When I lived in London, I rented a flat that was in the loft of an old house.

There was no insulation in the sloped parts of the ceiling, only the flat middle bit had insulation.

Meaning winter was cold and summer was hot. In summer my ceiling was hot to the touch and in winter often my heating could not keep up. It would be running at full capacity and I could watch my thermostat temperature keep dropping.

I could keep my windows open all night and by morning it was still over 30 degrees inside, the heat would just never leave. I think because the wind would blow along the side of the house instead of directly at it so I got no airflow.

It still gets hot in my current flat, maybe 33 degrees but at least in winter it holds onto heat well. I can sleep with thin blankets.

Here is a photo of my thermostat at the peak I noticed.