Introduction to Lighting Automation

By Craig DiLouie, Lighting Controls Association

Published April 2006

Lighting controls play a critical role in electric lighting systems, providing the function of:

• Turning the lights on and off using a switch; and/or
• Adjusting light output up and down using a dimmer

In recent decades, technological development has increasingly automated these functions and allowed integration of devices into larger, more flexible systems. The result is significantly expanding energy-saving opportunities, flexibility, reliability and interoperability between devices from different manufacturers.

One thing remains the same: A good lighting design includes a good controls design. The goal of an effective control system is to supporting the lighting application goals, which often translates to eliminating energy waste while providing a productive visual environment.

The Lighting Control System

Lighting control systems contain three components linked by communication wiring, which is used to transmit control signals, and power wiring, which supplies power.

We can therefore view a lighting control system or device as an apparatus that 1) receives information, 2) decides what to do with that information, and 3) changes the operation of the lighting system. In other words, we can look at lighting control devices based on inputs and outputs. Below are three examples.

Below is an example of a robust lighting control system with a control station, occupancy sensor, photosensor and time switch or centralized switching system providing a variety of inputs to the master lighting controller. The lighting controller can be a switching panel, dimming panel or both linked together. The controller in turn controls the lighting load with a variety of outputs based on decisions made by the logic circuits. Since different control strategies may have overlapping device requirements, control synergies can be gained by building a system of simple components.

Purpose of Lighting Controls

In many applications, the overall purpose of the lighting control system is to eliminate waste while providing a productive visual environment. This entails:

• Providing the right amount of light
• Providing that light where it’s needed
• Providing that light when it’s needed

The right amount of light ...

Control systems provide the right amount of light. This lighting decision is based on the type of tasks being performed in the space. Lighting controls support this goal in two ways.

Lighting controls provide flexibility in adapting the lighting system to different uses. For example, a school auditorium, which is home to a diverse range of activities, would need different light levels for these activities.

Lighting controls provide the ability for users to adjust light levels based on changing needs or individual preference, either through dimming or through bi- or multi-level switching. Dimming provides the greatest amount of flexibility in light level adjustment.

Photo courtesy of Lutron Electronics.

By enabling the lighting system to deliver the right amount of light to the task, the control system can eliminate energy waste while providing a productive visual environment.

... where it's needed ...

Lighting controls support the lighting system putting light where it’s needed. This entails establishing control zones, which is a light fixture or group of fixtures controlled simultaneously as a single entity by a single controller. Zones are typically established based on types of tasks to be lighted, lighting schedules, types of lighting systems, architectural finishes/furnishings, and daylight availability.

Photo courtesy of Lutron Electronics

The greater the resolution of the control zones—that is, the smaller they are—the greater the precision the control system can provide. For example, a control system can turn the lights on automatically when a person enters a building during non-operating hours. Only the areas to be used should be lighted, however, and not the entire floor. A zone can also be as small as single ballast or light fixture, which enables the greatest amount of control resolution. For example, each user in an open office can be given capability via PC or handheld remote to dim his or her own lighting to personal preference.

Generally, the smaller the control zone, the greater the control resolution and potential utility cost savings and the greater the opportunity to enable the lighting system to support visual needs.

... And when it's needed.

An effective control system ensures that the lighting system operates—and consumes energy which costs the owner money—only when it’s needed. Determining when the lighting system should be operating depends on how the space is occupied. This will entail whether a time-based or a threshold event should be the deciding factor in whether the lights should be turned on or shut off.

If occupancy is predictable, a time-based strategy can be considered. For example, a switching system can be scheduled to automatically shut off the lights by area, by floor or in an entire building if a building’s occupancy is predictable.

Photo courtesy of Leviton

If occupancy is not predictable, a threshold-event-based strategy can be considered. For example, occupancy sensors can be used to automatically turn on and shut off lights in areas depending on whether the sensor detects the presence or absence of people in the monitored area.

By ensuring the lighting system provides light only when it’s needed, the control system can significantly reduce wasted energy and generate utility cost savings for the owner.

