Another point the make is the angle of the building to the sun. Which also has, according to some research, some things to do with the equinox, but again, it's about averages. I still don't consider my knowledge of this complete, just because I meet folks with such extreme views opposite to each other. I myself would love to read what others here on Permies forum think about building/roof angle to equinox. I think, once you get past 45 degree roof pitch you are in a close enough range to be efficient. Then I just start looking a function of the roof to shed precipitant, ease of construction math and aesthetics. Whether you go for a 3/4/5 triangle (53.13010235º) or an Isosceles triangle (60º), I don't think at those pitches the statistical heat gains are that different, that is why I just go with 53º.
I think I saw somewhere that you want the angle to be the latitude plus 10 degrees? So, if you are at 33º north, then your angle would be 43º ?
Thanks for good questions, you are keeping me on my toes and making me feel like I teaching Science again. I have always reversed these in my head, (dyslexia is a pain in the back side,) the vernal equinox, summer solstice, fall equinox, and winter solstice. Thanks for catching that.
I might be wrong but the day when I get less sun is in the winter solstice (not equinox), right?