My Smart Home Is Haunted, Says the Data

I approached my haunting like a bug report, because that is what I am — a data engineer, professionally allergic to vibes. My flat had 'a feeling,' the cold spots and the sense-of-presence that every old flat has, and my girlfriend was unnerved by it, and I decided to do the loving, insufferable thing and PROVE IT WAS NOTHING with data.

I instrumented the flat like a lab. Temperature sensors in every room, humidity, a couple of cheap infrared arrays, motion sensors, door contacts, power draw, the works, all logging to a database every few seconds for a year. My hypothesis was draughts and pipe cycles and the boiler. I expected to hand my girlfriend a dashboard and a smug little talk about confirmation bias.

The data did not cooperate with my smugness. Buried in a year of logs, once I actually did the analysis I'd been putting off, was a pattern too clean to be noise. Nearly every night, clustered tightly around 3:33 a.m., a coherent thermal anomaly — a localized cold mass roughly the volume of a person — appeared in the hall and MOVED. Room to room, in sequence: hall, living room, past the kitchen, stopping in the doorway of the spare room. The infrared arrays caught it as a person-shaped cool region with no corresponding motion-sensor trip, no door contact, no power event, no open window (I logged those too). A cold, person-sized thing that walked my flat nightly and tripped nothing that requires a body, on a schedule accurate to a few minutes, for a year.

I have the heatmaps. I've animated them. Watching a year of nights compressed into thirty seconds — the same cold shape, the same route, the same 3:33, the same pause at the spare room — is the single most frightening thing I have ever generated in a code editor, and I've seen production databases delete themselves.

I did not give my girlfriend the smug talk. I gave her the animation, and we sat in silence, and then she asked the question I'd been avoiding: what's special about the spare room, where it always stops? I checked the flat's history properly for the first time. The spare room was, in the previous layout before a conversion, the main bedroom.

We still live here. I've kept the sensors running — I can't not, now; it would feel like looking away. The pattern continues. 3:33, the same route, the same pause where someone used to sleep. I've stopped trying to debug it. Some processes aren't errors. They're just running.