During the week I live alone in an apartment in Tokyo. Coming home to a cold apartment during the Winter or a hot apartment during the Summer was always a pet peeve of mine. My air conditioner has a timer on it, so I could always set that, but my schedule is so unpredictable that solution is not ideal.
I solved this issue with a product I found on Aliexpress. The product is known as the “Black bean”, or more properly, the “Broadlink RM Mini3” . When I first bought mine, it was only about USD $10, but they seem to have almost doubled in price since then.
https://www.aliexpress.com/item/32729931353.html?spm=2114.12010608.0.0.5ee01c24aKsgYa
Anyway, this is basically an infrared remote control that can be taught codes to emit. Furthermore, it hooks to your wi-fi network, so you use an app on your phone to control it. It also has a feature that relays commands from the cloud, so you can control the infrared remote commands from anywhere.
So, once I got this set up, I could turn on my air conditioner/heater when I leave the office, so by the time I arrive at my apartment 30 minutes later the temperature is comfortable.
I am still hoping to somehow connect it to IFTTT and build a fence around my work building, so that I can set it to detect when I leave the vicinity of work at the end of the day, it will automatically turn on my air conditioner/heater. (I still forget to turn it on about half the time.)