The heat definitely rises because the stairs are open in the sitting room. This is great in winter because the log-burner heats the whole of the main part of the house. In summer it doesn't help. South-facing window shuttered and anti-solar blind, arrow slits in north wall open all the time. No windows to east or west except veluxes in the sides of the roof (below the boarded, insulated attic bit) which have high-quality blinds that really don't seem to let any heat in.
Space between ceiling and bedroom floor has thick layer of centuries of dirt, grain and mice (little mice with clogs on). Three foot thick stone walls, plus insulation, plus plasterboard.
Not a mansion, but an ancient, rambling old stone farmhouse. I suspect we won't solve it!