While the light-emitting diode (LED) has gotten a lot of attention in recent years, another revolution has quietly developed in the background: intelligent (digital) lighting control. The future of lighting is solid-state, and it will be highly controlled.
Fully realized, intelligent control allows zoning as granular as individual luminaires, detailed functional programming, zoning and rezoning independent of wiring, layering of control strategies, and two-way communication. This means highly flexible and responsive lighting can be controlled in layers of strategies that can be changed as needed, and the system provides energy and maintenance information.
An intelligent lighting control system comprises dimmable ballasts or drivers; accessory devices, such as switches and sensors; power controllers, which may be the ballast or driver; and supporting hardware used for communication and data storage.
The lighting controller—where the processor (or intelligence) resides—may be distributed (within the control devices) or centralized (within a central server). The power controllers are connected using dedicated control wiring or radio signals to build a network in which each controller has a unique identifier address. These controllers can be programmed and operated individually or in groups. Manufacturers use a variety of configurations, so it pays to get to know each system.
The solution may be luminaire-, room- or building-/campus-based. For years, standalone controls have been available as an onboard option. The latest generation of luminaire-based controls pairs onboard sensors and a controllable driver with LED luminaires that communicate with each other using low-voltage wiring or radio waves, and they can be preconfigured to simplify commissioning.
The majority of today’s intelligent lighting control systems are room-based. Each lighting control across the room or within each luminaire act as an independent control system. A typical solution includes plug-and-play sensors, switches and relay-based power controllers to switch and dim loads. Some systems are based on two-output controllers for two-zone control. Some feature wiring that allows rooms to be linked within a scalable building network. The systems typically offer preconfigured operation sequences that optimize energy savings and ensure energy code compliance. Simplicity is this type of system’s advantage.
The next step up is building-/campus-based solutions, which are typically centralized, meaning all devices communicate with a central server that authorized operators can access. This setup provides a single control point for a building or campus, facilitates ongoing lighting management, permits complex control-strategy programming, and can collect energy information and conduct monitoring for maintenance and recommissioning. Offering the best opportunity for energy savings and information, this option is the ultimate in lighting control, though it typically poses greater cost and complexity. For that reason, current commercial building penetration is estimated at 2 percent, though it is expected to grow.
Centralized intelligent systems represent the ultimate in lighting control, but they are sophisticated and require good design, installation and commissioning. Furthermore, manufacturers use distinct approaches to differentiate their systems. Designers and installers should familiarize themselves with the features and architecture of the various systems to ensure smooth projects.
Since centralized intelligent control systems are more challenging but have good growth potential, the remainder of this article focuses on them.
Centralized intelligent systems
Centralized intelligent lighting control systems must be connected within a topology. These systems may be wired, wired with wireless accessory devices (“hybrid”), or completely wireless.
Various wired topologies are available. The most common is a bus (basically a computer network). All control devices connect using one pair of low-voltage wires, Ethernet or proprietary cabling.
For greater flexibility, some wired systems incorporate wireless accessory devices (e.g., switches and sensors) that communicate with the system using one or more central gateways.
Alternatively, the system may be completely wireless with the majority using a self-healing mesh or star topology. In a self-healing mesh network, data flows through a network of devices along the most efficient path; if one device fails, the data routes through a different path (self-healing). In a star topology, signals from all wireless devices are transmitted within range directly to and from one or more gateways that form the network backbone.
The centralized intelligent lighting control system is designed in accordance with a common protocol. The protocol may be open (e.g., DALI and ZigBee), allowing products from different manufacturers to mix in the same network. On the other hand, it may be proprietary to a manufacturer. For the control system to integrate with a building automation system (BAS), the two systems must share the same native protocol (such as BACnet); alternatively, one can use a gateway and/or gateway-functional programming that can translate data crossing between the systems.
Centralized intelligent lighting control systems are set up and operated using server-based software that is accessible from a workstation. The programmer can create zones, discover devices, assign the devices to zones, set up schedules and control profiles, create users/access levels, and calibrate sensors. The operator can change any of this during the system’s life. Depending on the system, it can provide service alerts and alarms, and it can record energy use at designated intervals and display it for analysis. The system operator accesses the server using a webpage or program.
A control zone is where a lighting control governs one or more lamps or luminaires. Granularity refers to how detailed that zoning is; the smaller the zones, the more flexible the system is, which can translate to higher energy savings and user satisfaction. By making each luminaire addressable, intelligent systems facilitate granular zoning where useful. Because all controls are connected through a low-voltage wiring bus or wireless network, it is economical to layer control strategies on the same devices.
The ultimate in control responsiveness is for each luminaire to be addressable; to be installed with a dedicated occupancy and photosensor; and to be assigned to groups for scheduling, task tuning, demand response and basic manual control. However, this level of detail is not always needed. For example, in response to daylight, a photosensor could be used to dim luminaires to a certain level based on their proximity to a window. The luminaire layout, notably the density of luminaires used, can greatly affect control zoning with dedicated occupancy and photosensors.
After relating lighting and controls within control zones, we define the controls’ behavior, or sequence of operations. This requires a lighting control narrative that covers behavior under typical conditions, including all settings. In turn, this document provides a commissioning and system maintenance road map.
Once the desired operations sequence is defined, it is typically programmed into the control system using software. Time scheduling can be implemented using weekly calendars that also allow daily, monthly and yearly views. These time schedules also provide the framework for developing control profiles. The designer selects a block of time and assigns default or custom behaviors to the control system during those times using provided variables. These variables cover occupancy sensors (time delays, sensitivity, fade rates, etc.), daylight harvesting (dead-band zones, time delays, fade rates, etc.), manual override logic and so on. As systems vary in number of variables, the designer should choose one that allows satisfaction of all control narrative elements. Due to the sophisticated custom programs that may be produced, the system should provide a means of regularly backing up the program and all other data.
The software’s interface typically displays energy use in kilowatt-hours in various time increments (e.g., day), near real-time luminaire status (e.g., dimmed level), alarms and error messages, and demand response/demand reduction condition. Not all display instantaneous power (kW). Increasingly, software displays information about other operating parameters, such as temperature and occupancy. Most software can import floor plans and overlay them with luminaires and control devices; these floor plans are typically used to display information, though, in some cases, they can also be used to create control zones.
Some systems automatically send notifications about detected problems, which may include daily reports of equipment requiring service or replacement (e.g., failed lamps). These systems typically allow multiple recipients who can be assigned to receive different types of notifications. In addition, different users can be assigned different levels of access to control system functions. For example, the system administrator must have access to everything. Meanwhile, in a multitenant building, occupants may be given access to their lighting.
Documentation and commissioning
Construction documentation should include control schedules, indicating which lighting and control devices reside in each zone; a control narrative; and wiring diagrams. Because the topology and wiring methods for many new systems are different than the existing topology and wiring in many buildings, the installing contractor may wish to obtain samples of certain equipment to become familiar with it.
After installation, the system must be commissioned. The process typically includes the following steps. Energize the lighting system and verify that all wiring and system components are properly installed and powered, without any faults. Create zones using the software, discover all components in the system, assign lighting to the zones, and create control profiles and schedules for each zone. Calibrate the sensors. Identify and correct any faults in the system. Verify all software features are working.
The manufacturer should then provide training to the owner’s personnel. All documentation, such as operating and maintenance manuals, should be turned over to the owner.
Intelligent lighting control changes lighting as we know it from fixed, dumb systems into highly flexible, responsive and controllable systems. It will continue to gain in popularity as energy codes become increasingly complex and LED lighting becomes more common.