I've seen houses with big rocks in them before, I hadn't connected that they might have been acting as slow release heat sinks. I also hadn't thought about the role of deciduous trees giving shade in summer and letting light through in winter.
Interesting.
In the British Isles there's just so many old houses with terrible insulation, it's quite a chronic problem. And with the cost of heating skyrocketing I think it's becoming ever more important to get these considerations right. I think I'm going to try my hand at an aluminium passive heater the next time I'm home! Cheers