Sure. I don’t have many enabled right now but some that I’ve used that are probably useful to others

I have a zigbee smart lock that was relatively cheap but didn’t have a sensor on it to detect if the door is open or closed, just a timer built in. To make the lock smarter so that it won’t attempt to lock if the door is open, I’ve used a $10 aqara sensors to detect if the door is opened or not and then combined those with the door lock to say, trigger a door lock after 5 minutes of the sensory closing, but only if the door isn’t opened again.

Another Aqara sensor automation that I don’t use any more as we moved to a house that has a carport rather than garage, but I used a contact sensor on my ‘dumb’ garage door to detect if the door was open or not. If the garage door was opened, the garage light would go on. Could do this other ways such as with motion sensors etc but unlike a motion sensor this would keep a light on until the door closed.

I have a robotic vacuum that I would automatically turn on when every person left the house. If someone was detected returning within a KM of the home, the robot would then return to the dock so it was out of the way when people got home. I really really loved this automation, but I haven’t used it since having kids 4 years ago as there has inevitably been too many toys etc that the vacuum would pick up now days. If your floor is relatively tidy but, it’s a great way to do a vacuum.

I haven’t explored it yet but Home Assistant pulls in my data from my solar panels and battery. In theory I could probably automate some of my appliances based on power generation or battery charge. Haven’t explored that fully yet however.

Those are some thoughts. Right now I use it mostly to bridge devices that otherwise don’t talk together or integrate with HomeKit. Haven’t played around with the automations for a bit, but meaning to go in and have a play with it more at some point. It’s a product I tinker with for a few weeks then let simmer for months before coming back too.

You can use it for the most basic of things and build from there. My first automation was turning off all the lights around my home at bed time (triggered by a button which makes it less automation and more remote control I guess). From there the bug bit me and I do all kinds of crazy stuff now.

The most practical is my load-shifting power automations. My power company has a rate plan that rewards you with really cheap power if most of the time in exchange for not using power during peak times. I selected this plan and automate a near-complete shutdown of the electrical systems in my home during peak times - the A/C goes off, the water heater goes off, the pool pump off, nearly everything except for lights. Total house power use during this time goes to like 400watts as a result. It has saved me hundreds on my power bill, even with adding an electric car that needs to charge every night!

The most magical is likely the automations around my bed. Both going to bed and getting out of bed are detected and magical stuff happens. When the first person gets into bed (either my wife or myself) almost nothing happens other than the lights dimming in the bedroom to get ready for sleep. Once the second person is in bed a bunch of things happen - all of the lights in the house go off, the doors lock (if they weren't already), the garage doors close (if they weren't already), the security system arms for "Home mode", the HVAC systems go into eco mode outside of the sleeping areas, and a toggle is set for "Sleep mode" that allows me to have other automations make decisions based on it (like if an interior motion sensor turns on a light during sleep mode, the light is turned on at a low dim mode). When the first person gets out of bed after our wake up time of 06:00 the coffee maker will start brewing. Once the second person is out of bed the sleep mode is disabled and most of the home systems return to normal.

Another favorite is the nightlight mode for my kids. Their bedrooms are on opposite ends of a hallway with a shared bathroom in the middle. During sleep mode, if one of them opens their door at night, the lights on their side of the hallway will turn on to a very warm color and very dim, but plenty to walk by. The bathroom lights also turn on dimly and everything automatically turns off a few minutes after motion stops being detected.

I've got tons of stuff related to motion detection for security and such too. It's really a sickness once you get into it. I can't stop sometimes... send help...

My cats like to look out our bedroom window in the morning. We have smart blinds. So I use an Ikea motion sensor to tell when one of my cats goes near our bedroom blinds and one of the blinds then opens just enough for them to look outside.

Another is we have indoor security cameras to spy on said cats when we're away. But when we come home, I use Home Assistant to turn the cameras to face the wall and when we leave, it turns the cameras to face the rooms.

My favourite one solved a long-standing argument between my wife and I. I like to keep my office slightly warmer than the rest of the house, and she hates wasting electricity by heating it when I'm not there. She would keep lowering the thermostat when I was not working (like on the weekends), and I'd come back on Monday and wonder why I'm freezing in front of my computer.

I solved it with Home Assistant and a smart thermostat. Now whenever my computer becomes active, it sets the thermostat to my favourite temp, and when it's asleep (or away) for more than 15 minutes, it sets it back to the "away" temp. Lights are also synchronized with the whole thing.

Home assistant isn't only for automations! I just use it as the smart hub for my house in general. I control all my lights and other smart home devices through the home assistant dashboard, it's just like having one centralized app instead of many individual apps for every smart home device.

I use the esphome intergration to make my own diy smart home devices, and so much more.

Really if you have any interest in a "smart home" or using any smart home products on a reoccurring bases I'd say home assistant is worth getting into.

In my case: door is unlocked + nobody in the hallway -> notification. State of the door lock accessible via app is nice by itself (did I close the door?).

Generally anything you want to do at home, but often forget.

There's a thread full of people's favourite automations here: https://discuss.tchncs.de/post/467348

It's not the most complicated, but it's nice.

Ceiling motion sensor above the stairwell leading to second floor that activates hue bulbs in the upstairs hall. Depending on the time of day it turns on for different lengths of times/brightness and at night for ~2 min to red to allow easy travel without upsetting eyes adjusted for darkness.

That and a similar one that we activate via our echos called "Bedtime for babies" that dims all the lights to have our little one start winding down.