We often think of window design relative to the exterior of a house and focus on the process of sizing and arranging windows to make a pleasing facade. But the size, placement, and number of windows affect what a house feels like on the inside as well as how it looks on the outside. Here, I’ll focus on how the interior needs of a house impact decisions about window size, quantity, and placement. Remember, however, that making thoughtful decisions from both sides simultaneously is key to a design that is pleasing both inside and out.
Windows can provide a house with three things: light, views, and ventilation, though not all windows provide all these things. Different types of rooms need these qualities in different amounts, and those needs should influence the size, quantity, and placement of the windows in those rooms.
Public rooms call for generous windowsLiving, dining, and family rooms are sized to accommodate groups of people. There is little expectation of privacy, so these rooms can happily accommodate larger and more windows.
Because the tops of windows are usually aligned, often with a doorway, one way of introducing tall windows is to lower the height of the stool, commonly called the “sill.” Generally, interior stools of windows in public rooms are 30 in. or less from the floor. A taller window with a lower stool feels more gracious and appropriate in public rooms. Remember, though, that most building codes require tempered glass in windows less than 18 in. from the floor.
Light, views, and ventilation are enhanced by the placement of windows relative to other windows and doors (drawing right). Arranging windows so that light enters from two or more sides of a room makes an interior feel more spacious. It also provides cross ventilation, a wonderful attribute that’s especially appreciated in a room that often holds big groups of (potentially sweaty) people.