What is digital lighting, and how does it differ from analog? In this blog, we look at the differences between the two and explore why digital lighting is the better option.
DALI, EcoSystem, lighting addresses… these are all terms that many in the commercial building and facilities space have probably heard. But what do they mean, and why should anyone care?
What is Digital Lighting?
At its core, digital lighting refers to any lighting control system that achieves control through digital communication, as opposed to manipulating voltage, such as with a dimmer or switch. Digital controls have been around for decades… that keypad or button station on the wall, connected via a low-voltage cable back to a control processor? Yes, that device has been digital for years now. But what about the lights themselves? For most buildings, those lights have remained strictly analog components.
OK, But What is Analog Lighting?
Analog lighting is any form of lighting control that adjusts the power being sent to the light. Your traditional wall dimmer adjusts light levels by increasing or decreasing the voltage running to a fixture. This increased or decreased voltage has a direct effect on the output, more voltage means more light!
Differences between low, medium, and high voltage.
For ages, the most common form of analog lighting was the two-wire dimmer (and this is still true for residential dimming). Simply run the hot wire between the dimmer and the light, connect the neutral wire, and voila! Dimming control!
In the commercial world, another analog technology is quickly becoming the standard… 0-10V control. Pronounced “Zero to Ten Volt,” this technology has become the go-to lighting control standard for most new buildings (You can learn more about why 0-10V dimming is so popular in an upcoming post). 0-10V installations feature not two, but FOUR wires to operate: the same two power wires referenced above, plus two low-voltage wires that carry direct current (DC) with some voltage between zero and ten.
0-10V dimming is more advanced than two wire, but 0-10V is still an analog technology. Why? Because we are still seeing the control system increase and decrease the lighting by raising and lowering a signal going to the lights. The only difference is that the 0-10V increase and decrease occurs on this new, low-voltage pair.
So, How is Digital Any Different?
This brings us to the point of this article… What is digital lighting? Well, let’s start by contrasting with our 0-10V setup. In both digital lighting and 0-10V dimming, each light fixture gets power, which is usually provided in the form of a hot wire and a neutral wire, carrying (in the U.S.) 120- or 277-volts AC. Next, in both digital and 0-10V lighting, the fixture gets a low-voltage pair of wires.
0-10V drivers and digital drivers.
So, what makes digital different than 0-10V? The difference can be found not in the number of wires, but in how we use this low-voltage pair. Instead of sending an analog voltage to these lights, we send digital data. We talk TO the lights, and in fact, the light fixtures can TALK BACK TO US! Rather than sending out a simple voltage to set a bunch of lights to a certain level, we can communicate with the fixtures themselves.
This two-way communication opens a world of benefits that digital lighting provides us. These benefits include:
- No bulky dimming equipment: Remember, with digital lighting, we are not “dimming” the lights, we are telling the lights to dim themselves. This means that instead of an electrical closet full of dimming equipment, every light fixture contains its own miniature dimmer (usually built into the driver). You only need a central node or processor to communicate with the lights.
- Individual addresses: This one is huge. In analog dimming, there is no way to differentiate between light fixtures, except through physical wiring. If two fixtures are wired together, they will both receive the same analog signal, and will both dim to the same level. With digital dimming, we can talk to every single light fixture independently! These individual addresses lead us to our next advantage…
- Simplified wiring: Addressable drivers mean that we don’t have to wire our fixtures together into zones, we just group them programmatically instead. During installation or commissioning, each fixture is assigned a unique identifier or “address.” The lighting software will typically group and combine these addresses into “zones” of light with easy-to-use names, like “Window Row 1” or “Conference Room 100 Screen Lights.” This ability to zone lighting programmatically can dramatically improve the efficiency and performance of a lighting system.
Take this simple floor plan as an example:
An example of a simple floor plan.
When using 0-10V controls, each dimmable group of lights requires its own switch leg for power and its own dimming pair for control. In this typical example, imagine a space near a window that would like three rows for daylight harvesting. That would require three separate 0-10V dimmers and switch legs. Add in that the emergency lights need their own emergency dimmers and switch legs, and we’ve added three more dimmers. Each accent zone needs its own dimmer, and in this example, Accent Front, Accent Rear, and Wall Wash are all added.
