one of my room is actually on building corner and it actually has two on that corner and each of them are on opposite walls on the corner: as a result, it actually gets sunlight from sunrise to sunset. That means it can get prohibitely hot during summer times. Currently painted with light color I am thinking to re-paint walls with darker color. Will it help? I think so, just because it seems like darker gives a feeling of cooler. There is an issue of darker color surface receives more light than light color (specially true in terms of clothing: you wear darker and you feel hotter) but in terms of wall color i think it is opposite and most of sunlight does not shine on the walls.