“Let the sunshine in” may make for a catchy song, but for homeowners concerned about energy use, comfort, and preservation of fabrics and finishes, it’s more complicated than that. Letting the sunshine in can reduce energy consumption in cold climates, but it can increase it in warm climates; it can warm an otherwise chilly interior, but it can make an already warm interior unbearable; it can bring light into a dark room, but its UV-rays can damage furniture and floor coverings.
Homeowners have both interior- and exterior-shading options to ensure that their windows are net-positive features. While interior choices such as blinds and curtains are most common, exterior options have two advantages: They stop heat from entering the house in the first place, and the choice of interior window treatments, or whether to have them at all, can be based solely on aesthetics.
Some exterior-shading options make sense only for certain regions, either for practical reasons or because they fit with the predominant architectural styles.