Perhaps not pertinent, but the evolution of the sash window to provide air circulation has always impressed me: https://en.wikipedia.org/wiki/Sash_window https

Perhaps not pertinent, but the evolution of the sash window to provide air circulation has always impressed me: https://en.wikipedia.org/wiki/Sash_window https://en.wikipedia.org/wiki/Sash_window By opening at the top and bottom it lets hot air out, and in doing so lets cooler air in below setting up a circulation. I just liked how an idea that must be a few hundred years old has evolved into a useful design.