KNX vs DALI

DALI is a well known Commercial Lighting control protocol that can be used with or independent to KNX. DALI allows the addressing of individual ballasts in lines of 64 luminaires (either individual or across 16 groups) for measures of light level control & reporting. For many years DALI has been a good solution for commercial projects but studies have questioned the cost benefit of using native DALI given it’s nature of being traditionally standalone.

Advantages of Native DALI

• Simple topology with no radial circuit requirements
• Requires less distribution board space
• Allows smooth dimming curves
• Ability to report on individual luminaire ballast (Dim Value, Condition, etc…)
• Quick solution to re-order/number luminaires for control groups

Disadvantages of Native DALI

• Estimates vary between 50-100% increase in cost of DALI over traditional phase dimming
• DALI is not as simple to commission, test and fault find
• DALI products are not tested for conformity (DALI2 was conceived to tackle this)
• DALI is ‘send and forgot’ meaning there is no fail safe for a lost ‘telegram’ (command)
• Often complex management systems with 2-3 intermediary systems for communication

Having discussed Native DALI, we can now take a look at what is often referred to as Hybrid DALI or KNX DALI. This system operates on the same principals as a traditional DALI system and so can deliver the same end result. In this system, all inputs (Sensors & Switches) sit on the KNX line whilst leaving the DALI line free to host it’s 64 ECG’s exclusively. The other core difference is that KNX is not a Lighting Control System but a Building Automation System (BAS). To elaborate further, KNX can offer:

• Lighting Control including constant light level control
• Auto-Testing of Emergency Lighting
• Temperature Setpoint & HVAC mode regulation
• Control of Motors including blinds, gates and doors
• Monitor Room condition (Co2, etc…) and Energy usage (Water, Gas & Electric)
• Interface with critical systems (Fire, SHEV, Intruder, etc…)
• Interface with all major protocols (MODBUS, BACNET, etc…)

Bringing this into a real world scenario, the same KNX Presence Detector that is controlling the light levels depending on motion and natural light, can also control the HVAC system in that zone, monitor the occupancy for intruder alarm functions, test and report the Co2, Pressure, Temperature and Humidity in the room and more.

KNX also offers further benefits for large commercial projects seeking to utilise a single lighting control system for both DALI and non-DALI luminaires, i.e.: Office Block in DALI whilst the Carpark would be simple on/off. Using KNX, it’s possible to snap on actuators to accomplish the on/off switching tasks without the expense of making the other luminaires DALI.

Collectively the solution offered by KNX DALI provides a remedy to the core disadvantages of what makes up native DALI, something that hasn’t gone unnoticed among commercial MEP specifiers.

For more info on KNX DALI get in touch or have a look at our product offering below: