Loud cracking in the evening. What is the cause?

Hello everyone,

I am slowly at a loss. In the evenings between 9 PM and 3 AM, there is a cracking sound in our house. The noise is a single, loud crack. Always about once every hour. Sometimes only every 2 hours. At the beginning, almost precisely on the minute. Every day at 8:44 PM I stood somewhere in the house to locate the noise. Unfortunately, without much success. We have a radiator in the converted attic. I suspect it. Could that be possible? But it has always been turned off.

Meanwhile, the noise is time-shifted. Today, for example, at 8:49 PM, 10:03 PM, and 12:07 AM. I also suspected the roof beams, but this cracking really only happens in the evening and always sounds the same. Because of the same time at the beginning, I quickly ruled them out.

We have various actuators installed, all of which I have already turned off. The problem still exists. We still have a ventilation system. I actually haven’t turned it off yet, but what should be cracking there? Animals are also ruled out in my opinion. Otherwise, you would hear some rustling or something similar, right?

I am open to all ideas. I am sitting in front of the radiator again, waiting for the next round...

... a house is working. It sinks, the screed bulges, the timber dries... and with a temperature change, everything even more so.

I know all that. And I also partly perceive it acoustically. But this cracking is different.
However, it only occurs in the evenings.
It is always the same sound. Not quieter or louder.
In the first few days, it was always at exactly the same time.
even now it always starts for the first time between 8:45 and 9:15 PM...

Gutter or window cooling down?

Main fuse out, then you know whether it was an electrical device, like air conditioning, heating, or something else.

Is the cracking also on cloudy or rainy days when the house does not heat up and expand as much compared to days with bright sunshine?

Sounds like windows to me. Since we currently have almost the same weather every day, the times could also match.