I was reading an article about house design and passive solar gain i.e. using the sun's energy without doing solar panels.

It said that in the winter mornings, open all shades, curtains (anything blocking sunny windows) especially on the south side. And when building a house think about those south side windows - lots of them for areas where you use lots of heat - less where AC is your primary issue.

For AC days, close as many drapes/blinds on those sunny windows to minimize "solar gain". Or at minimum use sheers to diffuse the light.

And soon as the sun sets, shut all those blinds, curtains etc. to retain the heat. Use insulating drapes and shades.

And for airflow when you want the windows open, create cross drafts. The article said that houses in the pre-AC days used to have rooms off of long halls with windows at both ends of the hall and the bedrooms opposite each other to create another cross draft by opening the windows in the rooms as well.

The article also talked about designing houses with windows such that you don't need to flip on any lights during the day.

Also, dark colored paints are better for houses where heating is the issue, light colored paints for AC. Think of how hot blacktop is in the summer vs. cement. Dark colors soak up the heat.

Also, the article talked about shade trees. A tree that drops its leaves in the fall can shade the house in the summer, yet let the sun through in the winter.

Something to think about ....