I see other folks have mentioned it but most everything actually effective needs to be done at the infrastructure leve of your home. I lived with my brother that had a split leve basement type thing. So first floor in the front had the main rooms while the bedrooms where half a floor up in back with a basement half a floor below. The basement also mostly faced south for its half windows and the bedrooms were built out further than the basement such that those where shaded by that and further there were trees in the back yard that gave more shade. There was also a crawlspace under the first floor main level that was accesible from the basement. Anyway the basement could be way cooler. Like not just a little but over ten degrees easily. You could get it even a bit cooler by opening the crawlspace access. Did nothing for humidity though.