Lighting control systems vary from individual light fixture controls to complex microprocessor-based dimming schemes that can be networked with building management system. As would be expected, more advanced the system, greater the potential for energy savings.
Lighting controls in most buildings generally use basic strategies like manual dimmers or automated controls that respond to programmed schedule, occupancy or available daylight. However, these systems restrict zoning to lighting circuiting and are not well integrated or share data with other building management systems (BMS) thereby, hampering deployment of advanced energy management solutions. This not only limits the flexibility and future configurability of lighting control system but also its latent energy-efficiency capabilities. But, with the advent of latest digital systems, the scenario has changed. The advanced lighting control options go beyond conventional automatic lighting control ability in terms of integration, flexibility and scalability. These networked systems offer a choice of control methods for different control tasks, ability to configure and reconfigure lighting control zones as per need and individual control of light fixtures (via unique IP address). The systems also provides central management capability with remote access and data sharing with building automation and energy reporting feature for benchmarking and measurement.
Furthermore, traditional lighting systems were designed to meet a single, consistent level of illumination regardless of occupant’s needs which resulted in over-lighting many a times. The task tuning of newer systems allow system administrators or individuals to instead tune down lighting levels in each area of a building via dimmable lights based on user requirements. Depending on the type of load and its ballast, different dimmers for dimming and relays for switching needs are used. Such as, for incandescent and halogen lamps, high power architectural universal dimmer or professional leading edge dimmer with necessary manual override switch and MCB protection can be used. CFL / Fluorescent load with DSI digital ballast can be controlled by C-Bus DSI gateway and load with 0-10 volt analogue ballast can be dimmed by DIN rail mounting 0-10 volt analogue output module. Also, DMX gateway and DALI Gateway can be used for suitable lamp/ballast technology.
Advance Lighting control approaches
Broadly, there are three technology platforms available for lighting controls. C-Bus on standard UTP Cat 5 cable, European BUS system KNX governed by IEC standards on KNX cables or DALI (digital addressable lighting interface) governed by DALI standards that works on DLAI cables. Sandeep Singh, Vice President, Lifespace BU, Schneider Electric India adds, “The biggest advantage of C-Bus lighting system is, that it has distributed intelligence. Each input modules has its in-built non volatile memory so, even if one of the modules fails the balance system continues to work. Whereas, in the case of systems which have centralized memory module or processor, whole system stops functioning if central processor fails. Moreover, C-Bus system works on standard UTP Cat 5 cables which are easily available and economical. C-bus system unlike others offers in-put modules with same aesthetic finishes as that of other wiring devices like Power and data sockets.”
The biggest advantages of DALI standard protocol on the other hand, are its inherent flexibility and simplified wiring scheme. DALI enables the construction of a lighting network using a low-voltage communications bus. Ballast control can occur locally via control devices and/or centrally from a PC with software. Zoning begins at individual ballast level as each ballast can be zoned separately or placed into controllable groups for larger zones.
Thus, lighting fixtures can be rezoned based on changing future space needs without rewiring, providing a high degree of flexibility. As an additional benefit, the communication path is bidirectional, enabling collection of data about light fixture energy and operating performance. Its potential disadvantages include a higher component cost, limited number of suppliers and the necessity of protocol such as BACnet, a gateway device to integrate a DALI-based control system into a building automation.
Although lighting control systems have proven to provide tremendous energy saving, but many building owners are hesitant to utilize these systems in existing infrastructure due to added cost of labor, wiring and the complexities of installation. Addressing these cost and complexity concerns, while increasing system capabilities is the new generation of wireless networking technology.
A wireless system uses a controller with an antenna that communicates wirelessly between a set of devices as against a controller of traditional lighting control system that is hard-wired to each device often with copper wiring. In wireless network technology, each endpoint (i.e. sensors, switches, and the ballasts or LED drivers connected to lights) is wirelessly enabled either directly by the device manufacturer or with an external wireless adapter. The system communicates commands between endpoints and a software system provides administrator or individual users with access to manage the system and change settings, routed through a controller to the individual endpoints.
Wireless network delivers system-wide control strategies without involving significant upgrades to existing lights or added costs. The technology offer full-featured control with added flexibility, reliability, scalability, ease of installation and use. The cost saving on wiring alone is incentive for many building owners to look at wireless systems – saving installation costs, reducing copper wire use, and improving payback time.
Better data often equals better savings. With advanced lighting control systems, real-time and previous information about the usage of energy by light, room, zone, building and more can be accessed. This enables building managers to verify results and make changes over time to get the most energy savings out of their system. Singh explains, “Energy efficient lighting strategy is a combination of time scheduling using latest technology platform like C-Bus, KNX or DALI to switch off lights during non usage hours, Argus Stand-alone or wired occupancy sensors based on PIR or Ultrasonic or dual technology for selectively occupied areas and a day light sensor which can measure the external light and adjust internal lights. The strategy also includes latest technology that offer various control possibilities like group control (address), individual lamp control or combination of both. In addition, for time scheduling of external lighting like street lights and facade lights, astronomical function is used where in once longitude and latitude of the location is fed in the device it automatically calculates sun rise and sun set times of all 365 days and does switching accordingly. A clear technological trend is the integration with BMS for which designers are asking of seamless integration of lighting controls with BMS system and preferably from the same manufacturer to have single point of responsibility.”
Moreover, lighting control systems can tie into utility demand management and peak-day pricing programs, allowing temporary reduction of building lighting during peak times to facilitate financial gains. Terry Mocherniak,CEO, Encelium Technologies, USA in his whitepaper “Using advanced lighting controls to drive down energy costs” says, “In advanced lighting control systems, the sensors are not assigned to lighting circuits via wiring, but instead assigned to individual fixtures and groups via software enabling overlapping, support zones and easy future reconfiguration. Thus, a building with sophisticated combination of scheduling, centralized control and individually addressable general lighting can actively engage its own load shedding strategies in a manner that is transparent to the occupants.”
However, as with many lighting technologies, particularly the sophisticated ones, adoption occurs over time and is a function of user’s growing comfort level with the system’s features and functions. According to Singh, “By day light harvesting only, every unit of electricity saved at end user point is equivalent to 4.2 unit of electricity at generation level. This can help reducing carbon foot print of India which is the fifth largest source of GHG (green house gas) in the world. Not surprisingly, with new national building codes including need for energy saving by lighting controls, government office buildings too are now adapting lighting control systems & solutions.”
Indeed, lighting control market is growing at the rate of 12-14% per annum and it has been observed that seven out ten buildings are integrating lighting controls with the same BMS screen, controlling building HVAC load. Bhavesh Mehta, Member, Indian Society of Lighting Engineers (ISLE) agrees when he states, “Most commercial building owners and corporate are including energy saving systems like IBMS for HVAC & lighting and advanced management solutions. The high cost of advanced systems though a deterrent, the awareness of short ROI & long term financial benefits is rising among end consumers.”