But since hot air doesn't flow downwards, I don't bother closing my loft hatch as the sun goes up.
I opened the downstairs doors about 6am and got a strong flow of cooling air, closed the front about 10am when the sun moved towards it, closed the back about 2pm when the clouds cleared. It opens onto a shaded green area.
Looking at the nearby weather station reports, temp was 23C at 10am, and 25C at 2pm. Overnight temps were 17/18/19C, so consistently cooler than in the house, so continual convection flow, in through partially open windows, out through loft hatch. I can tolerate indoor temps of 25C, but dislike 30C or above.
If I had been going to work at 8am and back at 6pm the house would have been fresh all the time I was here. Not stifling, as if would be if shut up all day.