Bragging time. I might even have bragged about this here before; I forget. But I wanted to brag about it some more anyway:

Our kitchen has a kind of moldy smell in some of the cabinets. Soon after we moved in, I installed an air quality sensor and a couple dehumidifiers, hoping to keep the kitchen drier than it is naturally. The problem is, the dehumidifiers are pretty loud, and people don't like having them on.

The dehumidifiers are "smart" (i.e. vulnerable to hackers building botnets, though that's not relevant to this story), so my initial response was to just schedule them to turn off during the day. But (a) then they're not running most of the time, and (b) it turns out that people are annoyed by them nearly any time of day: some people use the kitchen early in the morning, some people use it late at night.

After a few rounds of trying to find a good schedule compromise, I almost gave up and figured this had all been kind of a waste. But then I had a micro-epiphany: don't try to guess when people will be around; just measure it!

I bought some presence sensors, and a raspberry pi to run HomeAssistant, and spent about 20 minutes hooking them all together. So now, the dehumidifiers run 100% of the time except when someone is present. I was kinda skeptical that this would work reliably; I've done enough robotics projects to know that building solid electromechanical systems is not easy.

But it's been running for a month now, and as far as I can tell, it is 🤌 perfect. As soon as I come into the relevant part of the house, I hear the machines shut off. Every time. And they don't start again until I've left. It's so great, and I get a little rush of pride every time.