We also have four private offices in this example, with two zones each, which creates eight more zones of light and eight corresponding new dimmers, relays, and switch legs. That brings our grand total to 17 zones, each with its own 0-10V dimmer, relay, and associated zone-based power and signal wiring.
Now, let’s look at the same space using a digital lighting solution:
A normal circuit and an emergency circuit.
In this layout, we still need to power the emergency fixtures using an emergency power source, but that’s it! Each fixture is powered from the most convenient power source, irrespective of its lighting zone. The communication wires are looped along from fixture to fixture, following the most convenient path. During system startup, each fixture will be given a unique identifier, like so:
A power source with labeled fixtures.
Thanks to these addresses, the system can communicate to any fixture individually. The system can also group fixtures to create controllable zones. We know that fixtures 1, 2, 7, 8, 13, and 14 are all part of Daylight Row 1 and should be affected the most by daylight harvesting. We know that fixtures 33 through 38 are in Private Office 2 and should respond to that occupancy sensor. We know that fixtures 7 through 12 are emergency fixtures, and perhaps we would like them to operate as night lights as well and stay on with a low glow after hours for security purposes.
One of the best parts of digital lighting, however, is the ability to change this configuration on the fly. Maybe instead of three daylight rows, we would like four. In a 0-10V system, that change would require major electrical work to reroute the line and low-voltage wiring for the affected lights. In a digital system, it’s an hour’s worth of programming to re-group the zones with the new fixture address combinations.
Listening to Your Lights
When your light fixtures talk back, you should listen to them! Digital light fixtures can communicate back to the system, and in the age of information and the Internet of Things, we all know how beneficial this data can be. Smart drivers and ballasts can tell you whether they are operating normally or whether a ballast, driver or lamp has failed. Digital lighting systems can track operating hours on lamps for preventative maintenance purposes and typically have even more detailed reports available, including energy data, occupancy information, space utilization reports, and more!
What Are Some Examples?
Most major lighting manufacturers feature some form of digital lighting, and each system type has its own idiosyncrasies. The best place to start is with DALI (‘DAH-lee’) or Digital Addressable Lighting Interface. DALI is an open standard, and as such, many manufacturers offer fixtures and controls that are compatible with the DALI standard. The standard is more prevalent in Europe than in the United States, but many manufacturers have DALI systems for sale here in the U.S., and several more have DALI add-ons and interfaces.
The most common digital lighting system in the U.S. is EcoSystem by Lutron Electronics. EcoSystem is built on top of the DALI standard, and so it follows all of the same rules and architecture described above. EcoSystem started as a holistic system type but has expanded into a technology that can be incorporated into almost every system type that Lutron Electronics offers, including some residential systems.
Lutron offers a whole line of EcoSystem components, including both the control components, LED drivers and fluorescent ballasts, and EcoSystem interfaces to make almost any light EcoSystem compatible. Many lighting manufacturers offer ecosystem compatibility for their fixtures as an OEM option, and some even offer EcoSystem as an integral component of their fixtures.
Does Digital Lighting Have Drawbacks?
There are certainly some downsides to digital lighting that need to be thoughtfully considered before choosing to go digital. First, digital lighting is not nearly as ubiquitous today as 0-10V and finding compatible parts and pieces can be more challenging than analog components. Also, the EcoSystem protocol requires Lutron-specific hardware to operate properly.
Another consideration is wiring. EcoSystem provides a huge benefit through its ease of installation, and the fact that your installers don’t need to pull all that extra wire to create dedicated switch legs and wired control zones is a huge plus. However, this means that once you go digital, you will likely have to stay digital unless you plan to totally renovate your space. A building with digital controls cannot just be converted to analog controls a few years later without electrical work being done.
Wrapping Up
Digital lighting provides some impressive benefits over its analog counterpart. As the lighting fixtures in your building get more powerful, the global shift towards LED is completed, and your fixtures begin to include things like controllable color and onboard sensor packages, analog controls are just not going to cut it.
Digital lighting opens up the ability really unlock the power of the most ubiquitous piece of technology in your building… the lighting. Whether it’s the two-way communication, reporting ability, ease of installation or flexibility of programming and zone configuration, there are a lot of really good reasons to consider digital lighting in your space.
Paratus Service Group provides lighting control solutions for commercial needs. As always, if you need any help with your current or planned lighting project, you can always contact us for support and expertise.
