KNX Group Addressing Overview & Tips

In KNX building automation, group addressing is a foundational concept that determines how devices communicate and interact. Despite its importance, many integrators default to the structure they were initially taught, often overlooking the advantages of a more strategic approach. A thoughtfully designed group address structure not only simplifies programming but also enhances clarity, scalability, and troubleshooting efficiency.  

This article explores the key methods of structuring KNX group addresses—primarily room-based and function-based approaches—along with practical tips and conventions for labelling and organizing group addresses in residential and commercial projects. 

Two approaches to Group Addressing

Room Based Group Addressing

This type of group address structure is focused on location, with the main group usually referencing a floor or an area. 

The middle group specifies the room and contains all functions relevant to that roomroom, meaning it is very quick and simple to program and test as everything needed for a room can be seen together. This is most suited to residential projects as the rooms define the functionality and layout of the building. It is also preferred by integrators with an AV background.

From the Room example - 1/0/10, 1/0/20 and 1/0/30 are switching objects for 3 circuits in the same room. 

Function Based Group Addressing

With a function based group address structure, the main group usually refers to the type of function, such a lighting, HVAC, blinds. This uses the Middle Group to assign the function such as switching, dimming and feedback with less regard for the building layout. This is generally more suitable for commercial projects with a large number of circuits and is preferred by integrators with an electrical or engineering background. 

From the Function example - 3/0/10, 3/1/10, 3/2/10, 3/3/10 and 3/4/10 are the switching, dimming, value and feedback objects of the same circuit. 

Group Address Labelling and Abbreviations

In either case the key is consistent use of numbering and nomenclature as this allows for an assumption to be made about the Group Address numbers once you get to know the scheme. 

There are also various naming structures for the individual group addresses. When using the group or bus monitor it helps to have as much information as possible and in a plain text format. The following information is most helpful: 

• Room
• Circuit Name
• Circuit Type
• Circuit Number
• Wiring Location
• Function

This can be seen in both the examples above.

Some common abbreviations used for the functions are:

• SW - Switching 
• DIM - Brighter/darker 
• VAL or VDIM - Value dimming 
• FB - Feedback 
• VFB or VALFB - Value feedback 
• SA - Switching actuator 
• DA - Dimming actuator 
• BA - Blind actuator 
• BI - Binary input 
• HA - Heating actuator 
• MAN - Manifold 
• RAD - Radiator 
• FCA - Fan coil actuator 
• KP- Keypad 
• LK- Light keypad 
• SP - Sensor plate 
• RTR - Room temperature rollover (mode change 
• PRS - Presence object to activate heating 
• WDW - Window object to set back heating 
• SET - Set point 
• SETFB - Set point feedback 
• IND - Indication 
• DIS - Disable 

Room or Location based model - In depth look

When using the room/location model of group addressing, it is worth bearing in mind that only 8 middle groups are available. This means that if there is an area with more the 8 rooms, then the area may need to be split over multiple main groups (see example below). 

In the example below, we also have a group addresses for whole room control, that are associated with multiple channels and can be used to turn on or off or dim all lights in a room at once. 

Having a clear structure for group addresses can speed up linking to channels as ETS will autofill with the next available address. It is also possible to select multiple group objects at the same time and link them all to the same group address with just a few clicks. 

The example below shows the channels of a dimming actuator and the group addresses that it is linked to. 

Planning your Group Address Structure

When using an external controller or visualization product, such as the Gira X1 or ABB Comfort Touch, it is important to add all group addresses that are likely to be used, not just those that are needed for native bus operation.  

It is far easier to do this at an early stage as opposed to adding them in as needed. It also makes testing much simpler when feedback objects are assigned.  

When using the standard 3 level group address structure, it is possible to have a total of 32 main groups, 8 middle groups and 256 groups. 

Group Addressing Summary

A well-planned KNX group addressing structure is essential for efficient programming, easier maintenance, and faster troubleshooting. Whether using a room-based or function-based approach, consistency in layout, naming, and abbreviation practices significantly enhances project clarity and scalability.  

Room-based structures are often best suited for residential projects due to their intuitive layout, while function-based structures can offer greater efficiency in larger, more complex commercial environments. Taking the time to properly plan your group addresses, especially when integrating with external controllers, will ultimately lead to a smoother commissioning process and a more robust KNX system. 

What next?

Read our blog about KNX Wiring & Topology or browse our other Essential Guides.

Looking for help with KNX System Design or KNX Training? Talk to our team on 03333 079 100 or email sales@ivoryegg.co.uk