Windows provide a connection with the natural environment and a relief from typical interior spaces. An enormous amount of information can be gathered by a simple glance out a window: the time of day, weather conditions, orientation, and the coming and going of other people. Views that are highly valued, such as views of oceans, lakes, trees, or mountains, often involve subtle movement and changes in light throughout the day, which can be both mentally restful and stimulating. Glimpses of familiar scenes or landmarks give a sense of place in the environment and within a building.
Using one larger window (or group of windows) instead of several smaller, scattered windows can have a powerful effect by visually connecting indoor and outdoor spaces. The picture windows make it possible to have a wide view without the distortion of many smaller windows. Sliding glass doors provide an even greater sense of openness with the possibility of floor-to-ceiling and wall-to-wall glazing. Creating a sun room that has glazing on two or three walls (and sometimes the roof as well) results in a space that feels as if it is at least partially outdoors.
Using Windows for Security and Surveillance
In addition to providing attractive views, windows allow visual and verbal communication between the inside and outside of a home. From a window, you can see who is approaching your house, if the neighbors are home, or when the kids arrive home from school. Parents have always valued windows as a way to monitor their children playing outside. The window at the kitchen sink that allows supervision of the backyard while doing kitchen work has become a common pattern in the home-building community.
A window must provide for just the right level of privacy for the inhabitants. A window is one of the main filters between our private world and the public realm beyond. The careful location of a window can resolve many privacy issues: a small window or a window placed high in a wall will restrict the view to the interior, while allowing a view of the outside.
Tinted or reflective glass can provide some degree of privacy, but its effectiveness depends upon a bright exterior and a dim interior. At night, when the relative brightness is reversed, tinted glass no longer offers much privacy. Frosted glass, textured glass, glass block, and stained glass can prevent a full view from the outside while providing daylight, but they just as effectively prevent a view to the outside. Curtains and blinds allow a full range of individual control, and are the primary way most people create the right level of privacy for their homes to accommodate changing privacy needs.
After many years of development, various switchable window technologies are now available. There are two basic types of switchable windows—passive devices that respond directly to a single environmental variable such as light level or temperature, and active devices that can be directly controlled in response to any variable such as occupant preferences or heating and cooling system requirements. The main passive devices are photochromics and thermochromics; active devices include liquid crystal, suspended particle, and electrochromics.