Insulation only works till the building is heat soaked then it makes it slower for the building to cool down and our houses are typically brick which holds heat

Insulation only works till the building is heat soaked then it makes it slower for the building to cool down and our houses are typically brick which holds heat well, uk houses have low airflow because it’s cold and wet much of the time so in summer the issue is that heat gets trapped in the day and we can’t get it out at night. It’s currently about 6 degrees warmer in my bedroom than outside but with no wind I struggle to get the heat from inside to outside.