dieter aschenbrenner

I'm a builder, not a registered architect.
When I mentioned flat ceiling, I was referring only to the ceiling, not the roof. The roof could be pitched, sloped, or whatever.
I agree that high windows would lose more heat, which is why I think perhaps there is a way of determining just how much. Perhaps there's some software that could tell you how much heat is gained by the high windows onto a thermal mass wall, how much would be radiated from that wall, for how long, and how much heat would be lost with high windows and high ceiling, versus low windows and low ceiling.
Or maybe two neighbouring houses comparing the difference

I do house plans and am just wondering whether these high ceiling skillion roofs with high north facing windows is really better, since it is more difficult to heat a room with a high ceiling. I understand the high windows could be double glazed with internal blinds, and you have the benefit of heating up an internal thermal mass wall, but are the benefits really worth it? Say compared to a flat ceiling say 2700 mm high with north facing windows on the north wall, heating perhaps just a slab on ground.
Does anyone know any way to prove which is better in keeping the place warm in winter? Especially if the solar gain is not sufficient at times and one would need to add their own heating.

High ceilings can be a bonus in Summer to keep the place cool, so perhaps someone knows how to include this in their calc's too?

I'm assuming North windows being in the south hemisphere.
Also, with a skillion roof, if the higher wall is on the north side and the roof slopes towards the south, it would be more difficult to install solar panels on the roof and get adequate sunlight in winter, correct?

One more thing to consider in the calculations... if the majority of the radiant sun heat comes from the north, a south sloping roof would perhaps reflect heat easier than say a north sloping roof (if the south wall was the highest wall)