Controls Archives - JDB Engineering, Inc.

By Craig G. Malesic, PE, LC, PMP

In our recent blog post about Lighting Trends, Thomas Schubert and I shared that lighting control systems are becoming very complex, the “why” is too often being ignored, end-users don’t understand the controls, and the lighting is often not properly commissioned. However, since ever-changing building and energy codes are driving the increased application of advanced lighting controls, I wanted to follow-up the trends blog with an overview of the various types of lighting controls.

Groups like the Illumination Engineering Society of North America (IESNA), the American Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE), and the International Code Council (ICC) create the various energy codes that have been driving adoption of advanced lighting controls. Specifically, the International Energy Conservation Code (IECC) and AHRAE/IESNA 90.1 are the enforced codes that determine the requirements for an energy-efficient design. These codes and guidelines dictate which types of controls must be used and how they must be configured. The primary purpose for the lighting design codes is to minimize energy used by selecting energy-efficient sources and to eliminate wasted energy by either turning off lights that have no reason to be on or dimming the lighting when appropriate. As the design and construction industry continues its march toward the goal of net-zero energy use in buildings, codes are doing their part by mandating increasingly stringent rules. With each subsequent code update, we see ever-decreasing allowed connected lighting wattage requirements. The good news is that sources such as LEDs use less total wattage per light output, existing design practices often result in over-lit spaces, and occupants easily adjust to lower levels of lighting.

Even with these increased requirements, not all spaces and applications are treated equal. Within codes there are exceptions included for specific cases. Because of safety concerns there are some applications where lighting controls could potentially lead to injury. The code is sensitive to this and provides a exception for potentially hazardous control schemes in these areas. For instance, a worker in a mechanical and electrical room doesn’t want the lights to automatically shut off while they are working on an energized electrical panel. A well-designed system does not provide this typical energy saving feature, but an inadvertent failure or poor design not taking these realities into account could be catastrophic. Another example would be a manufacturing or machining operation that has many moving parts, and therefore a risk associated with the space suddenly becoming dark. The code also allows exceptions for controls where security is an issue but is understandably vague. Because a reasonable argument can be made that application of a code in a particular area could pose a danger, it is generally accepted by code reviewers to forgo controls in these areas. In each of these situations, a designer needs to be careful where an exception is made and be prepared to present a reasonable case if questioned by the Authority Having Jurisdiction (AHJ).

Because of the many types of lighting controls available today, we’ll cover the options in a series of posts. This is not intended to be a design guide (that’s why you hire a professional lighting designer!), but rather an overview of the types of lighting controls, how they work, and basic applications. We will go beyond the often-used concept of “just” putting in an occupancy sensor. They certainly have a place, but I would like you to be able to navigate a well-thought-out lighting control scheme that may make more sense. To do this, you need to understand the options. I am a big believer that complex things can be simplified for all to understand and will attempt to remove the mysteries of the various ‘magical’ devices that we use every day. It may get slightly technical, but only at a general level. While you may never be called upon by a manufacturer to utilize the newest release of their lighting control product, it is still good to have a base understand of how it works.

The types of lighting controls that will be covered include:

Occupancy Sensors
Vacancy Sensors
Dimmers
Daylighting
Integrated Controls (within light fixtures)
Room Controllers
Scene Controllers
Whole Building Systems / Campus Wide Systems

There are codes related to each of these options, which we’ll cover as well.

Before we get started, your “homework” is to check out these other blogs, which will provide some foundational knowledge for our new series:

Lighting Trends: Everything is Changing, But Not Everyone is Keeping Up

Understanding Correlated Color Temperature

What is the Ideal Color Temperature for Your Lighting?

Illuminance and Perceived Brightness

Understanding Selectable Color Temperature

Ready to get started? In our next post, we’ll focus on the first three types of lighting controls:

Occupancy Sensors
Vacancy Sensors
Dimmers

Have questions about lighting? Looking for a professional lighting design team for your next project? Check out JDB Illumination and reach out to me at cmalesic@jdbe.com or 717-434-1559.

Connect with Craig

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Twitter: https://twitter.com/CMalesic

by Thomas Schubert, PE, Electrical Engineer

Most people would agree that saving energy is a good thing.

Unfortunately, a problem often occurs when we shift from principle into practice. Don’t get me wrong, there are certainly those individuals who turn off the lights when they leave a room, wear a sweater instead of turning up the thermostat, and prefer to drive the speed limit, knowing going any faster would waste fuel. But they are the minority. Most people aren’t motivated by the higher good but by simplicity. “Does saving energy take more effort? Not interested!”

This is why a shift in approach is necessary. Instead of trying to force building users to care enough to take the extra step to save energy, we should instead be making it easy for them to do so. Within the realm of lighting, this could be implementing lighting control systems that incorporate additional energy reduction, require no or minimal extra effort from users, yet doesn’t take away their ability to make lighting choices.

Occupancy vs. Vacancy Sensors

By this point everyone has experienced the occupancy-controlled room. When you enter, the lights turn on automatically. Upon departure, and after a set time, the lights turn off. While this scheme saves energy by eliminating the accidental illumination of an empty room for an evening or more, it also wastes energy when someone pops into the room for a moment or the sensor catches someone walking past it.

Most codes fix this problem with vacancy sensors. Instead of the lighting turning on automatically, with a vacancy sensor the user must press the light switch to turn on the lights. The sensor still works in the vacant case, turning off the lights after a set period of inactivity. This empowers the user to ask themselves if they need the lights on.

On to 50 Percent

Most of us are used to the traditional on-off switch. Flick a switch, and lights turn on to 100% full brightness; flick it the opposite direction, and the room becomes completely dark. Dimming is available, but has always come with an additional cost in any fluorescent fixture. Plus, people quickly learned that if they needed more light, they had to push the diming slider all the way to full lighting; they weren’t thinking about the quantity of light needed, only that they needed it.

A simple, yet powerful control strategy is to default all lights to turn on at 50% of their total output. The user then has the option to remain at the lighting switch, holding down the “on” button for a few seconds to increase the levels up to 100%. This allows for the user to have access to the lighting they need for the task, but also requires them to take a moment to request the extra lighting instead of giving it to them automatically.

Task Lighting

Most indoor spaces are over-lit. This stems from the need to light at a specific level for a specific space, a desk, or a work surface. However, instead of lighting that area, we typically fill the whole room with an equal amount of light. Every task requires a different amount of light, from working on a computer to writing a letter to building a circuit board. We don’t need the same lighting levels to walk to our desk as we do to work at our desk, so why do we provide it?

When designing lighting for a space, we first must understand the function of that space, and then layer lighting to each task. General lighting can be at a lower level, with specific lighting for the tasks being performed. The users should be able to decide when they need the additional lighting – and when it’s not required. Providing vacancy controls integral to the task lighting saves even more energy.

At the end of the day, as lighting design professionals, it is important that we create a new paradigm, and evolve beyond the unsuccessful model of solely relying upon users to make informed decisions to save energy, and instead provide the lighting systems and controls behind the scenes, simplifying the users’ decision-making process.

Thomas Schubert, PE is an electrical engineer with JDB Engineering, Inc. He holds a MS in Electrical Engineering from the Colorado School of Mines and has more than seven years of experience in the design of electrical systems.

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