Windows come in all styles, types, shapes and sizes, but unless you’re building a new house, all of the above are largely predetermined. There are of course some exceptions. Perhaps a previous homeowner replaced the original windows with units that are historically inappropriate or inferior. Or maybe you’re adding a family room at the back of the house, where it would be okay to deviate from the double hung windows in the front; in this situation, you might decide to use casements. Sometimes a homeowner will want to increase or decrease the size of the window being replaced, but if you’re like most homeowners, the real decisions will have more to do with energy-saving features and ease of maintenance.