Intelligent lighting control and energy performance
By designing intelligent lighting systems, lighting designers and engineers can achieve energy performance in a variety of building types.
- Understand the codes and standards that dictate lighting design.
- Learn the steps to design and implement a smart lighting system.
- Realize the importance of control system commissioning.
Lighting is typically one of the largest energy loads in any building, and historically it has been the hardest to control. People turn lights on and forget to turn them off. But technology has become more effective at combating this human weakness.
The first revision of the simple on-off switch on the wall was the replacement of the switch with a dial or slider incandescent dimming switch, which saved electricity by allowing the user to select intermediate levels of illumination. Then, in the thick of the energy crisis of the late 1970s, the first occupancy sensors hit the market. No longer were humans the sole determinant of whether the lights were on or off—now the machines also had a say. Stand-alone occupancy sensors and timer switches were connected to lighting fixtures, acting as a “big brother” and turning the lights off if no occupancy was sensed for a certain length of time, or when the time on the timer switch ran out. This innovation represented a tremendous improvement over the manual switch, bringing massive reductions in lighting loads.
Next came network-based lighting controls, which controlled lighting zones by layering a time schedule over stand-alone controls and manual switches, turning off all the lights in the building at a certain time, overriding the switches and the stand-alone controls.
The latest iteration, the advanced lighting control system, leverages the power of digitization and granularity. When properly implemented, these systems are user-friendly and easy to maintain, they provide the ability to effectively manage all of a building’s lighting from a single centralized location, and they streamline physical maintenance and operation. 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.
Despite the benefits, many engineers don’t really understand advanced lighting control systems. This may be because the comprehensive nature of the system can seem complex and overwhelming, and engineers often just haven’t taken the time to learn about it. The term “advanced lighting control system” may sound complicated, but what it really means is that you are merely layering communication interfaces over common hardware that engineers have traditionally used and are already quite familiar with—ballasts, lamps, occupancy sensors, and other control devices—or you are using a special type of this equipment. Often designers don’t realize that familiarizing themselves with advanced lighting control systems can save them time and energy in the long run. The hardware is pretty much the same as it has been; the real change and advancement is the software systems.
Updates to codes and standards
Energy codes such as ASHRAE Standard 90.1, International Energy Conservation Code (IECC), and California Title 24 are becoming more stringent, and advanced 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 the biggest changes are that the thresholds for triggering compliance are revised to encompass more projects.
As an example, let’s look at ASHRAE 90.1-2007 versus ASHRAE 90.1-2010 for some specific highlights:
- Threshold for compliance
- 2007: Any new or retrofit projects encompassing 50% or greater alteration of the connected lighting load
- 2010: Any new or retrofit projects encompassing 10% or greater alteration of the connected lighting load
- Automatic shutoff of lighting
- 2007: Required in buildings greater than 5,000 sq ft
- 2010: Required in all spaces
- Light level reduction
- 2007: Not a requirement
- 2010: Lighting must be wired to allow for a power reduction of 30% to 70%, in addition to turning off the lighting by either dimming or switching
- Daylight zones
- 2007: Not a requirement
- 2010: Daylighting control must be automatic based on natural light contribution, and must be installed in spaces with windows and skylights
- Exterior lighting
- 2007: Lighting must be off during the day
- 2010: Lighting must be off during the day, and lighting must be off or at a reduced level at night
- Plug load control
- 2007: Not a requirement
- 2010: 50% of receptacles in private offices, open offices, and computer classrooms must be automatically shut off.
Instead of looking at lighting control from a building level, many engineers still try to address each energy code requirement individually, 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, trying to fit a set of piecemeal systems together is really the harder way to go about things.
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 requirements. The thinking now is to make lighting controls as seamless as HVAC control—provide the user comfort, but only use 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.
There are essentially two types of advanced lighting control system implementation methods. The first is the use of digital addressable lighting interface (DALI) equipment. The address required for the system programming control is embedded in the ballast and control devices. The second is the use of addressable input/output modules that are “layered” over standard ballast and control devices. DALI-based systems seem to be proprietary in nature because you are restricted to specific equipment. Some DALI-based system manufacturers require their devices be implemented for proper operation. On the other hand, layered systems allow any device combination..
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. Software also provides unprecedented energy management power, by enabling centralized management (with remote access); easy 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 computing power, building operators are empowered as never before to optimize energy consumption in their facilities.