ᐅ Loud cracking noises in the evening. What could be the cause?

Hello everyone,

I’m starting to get puzzled. In the evenings between 9 PM and 3 AM, there’s a cracking noise in our house.
It’s a single, loud crack.
Almost every hour, sometimes every two hours.
At first, it was almost precisely timed. Every day at 8:44 PM I stood somewhere in the house trying to locate the sound. Unfortunately, without much success. We have a radiator in the converted attic. I suspect it might be that. But it’s been switched off all along.

Lately, the noise occurs at different times. For example today at 8:49 PM, 10:03 PM, and 12:07 AM.
I also suspected the roof beams, but this cracking only happens in the evening and always sounds the same. Because it was at the same times at the start, I quickly ruled that out.

We have several actuators installed, all of which I have already switched off. The problem still persists.
We also have a ventilation system. I haven’t turned that off yet, but what would cause cracking there?
I don’t think it’s animals either. Otherwise, you’d probably hear some rustling or similar, wouldn’t you?

I’m open to all ideas. Sitting by the radiator again, waiting for the next occurrence...

... a house settles. The screed bows, the timber dries... and all of this is much more pronounced when temperatures change.

I know all that. And I can partly hear it acoustically. But this cracking sound is different.
It only happens in the evening.
It is always the same noise. Not quieter or louder.
In the first few days, it was always at exactly the same time.
Even now, it starts for the first time between 20:45 and 21:15 (8:45 and 9:15 PM)...

Gutter or window cooling down?

Main fuse off, then you will know if it was an electrical appliance, like the air conditioning, heating, or something else.

Does the cracking also happen on cloudy or rainy days, when the house doesn’t heat up and expand as much compared to days with strong sunshine?

Sounds to me like it could be the windows. Since we have almost the same weather every day at the moment, the timing could also fit.