homeassistant

KNX is indeed a protocol, but there is a whole multi - manufacturer ecosystem around it. It is mostly used in the commercial space. It is literally the ultimate smart electricity ecosystem for reliability.

Everything that I did is done in the electrical box so you buy traditional push button switches for the walls with very thin, cheap cable, and then your lights as normal.

It is wired originally with twisted pair bus that delivers power and data. They branched out also into wireless products also now using 898MHz bands (same as zwave).

The protocol is very tightly regulated but everything is guaranteed to work. It isn't wireless so it doesn't have shitty mesh problems like zwave and ZigBee have with many devices. You don't get bad device behaviors and disconnects with power outages. There are no shitty batteries to replace (and no fibaro zwave devices having ridiculous battery drains when outside of a +/-10C range from 20C).

It will simply work and keep working for your lifetime, unlike many or most ZigBee and Zwave devices.

Unlike Starfighter says, It actually isn't that expensive for basic home users. if you do it correctly and don't go for "everything being LCD panels". It is much much cheaper than retrofitting every socket with ZigBee or zwave smart switches. I am fully stripping and renovating my house and it is literally about the same price as doing everything with modern teleruptors, with 10x the functionality. If you include the license, then maybe 10% more expensive.

It cost me literally 1400€ 32 switches, 16 circuits of on/off lights and fans (or I could use them for roll blinds), and 4 dimming circuits, plus temperature and humidity sensors to smartly turn on bathroom fans. It is €30 for every Shelly wave module which would be 1000€ just for the switches alone with no dimming or sensing. Plus if you are already rewiring you house, you get to save a shit ton of money using small gauge cable with potential-less contacts.

Don't get me wrong, zwave is great, but KNX is absolutely king at only a marginal price premium (for standard home users, commercial focused HVAC controllers and such are expensive as hell)

Edit: also one thing to note is that all UI elements of KNX through pretty much all the manufacturers look like they are from 2010 or earlier (and they often are). I much prefer other options or a Home Assistant tablet or something.

Mostly its really fucking expensive. Usual applications are central control of heating and window blinds in large office buildings.

Part of what drives the price is that ideally it's all hard wired.