I've included this photograph because of the glimpse offered of the ground floor of the stairwell. In this photograph you see it as a wood floor (with insulation underneath). Originally this was a stone floor. The idea was that during the day the sun would heat the stones and during the night the heat would be dispersed through the house. In practice this did not work. The house got so warm during the summer from the passive solar heating through the windows that any heat from the stones was not necessary. During the winter the sun, when it was not obscured by clouds, was low in the sky (and this on a piece of land with many mature trees) and was not able to heat the stones. If anything they just stayed cold which was not helpful at that time of year. So it was decided to put the wooden floor in with insulation underneath to create a barrier from the stone floor.