The leaves keep the sun off in summer, but fall off so the sun shines in when it’s cold out. It also works with vines on a trellis a few feet in front of the windows. Anything hat keeps the sun off the glass will work better than trying to block the heat from the inside.
We’re fortunate enough to have evaporative coolers, so we only run the A/C during the hottest, most humid parts of the summer. The heat is set @ 62-64 all winter, but it almost never comes on. Once in awhile it will get down to freezing & we’ll wake up glad we leave it on.
I do wish we hadn’t gotten house fever when we bought this place, though. The long sides of our house face east & west, along with most of our windows. We get terrible heat gain on summer afternoons. So far we’ve extended our porch roof & planted some desert trees on the west site, and it helps a little. I’m jealous of the old high end homes in the middle of town that were built before A/C. Thick walls, huge, south facing windows, big, shady trees, sleeping porches & deep overhangs. If we ever build a place out here, we’ll be stealing a LOT of ideas!