When a window is placed adjacent to the side wall of a room or abuts the ceiling, the entire wall or ceiling surface reflects the available daylight into the space, making it appear bright and cheery. If the same window were placed in the center of the wall, without the surrounding perpendicular surfaces to reflect the daylight, the room would be significantly darker. The wall area surrounding the window would also be significantly darker.
Grey Crawford When a window is placed adjacent to the side wall of a room or abuts the ceiling, the entire wall or ceiling surface reflects the available daylight into the space, making it appear bright and cheery. If the same window were placed in the center of the wall, without the surrounding perpendicular surfaces to reflect the daylight, the room would be significantly darker. The wall area surrounding the window would also be significantly darker.

All too often, a house plan is selected based on interior requirements and the appearance of the front façade. Only occasionally is the plan tailored to position windows so that they take advantage of special features of the site. There is so much more that a window or set of windows can do for a space and for the house as a whole. From the exterior, the arrangement of windows can give the home much of its personality as well as a sense of integrity, while from the interior, each window can be placed to maximize the amount of light and view for the space it opens into. The relative comfort of a room can be dramatically affected by the height of the windows off the floor. There's nothing more frustrating than sitting down at an informal eating area, for example, and finding that the windowsill is located just high enough that it obstructs the view to the garden beyond. My rule of thumb is to make the windowsill no more than 2 feet 4 inches off the floor for living areas and bedrooms where there is a significant view beyond. At this height, you can easily see out when sitting on a chair.

Adapted with permission from Home by Design by Sarah Susanka, published by The Taunton Press (2004).