes for meetings, video calls, presentations, and maintenance.
Image courtesy of Port Lighting
Color tuning strategies may adjust either the CCT of white light or the color of the itself. Depending on programming or manual inputs, tunable-white systems may shift between warmer and cooler CCTs. Full color systems may produce saturated colors for entertainment, branding, display, or specialty applications.
Image courtesy of USAI Lighting.
More advanced lighting control systems may reduce lighting power in response to a demand-response signal or collect data on energy usage, occupancy, device status, or system operation. These strategies move lighting controls beyond local space control to encompass broader energy management, facility operations, and integration with other building systems.
CONTROL ZONING
Light sources that are all controlled by a single control output are referred to as a control zone. Lighting control strategies are, in part, determined by established control zones.
Control zoning is one of the most important parts of lighting control design because it directly affects flexibility, energy savings, user experience, and code compliance. Zoning that includes too many luminaires or is not consistent with how the space is used, may result in poor lighting system performance.
For example, an open office with windows should typically include at least two control zones. The luminaires near the windows may need to automatically dim in response to daylight while interior luminaires remain at a higher level. A classroom may need separate zones for general lighting, whiteboard lighting, and daylight areas. A conference room may need different zones so that scenes can support meetings, video calls, and presentations.
Larger zones are usually simpler and may cost less to design, install, and program, but they provide less flexibility. Smaller zones provide more granular control, which can improve responsiveness, occupant satisfaction, and energy savings, but they may increase system complexity. Depending on the control strategy, energy codes may impose limits on zone sizes.
Modern control systems have changed how zoning is achieved. Traditionally, zoning was often limited by the circuit wiring and switch legs. With networked, addressable systems, luminaires can often be grouped and regrouped via software rather than by rewiring. This allows more flexibility in making zoning changes, especially when spaces are renovated, reconfigured, or used in new ways.
SYSTEM ARCHITECTURE
Based on an understanding of the purpose and application of lighting controls, an appropriate control system for a given space can be identified, starting with system architecture. The system architecture describes how the lighting control system is organized: where the control programming resides, how devices communicate, and at what scale the system operates. Architecture matters because it affects cost, flexibility, start-up, commissioning, maintenance, troubleshooting, integration, and future expansion.
Architecture should be selected based on project needs. A small storage room may only require a standalone sensor. A classroom may require a room-based control with manual override, occupancy sensing, daylight response, and scenes. A large office building may benefit from networked controls for scheduling, reconfiguration, energy reporting, and facility management. A campus may require a network enabling control communication between multiple buildings.
COMMUNICATION METHODS AND INTEROPERABILITY
Devices in a lighting control system need some way to communicate for the exchange of information.
Lighting control communication may be wired or wireless. In a wired system, devices communicate through conductors such as low-voltage control wiring, digital communication buses or Ethernet cabling. In a wireless system, devices communicate using radio-frequency signals. Both approaches can be effective; the right choice depends on project conditions, system requirements, installation constraints, building construction, owner preferences, and manufacturer limitations.
Communication may either be analog or digital. Analog methods, such as 0-10V dimming, use an electrical signal to communicate a control level. Digital methods send information using either standard or proprietary digital protocols. Digital communication provides for more addressability, feedback, programming flexibility, diagnostics, and integration than simple analog control, but it also requires attention to protocols, configuration, and compatibility.
A protocol is the set of rules that allows devices to communicate. A protocol may be either analog or digital. It defines the behavior of components in a system and ensures compatibility between devices for exchanging information. Examples of protocols are 0-10V (analog), DMX512, DALI, and Bluetooth (digital).
Interoperability indicates that devices or systems with differing protocols can not only exchange information but also use it properly to perform their intended functions. Simply using the same broad communication method does not always guarantee that products will work together as expected. Two devices are not necessarily interoperable even if they use the same communication protocol.
Communication methods have design consequences. Wired systems may require specific cable types, wiring topologies, maximum distances, device limits, termination requirements, or installation rules. Wireless systems may require attention to range, obstructions, network topology, battery life, signal reliability, cybersecurity, and interoperability with other wireless systems.
Communication also matters when lighting controls integrate with other systems, such as HVAC, building automation, shading, fire alarm, or demand-response platforms. In many cases, different building systems may use different protocols and require a gateway or software interface to exchange information. The key is to define what information needs to be exchanged, which system is responsible for each action, and how the interaction will be tested.
