What is KNX?

KNX is the open, worldwide standard for home and building automation. It is the common language that lets a light switch from one manufacturer dim a luminaire from another, while a third company's thermostat reads the same presence sensor — all without a proprietary gateway in the middle.

Formally, KNX is standardised as ISO/IEC 14543-3, the European standard EN 50090, and the Chinese standard GB/T 20965. It is maintained by the KNX Association, a member organisation of roughly 500 manufacturers.

Why a standard matters

Before KNX, building automation was a collection of islands. Each vendor had its own wiring, its own tool, and its own logic. Replace the vendor and you replaced the building's nervous system.

KNX was created to end that. Its promises are:

• Manufacturer independence. Any KNX-certified device works with any other KNX-certified device. Certification is mandatory and tested — the logo is a guarantee, not marketing.
• One tool. Every project, regardless of which brands are in it, is engineered with ETS.
• Longevity. The standard is backward compatible. A device commissioned in 2005 still speaks to one made in 2025.
• No single point of failure. Intelligence is distributed across the devices, not concentrated in one controller that can brick the whole building.

For a building owner this is the important part: KNX is an asset that outlives the integrator who installed it. That is exactly the problem KNX Clarity exists to manage — see Escrow & transfers.

A short history

KNX did not appear from nothing. It is the convergence of three older European bus systems:

Predecessor	Origin
EIB	European Installation Bus (1990, ABB et al.)
EHS	European Home Systems
BatiBUS	French building bus

In 1999 their organisations merged into the KNX Association and unified the systems into one standard. KNX is fully backward compatible with EIB — you will still see "EIB" stamped on older hardware and in older documentation. For practical purposes, EIB and KNX are the same bus.

What KNX controls

A typical KNX installation touches most of the building's services:

• Lighting — switching, dimming, DALI gateways, scenes.
• Shading — blinds, shutters, awnings, with wind/sun automation.
• HVAC — room thermostats, valve actuators, ventilation.
• Energy — metering, load management, PV and storage.
• Safety & access — presence simulation, alarm integration, door/gate control.
• Visualisation — touch panels, apps, and logic modules tying the above into scenes and schedules.

What KNX is not

• It is not a product — you cannot buy "a KNX". You buy KNX devices and engineer them into a system.
• It is not the internet of things. KNX is a wired (or KNX-RF / KNX-IP) field bus with deterministic behaviour, not a cloud platform. It can be bridged to IP and the cloud — which is precisely the boundary KNX Clarity sits on.
• It is not plug-and-play. A KNX installation has to be engineered: addresses assigned, parameters set, group addresses linked. That engineering is the .knxproj KNX Clarity stores and versions.

Where KNX Clarity fits

KNX Clarity is not part of the bus and never talks to a device. It is the system of record for the engineering: the project structure, the devices, the group addresses, the ETS versions, and the human history around them. Think of the Academy as "the building side" and the User Guide as "the KNX Clarity side".