1 100 m² where the client reassigns his own switches — without calling us
- Floor area
- 1 100 m²Floor area
- Rooms
- 35Rooms
- Isolated segments
- 4Isolated segments
- Devices
- 207Devices
Overview
A 1 100 m² residence over three floors plus landscape, 35 rooms, handed over in 2023. Lighting, blinds, underfloor heating, air conditioning and landscape lighting. The client did not want KNX pushbuttons, and he wanted to be able to change what his switches do himself. That requirement decided the architecture — the equipment followed from it, not the other way round.
Challenge
The requirement sounds small and is not: a client who can reassign his own switch keys is a client who does not need to call anyone to change his mind about a room. Almost nothing on the market is built for that. Bus pushbuttons are configured in the manufacturer's tool, which means the vendor's software, the vendor's licence and, in practice, us.
The second problem was scale of a different kind. Thirty-five rooms is too many for a single "home" in the Apple Home app: the list stops being navigable and people give up looking for the room they want. An interface nobody opens is worth exactly as much as no interface.
And the two problems pull in opposite directions. Making the house easy to re-program pushes towards one central place to change things; making it navigable pushes towards splitting it up.
Solution
The house is built as four isolated Modbus segments — three floors and the landscape. Each segment has its own Tact Automation controller, and each controller has its own bridge into HomeKit. In the app the house appears as four separate homes, each one small enough to navigate.
The isolation is not only electrical. Segment, controller, bridge and "home" are the same boundary drawn at four levels, which means a fault, a restart or a firmware update stops at that boundary instead of taking the house with it.
Key assignment lives in a web interface of our own, not in a vendor tool. The owner opens it, picks a key and chooses what it does. No licence, no seat, no appointment with an integrator — which is the whole point: this site is the argument that "no vendor lock-in" is a fact here and not a sentence in a proposal.
The field layer is deliberately dumb: six-channel relay modules for lighting, landscape, underfloor heating and heating circuits, three-shutter modules for blinds, fourteen-channel dry contact modules for the switches themselves, and CoolMaster for the air conditioning. All the logic sits in the controllers, where it can be read and changed.
Systems & Technologies
Built in-house
In numbers
- Rooms across four segments
- 35Rooms across four segments
- Field devices
- 207Field devices
- Controlled outputs
- 418Controlled outputs
- Switch inputs
- 252Switch inputs
- Temperature and humidity sensors
- 90Temperature and humidity sensors
- Controllers, one per segment
- 4Controllers, one per segment
Project Details
- Object type
- Private residence
- Area
- 1 100 m²
- Commissioned
- 2023
- Technologies
- ModbusTact Automation
Discuss a Project
Result
The owner changes what his switches do himself. That is the sentence the rest of this page exists to support, and it is the difference between being handed documentation and being handed control.
Seventy temperature sensors across thirty-five rooms is roughly two per room — the same reason the 350 m² house averages several sensors per zone rather than trusting one point on one wall.
What remains unresolved
Splitting the house into four homes cost something real, and it is the direct price of the navigation it bought. A scene that spans floors has no natural place to live: "everything off" is four actions in the app rather than one, because the app has no concept above a home. We handle cross-segment scenes in the controllers instead, which works but is no longer something the owner can rearrange himself in the web interface.
The same boundary that contains a fault also contains a habit. Anything the household wants to behave identically everywhere — a single evening scene, one holiday mode — has to be maintained in four places rather than one.
There is no ETS project here and no group address export to publish, because the object does not run on KNX. What can be shown of it is the architecture, not a searchable address tree, and that is a genuine gap next to our KNX cases.