It’s common knowledge that one of the easiest ways to save energy is to shut off lights when they are not in use. Even so, the lighting controls market accounts for a fraction of the overall lighting industry. The market is small, despite the benefits of control technology, because in the past energy consumption was not a high priority. In addition, frequently turning lights on and off reduces the lifetime of light bulbs by as much as three times. LED lighting eliminates traditional lifetime issues and is aligned to enable a rapid growth in the lighting controls market.
On its own, quality LED lighting can provide energy savings of 30% over fluorescent, and 65% over HID fixtures. When combined with controls and sensors, LED fixtures can further reduce energy consumption without compromising lifetime. As an example, the Dole Foods Atwater California sub-zero cold storage warehouse documented a 95% reduction in energy use with LED fixtures and smart controls.
Because, LED lighting is a solid-state technology with lowvoltage operation and instant turn-on, it is intimately compatible with digital control and sensor technologies. But navigating the process of controls selection and integration can be complex. Here are a few basics that everyone should understand.
Types of Sensors
Motion sensing is the most valuable way to maximize energy savings, by turning lights off as soon as people leave. There are multiple technologies available and cost depends largely on technology selection and how it is implemented. Some of the current technologies include:
- Passive infrared: senses body heat;
- Ultrasonic: senses objects;
- Sound: senses noise.
Systems that combine multiple technologies into a single system provide more robust solutions, but also increase system costs.
Daylight harvesting is growing in popularity and is very useful in applications that have significant window and/or skylight exposure. This approach senses when natural daylight is available and automatically reduces the use of artificial lighting. When combined with occupancy sensors, this strategy can provide a powerful solution for gaining additional energy savings from the lighting system.
The location of sensors can also have a big impact on performance for both occupancy and daylight harvesting strategies. Sensors can be mounted directly to the fixture or can be standalone. Standalone sensors can be placed in an optimum position for controlling fixtures, including locations where there may be no fixture. The drawback is that these standalone sensor installations require additional wiring and power. Better performance is usually associated with a higher density of sensors and carefully placed sensors, while costs favor a more dispersed solution. This density/cost dynamic can lead to a wide range of performance levels depending on whether density or cost takes precedence. Care must be taken in the design phase to ensure the correct value is delivered to the end customer.
Wired vs Wireless
Once the sensor types and locations have been determined there are several interconnectivity considerations. One is the link between the sensor and the fixture, and the other is the link between the sensor/control system and an energy management system.
Sensor to Fixture
Since dimming or turning the light on and off requires interaction with high voltage, the link between sensor and the fixture often requires at least two parts: the low-voltage sensor signal and the power regulation. On wired systems both of these functions are often contained in a single module, while wireless systems require a receiver module in the fixture that links to the remote sensor. The remote sensor will need power and that can be problematic if AC is not available. Manufacturers are using batteries, or other novel technologies, to provide the remote unit with power. However, this can limit the value of the system for some users.
Sensor to Energy Management System
A growing trend is to interface the lighting control system to an energy management system that provides a wide range of interactive capabilities to set-up, control, change, and monitor. A wireless interface to this system greatly simplifies installation, although in some facilities hardwired options can be preferred. Although a large number of these systems use proprietary protocols, a number of companies are developing systems based on new open source specifications that future-proof expansion and upgrade capabilities.
In contrast to external sensors and controls, a growing number of LED lighting fixtures are featuring embedded controls. This saves on the costs of external wiring of the additional sensors, and can be very useful in areas that are physically constrained and cannot accommodate a bolt-on control product, such as under-cabinet lighting.
Embedded controls can also add high-value features including thermal management of temperature. LEDs operate at their highest efficiency when they are cool, and extended exposure to heat above 50°C can shorten their lifetime. Thermal management sensors and controls embedded within fixtures can decrease light output at certain temperatures to protect the lifetime of the fixtures.
Albeo manufactures an industrial high bay fixture called the H-Series that has demonstrated superior thermal management. When the H-Series internal sensors detect the temperature of the unit rising above 50°C, it will reduce its light output by a small fraction. This reduction in light is minimal and significantly protects the light fixture. If the unit reaches 60°C, light output will ramp down even further, and turn itself off after reaching 65°C (or 149°F).
Since there are no established standards on embedded thermal management, several LED manufacturers have introduced embedded thermal management controls with varied success. Some fixtures have such poor thermal qualities that even at ambient temperatures, the fixtures become so hot that they ramp down light levels to protect the fixture. So when evaluating light fixtures and thermal management controls, be sure to request granular ramp down data and check to see if the fixture’s output is guaranteed up to a specific temperature. Companies selling quality products will provide this type of information.
LED’s are the unique enabler to change what were once plain light fixtures into intelligent platforms. This change will go beyond turning lights on and off to add new functions and benefits that create new value points and market opportunities. We are at the very beginning of this change, and exciting times lie ahead as we start to explore this new space and its possibilities.
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