Networked lighting controls
With the advent of building technology comes the need for monitoring and intercommunication between heating, cooling, electrical, lighting, fire/life safety, and other systems for optimized efficiency and operation.
- Understand the basics of networked lighting controls in commercial buildings.
- Review codes and standards that address requirements of lighting controls.
- Discover how lighting controls can lead to better energy efficiency.
Lighting is typically one of the largest energy loads in any building, and historically, it has been the hardest to control. For example, have you ever wondered if people would really notice if you evenly reduced the output of light fixtures in a corridor or open space? Think of the energy savings. Thankfully, technological advancements have led to a solution that is extremely effective at combating these issues: networked lighting controls.
The networked lighting control system leverages the power of digitization and granularity to completely control a building’s lighting system from a centralized location. When properly implemented, these systems are user-friendly and easy to maintain—and they streamline physical operation and maintenance. Software-based lighting control also allows sharing of data not only between components of the lighting control system, but also with mechanical, fire safety, and security systems. This integration of smart systems enables effective management of all the building’s energy consumers to realize energy reduction and cost savings.
The term “networked lighting control system” may sound complicated, but what it really means is that you are layering communication interfaces over common hardware components that have been traditionally used—ballasts, lamps, occupancy sensors, and other control devices. The hardware is pretty much the same as it has always been; the real change and advancement is the software systems.
Updates to codes and standards
Energy codes, such as ASHRAE Standard 90.1: Energy Standard for Building Except Low-Rise Residential Buildings, International Energy Conservation Code (IECC), and California Title 24, are becoming more stringent, and networked lighting controls simply make it much easier to comply. With each new version, energy codes are trending toward the ultimate goal of net zero energy consumption. Each of the codes is updated every 3 years, and biggest changes are made to the thresholds for triggering compliance, which are revised in each edition to encompass more projects.
Instead of looking at lighting control from a building level, many engineers still try to address each energy code requirement on a space-by-space basis, installing multiple types of systems (e.g., relay control, architectural dimming systems, wall box dimming) in a single building without any central control. While this approach may satisfy the project’s basic functional and energy code requirements, it makes it difficult for building managers and facility operators to maintain. Having multiple systems to maintain is much more cumbersome than maintaining just one system.
Energy code requirements, rising energy costs, the importance of historical and up-to-the-minute building data-collection and analysis, research on the effectiveness of controls, emerging technologies like easy-to-control LEDs, and demand for green buildings have driven manufacturers to develop systems that engineers can implement to meet these changes. The thinking now is to achieve a seamless installation that provides user comfort, but only consumes what you absolutely need. With the addition of the plug-load control requirement, lighting control systems are quickly moving into the realm of energy management.
A review of networked control manufacturers will show that each manufacturer configures its hardware and software interface a little different. The major manufacturers fit into one of three categories:
- System type—all devices and components must be from the same manufacturer as the control system. The communication between hardware and software is embedded in the devices and components.
- Non-system type—devices and components can be from any manufacturer. The communication between hardware and software is layered over the top of the devices and components.
- Non-system type with digital addressable lighting interface (DALI)—devices and components can be from any manufacturer as long as they have the DALI protocol integrated. The communication between hardware and software uses the DALI protocol interface.
But what really sets these systems apart is the software interface. Several manufacturers now use a graphical user interface (GUI) that allows the user to point and click to make programming changes to the system. The allows the system to be easily adapted to changing building and workspace uses. Minor reconfiguration of spaces can be implemented through the control software without having to alter wiring or luminaires.
Software can provide unprecedented energy-management power by enabling centralized management (with remote access); integration and data sharing with other building systems, such as building automation systems (BAS), security systems, or fire alarm systems; and automatically generated maintenance alerts, device- and system-commissioning reports, and device-usage reports. Armed with all of this data and control, building operators are empowered to optimize energy consumption in their facilities.
Advantages of networked lighting control systems
Networked lighting control systems provide centralized control to ensure that all spaces can be optimized around energy savings and visual performance. The best combination of said energy savings and visual performance can be achieved by implementing six basic lighting control strategies:
- Time/astronomical scheduling: Lighting in a defined area turns on or off, or dims, based on a predetermined, customizable schedule.
- Occupancy/vacancy control: Lighting is turned on or off based on detected occupancy. With vacancy control, users must manually turn lights on, but lights are automatically turned off when a space is vacant.
- Daylight harvesting: Electric light levels are automatically adjusted to account for the amount of natural sunlight in a space. Appropriate light levels are maintained for functional purposes, and total illumination is evenly maintained throughout the space.
- Task tuning: Maximum light levels are set for a particular use or task in a specific room to prevent overlighting.
