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CASIENT

The system

One box, beside the bus you already own.

Casient does not replace KNX and does not ask you to remove anything. It is a sealed appliance that sits on the network, reads the installation you commissioned, builds a model of the building, and runs behaviour from that model — writing to the same bus, through the same actuators, with the same ETS project as the source of truth.

What happens, in order.

.knxprojingested once, off-sitelive bustelegrams, continuouslyModel of the housespaces · devices · capabilitiesBrick · SAREF alignedPolicies proposepre-heat railhold zone 3defer dishwashersuppress all-off…and 19 moreArbiter6 tiersthe busa real telegramthe logappend-onlyyour override re-enters as the strongest evidence

Precedence

Six tiers. A lower one cannot win.

Most automation resolves conflicts by whichever instruction arrives last, which makes behaviour a function of scheduler timing. Here the arbiter compares tiers before it compares anything else, so an efficiency policy has no mechanism by which to reach past a habitability constraint — not by convention, but structurally.

Why this is the licence to operate →
  1. 1

    Safety and statutory

    Smoke, water, gas, egress, electrical protection.

  2. 2

    Security

    Perimeter, access control, alarm state.

  3. 3

    Health and habitability

    Temperature bounds, humidity, air quality, refrigeration.

  4. 4

    Explicit human instruction

    What somebody in the house actually asked for.

  5. 5

    Comfort

    Light levels, pre-heating, the pleasant things.

  6. 6

    Efficiency

    Tariff shifting, solar alignment, load management.

Architecture

Four boundaries we cannot cross later.

These are the decisions that would require rebuilding the product to undo, which is the only kind of promise worth making about a device that will sit in your plant room for fifteen years.

The appliance is sealed

One box, one job. Minimal Debian, containers as systemd units, a hardware watchdog and a four-rung restart ladder. It is not a general-purpose computer and you cannot install things on it, which is the entire security model.

The ingestion tool never enters your house

Reading .knxproj files is an installer-side service. Your appliance receives only the finished model, as a signed bundle. A parser for arbitrary project files is not something that should live on a home network for fifteen years.

Remote support is granted, not held

We have no standing access. When support is needed, you grant a time-boxed session from the console in your own house, it appears in your log, and it expires on its own.

Licensing cannot reach the physical layer

An expired subscription degrades learning and remote support. It has no code path to a relay, a lock, a valve or a dimmer. This is enforced by process separation, not policy.

The stack

What it is built on.

Four components, none of them secret. You will see all of this during commissioning, so there is no reason to be coy about it beforehand.

Home Assistant

The device and integration layer runs on Home Assistant. It is what talks to the protocols, and it is the reason the long tail of third-party equipment — media, HVAC apps, streaming, appliances — is reachable at all. We pin the version, ship it as part of a sealed image, and take support responsibility for it; you never administer it and neither does the client.

The policy engine

Ours. The registry, the aggregators, the policies, the arbiter and the decision log are not Home Assistant automations and do not run as them. This is the part that is actually Casient, and it is where the behaviour a client notices comes from.

Debian and Podman

Minimal Debian host, containers as systemd units, hardware watchdog. Chosen over an appliance OS because a box in someone's plant room needs host-level control of restarts, power loss and storage health.

Your ETS project

The source of truth for what the building is. Ingested once, off-site, and never superseded by anything we hold.

Commissioning

It goes on after the bus works.

Casient is commissioned against a KNX installation that is already finished, tested and signed off standalone. That ordering is not a preference — it is what makes the failure mode true.

If safety or comfort behaviour were moved up into our layer to save ETS effort, the house would stop being independent of us, and the strongest thing about the product would quietly stop being true. So it is a condition of partnership rather than a recommendation: all of it stays in the bus.

The adoption path →

What it speaks.

KNX
Native, over KNXnet/IP. Reads and writes group addresses with correct DPT handling.
DALI
Via gateway. 2 gateways in the reference house.
Matter & Zigbee
For everything that arrived after the walls were closed.
Modbus TCP
Inverters, batteries, meters. Solar and tariff behaviour depends on it.
BACnet
Where the HVAC plant speaks it rather than a proprietary controller.
Modbus RTU
Where the plant predates Ethernet, via gateway.