DALI is one of the latest buzz words in the lighting industry. Widely used in Europe, DALI is still in its infancy in the U.S., even though it was first introduced in the late ’90s. DALI stands for “digital addressable lighting interface”, a control protocol based on digital commands that are sent between ballasts and the control system. DALI has many benefits which make it a very attractive system for commercial lighting applications, however, there are a number of things to keep in mind when designing a DALI system.
How does DALI work? DALI is a standard digital communication protocol which allows DALI-compliant devices, regardless of manufacturer, to talk to one another. These devices include controllers, ballasts, switches and sensors. Since DALI is an open protocol rather than a proprietary system, there are a number of ballast manufacturers and control companies that offer DALI products.
A DALI system can include up to 64 individual DALI devices on a single loop, with each device having its own address. DALI ballasts can be individually configured, and that custom configuration resides in the electronics within the ballast itself. DALI ballasts are able to set light levels, fade time and fade rate, and individual address. These ballasts are able to be configured as part of multiple lighting scenes which can be selected by wallbox control devices or a central control system.
DALI ballasts feature two-way communication, which means that they receive digital signals from the control system telling them how to operate, while also allowing the ballast to provide feedback through the network, for instance, indicating if the ballast is on or off, how much energy it is using, and whether the lamp and ballast are functioning.
DALI systems have many attributes which make them worthy of consideration for commercial applications:
- With DALI, wiring is easier than in a traditional system and there is less of it. The electricians don’t have to care about how they circuit the fixtures. They just run power to fixtures the easiest way they can until they load up a circuit. Fixtures are controlled solely through the digital control wire, which can also be run arbitrarily to each device.
- The ballasts are individually addressable, allowing for control zones to be configured in the field – rather than on paper, prior to construction. Because control zones are not hard-wired, they can be easily reconfigured based on real usage. Programming zones and scenes is done through software, regardless of how the fixtures are circuited.
- DALI ballasts can be tied into Building Management Systems, which can monitor energy usage and identify lamp failures, making DALI an ideal system for clients interested in sustainability.
- DALI ballasts can dim to 1% for linear lamps and 3% for compact fluorescent lamps – this is of particular interest when considering daylight dimming along perimeter zones.
While there are quite a few positive features to a DALI system, there are a number of things to keep in mind when designing such a system:
- At the moment, there are a limited number of ballast types available. While the choices are vast in Europe, as of this writing, U.S. manufacturers only offer DALI ballasts for four-foot linear fluorescent lamps (T8, T5, and T5H0), two-foot T5 lamps, 18/26/32-watt quad- and triple-tube compact fluorescent lamps, and 40-watt biax lamps. There are no manufacturers in the U.S. currently offering a three-foot linear fluorescent DALI ballast. This proves problematic if designing continuous coves or slots, which can require three-foot units to make up a continuous lighted run.
- Something else to consider is the inability to locate a DALI-compliant ballast remotely. Lighting fixtures are becoming smaller and smaller due to the demands of both designers and architects, and in some cases the ballasts just don’t fit inside the fixture housings. For a DALI system, designers can select only fixtures with integral ballasts, because as of this writing, DALI ballasts cannot be located outside the fixture.
- Another factor is that many people are hesitant about implementing a DALI system because they just don’t know enough about how it works. There is the notion that a DALI system will cost more than a traditional system, however, one must consider the lower cost of installation and simplified wiring configurations.
While DALI might not be right for every application, and it does indeed have some drawbacks, the time might be right for more DALI installations in the U.S., and perhaps the U.S. ballast manufacturers will soon start developing and offering more options for DALI ballast/lamp combinations – especially when it comes to three-foot lamps!
Photo Credit: © Carlene Geraci/Lam Partners