- Personal control: Individuals can tailor the lighting in their workspace to their personal preferences, via a GUI on their computer.
- Load shedding (or demand-response): Lighting control can contribute to a buildingwide effort to reduce demand. Lighting is turned off or dimmed in predetermined areas at times of peak demand.
In addition to maximizing lighting efficiency, these systems increase occupant satisfaction and possibly even productivity. When occupants have control over their space, they tend to be happier and more productive.
Best practices for design implementation
Energy codes (ASHRAE 90.1, IECC, Title 24) define functional requirements that must be met by lighting controls within the space. For example, for automatic daylighting control, ASHRAE 90.1 states that electric lighting shall be reduced with at least one control step that is between 50% and 70% of design lighting power and another control step that is no greater than 35% of power design.
The following examples spell out best practices for implementing current energy code requirements:
- Start with a simple user-triggered lighting strategy. In each area of the building, occupants turn lights on and off via a low-voltage switch. Electricity savings are maximized if users turn the lights on manually when they enter and remember to turn them off when they exit. If the user forgets to turn the lights off, automatic sensor coverage picks up the slack, signaling the central lighting control system to switch the lighting off in an area that is unoccupied or vacant, per energy code requirements. Vacancy sensors are generally considered more efficient than, therefore preferable to, occupancy sensors, because they only turn lighting off, not on—users have to turn lights on manually. In a private office with large windows letting in ample daylight, for example, the vacancy sensor ensures that the lights will only be turned on when occupants truly want or need them.
- In addition to the simple lighting switching strategy, the networked lighting control system automatically dims the lighting in areas that have adequate daylight penetration. As daylight levels change, the dimming levels of individual luminaires are adjusted so that the total illumination is evenly maintained throughout the space at the required level.
- The networked lighting control system controls emergency egress lighting. In the past, lighting on emergency circuits was often “on” 24/7 as a safety measure, burning through the night long after building occupants left. Advances in control devices now allow emergency lighting circuits to be controlled by time schedules or by automatic sensors. By equipping these devices with a UL 924 emergency transfer device that can override the digital lighting control system if normal power is lost, the system is able to turn on all lights connected to the emergency circuit and maintain egress levels for occupant safety without wasting energy when no one is around.
- The advanced lighting control system is digitally connected to the BAS to use the detection signal of occupancy sensors at all hours to adjust mechanical setpoints. If multiple lighting control zones are provided in a single mechanical system zone, the lighting control system can accumulate the occupancy zones within the mechanical zone to help refine the efficiency of the HVAC system.
One concern often voiced about networked lighting control systems is that they are expensive. To operate a networked lighting control system at the extreme of optimization, each light fixture would be individually controlled, therefore, equipped with a dimming ballast or driver. Such a system could be very expensive.
But a few things have helped make these systems become competitive. First, LED technology is increasingly affordable and is being used more frequently. One advantage of LED lighting is that it is inherently dimmable; if you pair the LED’s dimmable driver with a compatible control, additional components are not required to tune the light. The 20% to 30% adder for a dimmable fluorescent ballast over a standard fluorescent ballast has disappeared now that LED technology has become more mainstream and cost-effective, thus opening up the possibilities of light modularity as the norm instead of a novelty.
Second, as engineers have learned how to leverage networked lighting controls to manage energy usage, they have realized that significant savings in the system first cost could be achieved by thoughtfully grouping control of light fixtures into zoned areas and not relying on individual light fixture control, which is rarely necessary in typical building designs. Third, most networked control systems use distributed low-voltage components instead of more traditional “pipe and wire” control strategies, so costs associated with a less rigorous installation method can often be reduced if a savvy contractor is brought on to implement the design.
Another common concern is that networked lighting control systems are difficult to manage. But this is generally a matter of perception. When dealing with a building that has more than 1,000 light fixtures, the thought of individually controlling each of them can seem overwhelming. But, as noted earlier, individual control isn’t necessary, and careful planning can create a system that goes a long way to help facilities managers truly understand more about how their buildings really operate. Management of the entire building is done through web-based software. Anyone comfortable with using software on a PC will find this kind of system very straightforward to manage properly.
Rising energy costs and more regulation through energy codes are making energy management a top priority for building owners and facility managers. Networked lighting controls give designers additional tools to deliver solutions that both meet and exceed the expectations of current and future energy code regulations, while achieving client goals related to energy conservation, reduced operating costs, and improved lighting quality.
Robert J. Garra Jr. is vice president at CannonDesign. An engineering leader who understands clients and their goals, Garra applies his project leadership and industry knowledge across the firm’s market segments while providing strategic direction to the engineering group. He is a member of the Consulting-Specifying Engineer editorial advisory board.
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