Some folks in the Intermountain West use “heat pumps.” I don’t know much about them, but it may be what you’re looking for. Heat in the winter, cool in the summer and the rest of the year is “comfortable.”
The heat pump is the next step in what I was describing above. In Sionnsar's situation, the temperature underground is always cooler than that in the house. (Science based on the proverbial well-digger's butt.)
A heat pump makes it, well, professional. You're actually pumping heat around. Out of the house in the Summer, and back into it in the Winter.
What makes it efficient is that you can use the same heat over and over. You don't have to generate new heat.
Using last Summer's heat for Winter warmth, or last Winter's coolness for Summer comfort ought to appeal to the Scot in any one.