Control Devices vs Control Systems

By James R. Benya, PE, FIES, FIALD

What started as a dream in the 1970s – a computer-managed, building-wide lighting control system – has become a commodity of sorts. About a quarter of the product introduction and promotion emails I get daily are for some lighting control system, the majority using wireless networking methods of one technology or another. There are systems oriented towards office buildings, street lighting, high-end residences, smart homes, restaurants, hotels, retail, industrial buildings, and schools. Some are specialize for indoor lighting, others for outdoor lighting, and a few for lighting everywhere. One thing they all have in common – they are chosen to meet the control requirements in our energy codes, to meet the control requirements in voluntary standards like LEED or WELL, and/or to meet the control requirements of the building developer or a utility rebate program.

With all of the choices in the marketplace, how does a designer choose? After all, every basic LED lighting driver needs only two standard control inputs - switched incoming power of any normal voltage (120 to 277 volts in USA, 120 to 347 volts in Canada) and dimming with 0-10 volts (not including low voltage drivers used in PoE and some other systems). This leaves only one other standard method – switched phase-cut dimming – as being another significantly different type because of residential lighting and lighting retrofits into older dimming systems. This the first major consideration – what types of lighting loads are you using?

This alone is not as easy as it seems. For instance, there are both solid state drivers and transformer drivers for certain LED systems, like linear lighting. LED drivers for tape light, for example, might be transformer drivers for which phase-cut dimmers may be best. But solid-state drivers are most common for LED technology in general. It is best to get the recommended dimming information from the luminaire or system manufacturer. You may end up using some of each.

Next, are you using lighting control devices or systems? A device is assumed to be unitary, like a wall switch or dimmer. A system assumes the use of separate devices, like a low voltage or digital control device or station, and a driver that responds to specific commands from the device. A system might be one or more control stations controlling many lighting devices having different responses to the commands from the stations. In systems, you will likely have a mixture of driver types, especially in residential and hospitality projects.

The Dimensions ® D4206 Lighting Controller from Leviton.

Photo credit: Leviton

Third, primarily when using systems, you need to contemplate the complex of sensors and switches that will create inputs. Some functions, like dimming one channel up and one down, will be set according to a solar time (“astronomic”) schedule. Others might ensure that the lights will only operate with people present (“occupancy”), according to the settings of a manual control station, or a certain ambient light setting, or a combination of the three.

Finally, you will want to set the program that will include input triggers and control outputs like time or motion, scenes, scene rate of change, and settings at high and low for the scenes. This is the fun part, where you foresee the space relative to time, occupancy, or a photocell. If you don’t have a photocell, don’t worry. An astronomic time clock, which includes the solar time at the site according to date, latitude and longitude will take care of the outside world.

Now the most difficult part: how many and what control stations and sensors? For me, this is the most challenging. Do I give the client a lot of control, or do I maintain control based on inputs that I understand? A lesson hard learned among lighting designers is that clients may not agree with you. They may not want strict lighting controls or what they consider to be harsh transitions. Minimized will probably be best.

I think there are 4 major types of lighting designers:

1. They design high-end residential projects (quality, not total cost) and tend to prefer a specific brand or approach that favors personal choice.

2. They design corporate and business projects and tend to focus on energy conservation, daylighting integration and other considerations that favor the LEED and/or WELL points.

3. They design high-end retail projects where the shopping experience is tantamount and energy efficiency is secondary.

4. They design premium and high-end hospitality projects where the quality of the visual scene is primary, and users should not be able to screw it up.

Some of us wear several or all 4 hats, like me. From my experience, depending on the project, the best solution is to remain open to all players, and to narrow down your choice as the project progresses. In high-end residential projects, for example, I often find myself using a scene-based system in the common and “front of house” spaces and reverting to unitary dimmers and motion-controlled lighting in others. Very few residential clients don’t care about cost, and even fewer like overly designed lighting controls that deny them control over what happens. Hospitality projects should allow flexibility in function areas but still be easy to use. In my opinion, the hardest thing for a lighting designer to do is to simplify and dial back their expectations. We are all guilty of over-designing at first, because each of us in our own living room will spend an entire evening changing settings to perfect the ambience in real time.

Today, there is pressure to add two more types of lighting controls designers: those who design street lighting, and those who design industrial lighting. With the advent of wireless mesh networks, there is a lot of pressure to replace ordinary controls with dimmable systems for energy savings, motion controls and more sophisticated systemwide capabilities. On the surface, these systems are interesting to communities, but they are big investments.

Regardless of the application, above all, I heartily recommend working closely with the lighting sales agency that represents products you would like to use. Most agencies have a lighting controls specialist, an expert who is experienced in the product(s) they represent, and there are even some agents in major markets that specialize in controls. They have learned from prior projects what works and what doesn’t, what is not liked or does not work well, and what the customer usually prefers. Their ability to work with the factory to make it work right is one of the most important things that they do. That, and when the system is turned on, the best agencies have specialists that provide system start up, programming and tune up, services that are necessary and to-die-for important for complex and demanding projects. Another service that they perform is teaching the electrical contractor how to install and program the system. There is nothing quite like having the local expert for demanding projects and clients, especially when they want service immediately.

The Importance of Standards and Your Specifications

My design of a major university project employed a digitally networked lighting control system operating, among other loads, dimmable LED downlight and wallwash luminaires. Even though I specified a particular lighting control system and specific LED drivers, the owner (against my advice) accepted a “value engineering” proposal and directed me to write revised specifications to accommodate a different control system using 0–10-volt control and 0–10-volt drivers chosen by the luminaire manufacturers. I protested, but the owner’s project manager found the savings – over a quarter of a million dollars – too appealing to pass up. I wrote the revised specification section with, among other things, new language requiring the contractor to ensure the compatibility of the drivers and the system by testing.

A year later, an irate owner called me to inform me that the drivers were not working properly and created an unsafe electrical condition that was giving the electricians shocks at 277 volts. My research quickly determined that the drivers were not consistent with the approved shop drawings and were never tested for safety or performance with the lighting control system. I identified incompatible power supplies for the control system and for the drivers, causing dangerous voltages on the neutral conductor. Despite the fury of the owner over the cost to replace the drivers in all 450 of the luminaires (mostly in drywall ceilings), my well-written specification kept me out of the legal morass as all the other parties had to sort out the $500,000 tab.

The Life Cycle of Controls

A client called recently regarding a 2007-era modest-sized office project. It was a pushing-the-state-of-the-art facility with zero-net energy capabilities. I specified a network lighting control based on its performance capabilities and its ability to be reconfigured should the office be rearranged. I programmed the system and left it working very well, helping the project achieve net-zero in its first year.

Rearrangement time finally arrived in 2013, and I received a call. Their facilities manager wanted to know whether I had the Palm PDA with software so that they could re-configure it. As luck would have it, I never did use that Palm since the project was originally commissioned, and I sent it to them with a dead battery. I also called the manufacturer’s agent. I have made it a point to make the manufacturer’s agent a part of every design and the commissioning of the project, at least a little bit, and I expect them to keep a copy of the latest programming of the system. Between us, we were able to re-program the system as promised, and the agent then connected the system to the Internet in an acceptably secure manner so that future reprogramming could occur in a more normal way.

Buildings last decades, and owners expect the systems we specify to last, too, and to be serviceable throughout their life. I think it’s wise to consider whether the controls company being considered will be around to service and support their products in ten years or more. The lighting industry should follow the model of WiFi, with sufficient standards and backward compatibility, so that, even if a particular controls company fails, their products are sufficiently standardized that repairs and replacements can be obtained in the future. ■