Image courtesy of Daintree
DOCUMENTATION: CONTROL INTENT AND SEQUENCE OF OPERATIONS
A lighting control system cannot be successful if the project team does not clearly define what the system is supposed to do. As controls become more capable, the need for clear documentation becomes more important. Devices alone do not describe the design intent; the project must also explain how those devices are expected to behave.
A Control Intent Narrative (CIN) describes the intended operation of the lighting control system for a specific space type in general terms. It explains the concept of how the system should support the owner’s goals, user needs, code requirements, energy performance, and space functions. It is often developed early in the project’s design and helps align the owner, designer, engineer, contractor, manufacturer, and commissioning provider around the intended control approach.
A simple example of a CIN for a private office:
In a private office, the lights are manually turned On by the wall control. When the space is vacant for 20 minutes, the occupancy sensor turns the lights Off. The user may dim the lighting manually at any time. If the space is in a daylight zone, the lighting dims automatically in response to available daylight.
A Sequence Of Operations (SOO) is more detailed. It describes what each control point or zone should do in response to specific inputs. For example, it may define what should happen when a space becomes occupied, when it becomes vacant, when daylight is available, at when a user presses an override button, at a scheduled time, or when a demand response signal is received.
A simple example of an SOO:
Other documentation may also be needed depending on project complexity. These can include:
• Control zone plans
• Wiring diagrams
• Single-line diagrams
• Functional test forms
• Owner’s operations and maintenance manual
Documentation is also important after construction is completed. Owners and facility staff need to know how the system is intended to operate, how it is programmed, how to make adjustments, and how to maintain performance over time. Without clear documentation, even a well-designed control system can become difficult to operate, troubleshoot, or modify.
Control intent, sequences of operation, and supporting documentation translate the desired lighting behavior into instructions for the project team to use to design, install, program, test, and maintain the control system. Good documentation reduces confusion, supports bidding and installation, guides commissioning, and gives the owner a usable record of how the system is designed to work. Course EE105: Lighting Control System Design provides more information about how to design and document lighting control systems. The Lighting Controls Academy also offers a free Sequence of Operations template available at: https://lightingcontrolsacademy.org/design-express/. STARTUP, PROGRAMMING, FUNCTIONAL TESTING, AND COMMISSIONING
Once a lighting control system is installed, it still must be made operational, programmed, tested, and turned over to the owner. This is the point at which many control systems either succeed or fail in fulfilling project requirements. A system may be correctly selected and properly installed, but if it is not programmed, tested, documented, and explained to the owner, it may not perform as intended.
Image courtesy of Schneider Electric
Programming is the process of entering the intended control strategies into the system. This may include assigning devices to control zones, setting occupancy time delays, establishing daylight setpoints, creating schedules, setting high-end trim levels, defining scenes, configuring user interfaces, and setting up integration points. The programming should follow the sequence of operations and other project documentation
Image courtesy of Leviton
Commissioning is broader than startup or functional testing. It is a quality assurance process intended to confirm that the owner’s project requirements are reflected in the design, construction documents, installation, programming, testing, turnover, and operation. It is common to misuse the word “commissioning” when referring to startup or programming alone.
Image courtesy of Cooper Lighting Solutions
Startup, programming, functional testing, and commissioning turn a lighting control design into a working system. These steps are essential because a lighting controls system is not complete until the system operates as intended, and the owner knows how to maintain that performance over time. STARTING PROJECTS
Rather than beginning with a product or device, a lighting controls professional begins by asking what the space needs the lighting to do, how users will interact with the system, what inputs the system needs, what response is required, and how that behavior will be documented, tested, and maintained.
Here is a typical list of questions to ask at the outset of a project:
1. What does the lighting need to do in the space?
2. What is proper lighting for various tasks at various times?
3. What system architecture fits the project?
4. What control strategies are being applied?
5. Are the control intent narrative and sequence of operations clearly documented?
6. What inputs does the system need to accomplish the design requirements?
7. How will users interact with the lighting controls?
8. What outputs must the system produce?
9. Where will the controls programming be located?
10. Which luminaires should respond as a group?
11. How do devices communicate?
12. Is device interoperability confirmed?
13. How will the system be programmed and tested?
14. Can the owner operate and maintain the lighting controls after turnover?
A strong understanding of lighting controls includes knowing how to connect occupant and space needs to control behaviors, identifying appropriate inputs and outputs, identifying where controls programming should reside, recognizing the importance of zoning and communication, and determining if the intended operation has been clearly documented and tested. With this information, it becomes easier to evaluate solutions, ask informed questions, and participate more effectively in lighting control design, installation, and operation.