Energy Management

Advanced lighting control devices and systems can be used to reduce ongoing costs for the owner and thereby increase profitability and competitiveness. According to the New Buildings Institute, lighting controls can reduce lighting energy consumption by 50% in existing buildings and by at least 35% in new construction.

• Lighting energy: Controls can reduce the amount of power drawn by the lighting system during operation and also the number of operating hours, thereby reducing utility energy charges.
• Lighting demand: Controls can reduce the amount of power drawn by the lighting system, reducing utility demand charges—particularly during peak demand periods, when demand charges are highest.

These cost savings can produce a short payback and a high rate of return for the investment in the new controls. In new construction, the rate of return is often higher because only the premium, not the total installed cost, will be recouped before positive cash flow is realized.

Visual Needs

The project may be driven by business benefits other than energy savings by providing increased performance and flexibility:

• Adapt the lighting for multiple uses of a space, such as a conference room or gymnasium.
• Adapt the lighting to evolving space needs resulting from employee churn and office strategies such as hoteling and hot-desking.
• Mood-setting for restaurants and similar applications.
• Increasing worker satisfaction by providing personal control of their lighting systems in office and other environments.
• Enhanced aesthetics and image, greater space marketability, and pollution prevention.

These business benefits are often more difficult to calculate than energy savings, but tangibly contribute to the bottom line.

Studies, for example, have shown that personal lighting control can increase worker satisfaction, a major contributor to productivity, while providing energy savings. According to the Building Owners and Managers Association (BOMA), energy costs run about $2/sq.ft. in a typical commercial building while worker salaries and benefits can run to $130/sq.ft. or more. While reducing energy costs by a large percentage can be profitable, increasing productivity by even a very small percentage can be much more profitable.

Energy Codes

Lighting automation is now mandated in most of the United States. With the adoption of the ASHRAE/IES 90.1-1999 model energy code by the U.S. Department of Energy as the minimum national standard, a majority of state energy codes require automatic shut-off of all lighting in commercial buildings greater than 5,000 sq.ft. in size, with few exceptions. Automatic shut-off can be provided by occupancy sensors and programmable time scheduling devices. Some codes, such as California’s Title 24, are even stricter. The 2005 Title 24 enacted in October 2005, for example, requires daylighting controls in some spaces as well as commissioning for control systems. Click here for a status of state energy codes according to the Building Codes Assistance Project.

Determining a Lighting Control Strategy

The below questions can help narrow down selection of an appropriate control strategy:

• What are the load and space characteristics?
• What are the project goals for the lighting system?
• What is required by energy, building and electrical codes?
• Should the load be switched or dimmed?
• What degree of automation is required?
• Should the lighting system be controlled locally, from a central location, or both?
• What degree of control accuracy is required?
• What is the target value level—the balance between performance and cost?

What are the application goals?

Click here for a list of common applications with typical application needs and control strategies.

Switching or dimming?

The first primary decision after defining the load and the application goals is whether to switch or dim the load. Switching and dimming are stand-alone strategies but are often used in the same facility, and may be integrated in the same control system.

When to switch

When to dim

Local or central control?

What degree of automation is required?

Manual lighting controls range from a single switch to a bank of switches and dimmers that are actuated by toggles, rotary knobs, push buttons, remote control, and other means. Manual controls can be cost-effective options for small-scale situations. However, as the size of the lighting system grows, manual controls lose their cost-effectiveness. In addition, manual controls often waste energy because the decision to shut off the lights when they are not needed is based entirely on human initiative.

Strategies

Above graphic courtesy of California Energy Commission.

What degree of control accuracy is required?

A key step in designing a lighting control system is to determine the degree of control over the lighting system, which means breaking the load up into zones. Establishing smaller zones increases control accuracy and flexibility but also increases cost.

Final Word

By determining the most appropriate control strategy for the application using these simple guidelines, one can specify control systems that provide the right amount of light where it's needed, and when it's needed—thereby optimizing operating costs and user satisfaction.

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