14 Lighting, other control strategies save energy in plants, warehouses

Plant and warehouse managers looking for high-quality lighting levels with an eye on the bottom line can cost savings using today’s sophisticated controls.

There is no excuse for poor lighting in plants, warehouses, and distribution centers. These facilities support a variety of important tasks, from machine operation, assembly, and welding to picking, packaging, shipping, and receiving. Because multiple functions often are performed in the same area, different light levels are required.

Plant and warehouse managers are looking for high-quality lighting levels with an eye on the bottom line. Today’s lighting controls reach beyond occupancy sensors. Generally, lighting control can be divided by capability into room-based control; centralized wired control; and next-generation, open, wireless control.

Room-based controls tend to have limited capabilities with no central management. Wired controls are not very flexible in controlling various types of devices and so may not render a cost-effective solution.

While lighting control is critical, today’s open wireless control technology empowers manufacturers to also control thermostats, plug loads, fans, and CO₂ sensors (see Figure 1). Control technology advancements offer 14 control strategies to ensure the most effective lighting while also saving energy—up to 70 percent.

Figure 1: Today’s open wireless control technology controls more than lighting. It includes thermostats, plug loads, fans, and CO2 sensors. 

1. Occupancy Sensing
   Occupancy sensing is perhaps the most common of all lighting control strategies. A motion sensor, or occupancy sensor, detects movement within its field of coverage using passive infrared (PIR) or ultrasonic sensing technologies. Based on movement detection (or lack thereof) for a predefined period of time, lights turn on automatically or off when a space is not in use or dimmed, based on occupancy.

2. Dimming
   Although not always considered a true control strategy, dimming technology is used in several other strategies. Many lighting power supplies, such as ballasts and LED drivers, enable fixtures to be dimmed. Dimming the light to a fraction of its brightness uses a fraction of the energy.

3. Scheduling
   Most centralized lighting control systems provide some form of lighting schedule, the simplest example being a system that automatically turns off the lights after work hours. This is a “brute force” method of reducing energy usage, but it can be effective. Some systems allow local user override of the schedule via a wall switch, and the more sophisticated systems can create more complex schedules that alter other strategies based on time of day, day of week, and time of year.

4. Daylight Harvesting
   Also known as daylighting, daylight harvesting is the practice of reducing artificial light levels automatically when ambient daylight from windows, light pipes, and skylights is available. Daylighting systems typically use a photocell sensor (though alternate sensor technologies do exist), to measure ambient light. Based on the reading from the sensor, an algorithm determines the appropriate level of artificial light, if any, needed to supplement the natural lighting.
5. Task Tuning
   The core concept of task tuning is to reduce the maximum light output of each individual space to meet occupant needs precisely. Because light levels often are over-designed or made standard across a building despite the varying needs of occupants, many spaces are over-lit. Some control systems offer the capability to create lighting zones and determine a tuned maximum light level that is lower than 100 percent.

6. Demand Response
   The demand response (DR) strategy is less about saving money and more about earning money – by reducing energy demand at key, or peak times. Participants are reimbursed by utilities to do so. Many utility companies have set goals to distribute their loads better, reducing the demand for energy at the times of highest demand, such as hot summer days, in response to a signal from the utility. Lighting control systems can help by reducing lighting load during those times. Some control systems offer automatic demand response (Auto-DR) technology, which responds to a DR “event” and reduces light levels automatically.

7. Personal Control
   Various studies have proven the positive impact of a worker’s environment – and their control over that environment – on their productivity and workplace content. Often when occupants are given personal control over lighting, they actually use less energy. Advanced lighting control systems, from remote controls to desktop dimming switches, and virtual online switches can provide this control.

8. Energy Management
   The energy management strategy typically refers to a software system that enables a building or facilities manager to visualize, report on, and adjust energy usage. You cannot manage what you cannot measure, and centralized energy management software tools provide the capability to do both.

9. Automated Maintenance
   By monitoring and measuring energy usage at individual fixtures, some control systems can provide users the capability to know when a lamp is out or a sensor or ballast is malfunctioning. This information also can be used to estimate when maintenance will be required.
10. Building Management System Integration
    Some advanced lighting control systems enable integration with a facility’s building management system, typically via BACnet or another open protocol. Through this integration, the system’s user interface can provide integrated control and management functions. Although this strategy doesn’t save additional energy in itself, it does offer reduced management overhead (and the associated lower cost) for buildings that want to manage HVAC and lighting from a single console.
11. Plug Load Control
    Plug loads are rarely controlled but they represent a significant amount of energy waste. To eliminate that wasted energy, devices that are plugged into a standard plug strip or outlet (such as monitors or desktop lamps) can be plugged into a specialized plug load controller instead. The loads then can be managed according to a schedule or associated with an occupancy sensor.
12. Temperature, Humidity, CO₂ Environmental Monitoring
    Environmental monitoring sensors report on conditions in a facility and trigger alerts if those conditions exceed a threshold. For example, some data centers closely track temperature and humidity to prevent unplanned outages. In a lighting control system that supports this application, temperature and humidity sensors can be added to the network and report real-time data.

13. Wireless Thermostats
    A wireless lighting control network can be used to prevent the need to build a dedicated network just for thermostats. The network routes wireless control messages to and from the thermostats via the lights. A single building control network eliminates the cost of building separate parallel networks. Lighting serves as an especially robust base application for this network because of the large number of lighting nodes and their evenly distributed coverage throughout the building.

14. Other Independent Building Systems
    As with the environmental sensors, some standards-based control systems allow the addition of control over a variety of other devices. Some examples include automated window blinds, industrial fans, and security systems. By providing centralized control over these devices in addition to lighting, these advanced building networks can offer greater control from a single integrated solution and interface.

Simply having access to multiple control strategies does not necessarily make a system intelligent–sophisticated software is required in order to determine how those strategies should interact. It is important to look in-depth at a system’s capabilities and how it logically makes decisions to determine if it meets your needs.

Mandeep Khera is vice president, marketing and channels for Daintree Networks, Inc., 5150 El Camino Real, Suite E20, Los Altos, CA 94022, mkhera@daintree.net,  www.daintree.net.
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For more in-depth information about lighting controls, read Daintree’s white paper, “14 Strategies to Save up to 70% in Energy Costs Using the Latest in Warehouse Lighting…and More,” at http://sustainablemfr.com.

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