Daylight is inextricably linked to windows and openings within the exterior envelope of a building. The two cannot be separated under typical design approaches, although it is technologically possible to bring in daylight without win- dows through the use of light pipes and other strategies.
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Figure 5.9 illustrates a case where sunlight is brought into an underground research office, located about 100 feet below ground on the campus of the University of Minnesota, using a light pipe system. This system relies on a mirror located on the top of the roof and housed within a glass box ( Figure 5.10 ). The mirror sends light to the underground space through a simple shaft opening within the building.
The idea that people prefer to live and work in buildings that have windows is generally well accepted and widely documented. The benefits of windows were demonstrated in a study in Washington, DC by the Center for Building Performance of the US Department of Energy (Hartkopf et al ., 1994). On average, major health complaints were between 20% and 25% lower for persons close to an exterior win- dow compared with those who worked in the interior core, without access to view and daylight. People often add sky- lights to their homes just to have more natural light because it makes them feel better. Windows play several roles and have more than one effect on a room and its occupants.
The changing character of daylight adds a dynamic qualita- tive dimension to the ambiance of the room that is not easily achievable with an electric illuminant. Windows allow diffuse daylight and sunlight inside a room while providing views to the outside, thereby adding a sense of openness, spacious- ness, and orientation. Because of the technological advances of the last five decades, we are able to design buildings with large glass faỗades that permit daylight to enter and allow Figure 5.9 Sunlight brought into an underground office 30 meters below ground on the campus of the University of Minnesota (photograph:
M. Boubekri).
views to the outside. On the other hand, these same techno- logical advances gave rise to long-spanning structural sys- tems and large floor plates that pushed many workstations towards the inner core of the building and away from the exterior walls. Even with glass curtain walls many employ- ees are located far from the peripheral walls with neither the daylight nor the views. Even buildings with many win- dows house workers who do not benefit from these ameni- ties ( Figure 5.11 ). The importance of the connection with the outside world can be observed in the behavior of people Figure 5.10 Mirror collecting sunlight and sending it to an underground office 30 meters below ground on the campus of the University of Minnesota (photograph: M. Boubekri).
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who live and work in windowless spaces. They appear to use twice as many visual materials to decorate their workstations than do their counterparts who have windows. Landscape scenes and nature-related themes seem to be the preva- lent content of these visuals, an indication of a need to con- nect with the natural world (Heerwagen and Orians, 1986).
Dissatisfaction levels run very high among 90% of workers in windowless offices. About half of the employees surveyed felt that windowless environments affected them and their work negatively (Ruys, 1971).
Some countries have assumed a forward thinking, pro- user approach by recognizing the importance of windows.
The Netherlands, for example, now requires that buildings be designed so that all occupants are no more than 27 feet from a window. In the majority of countries, however, day- light and views take a back seat to other considerations such as economy. For most building codes worldwide, the func- tion of windows is to allow smoke to be vented out in case of fire and to provide escape routes for people in case of emergencies, rather than to bring in natural light. Almost all building codes do not require windows to bring in a certain level of daylight into the building.
The minimum size of a window needed to fulfill satisfac- torily a connection with the outside world has been the sub- ject of a major study in the United Kingdom (Ne’eman and Hopkinson, 1970; Ne’eman and Longmore, 1973). These Figure 5.11 An office building in Montreal, Canada, with windows but where most workers don’t have access to views to the outside (photograph: M. Boubekri).
researchers found that a window 11 feet in width would sat- isfy 85% of the room occupants. No mention was made about window height, however. The deciding factor for what should be the minimum size did not seem to be dictated by the lumi- nance (or brightness) of the window or by how much daylight it allowed in if the room had sufficient electric light, which was the case in this experiment. The amount of visual infor- mation contained in the view appeared to be the most sig- nificant factor. The important criteria seemed to be whether the visual information the window provided was intelligible and how complete the information about the world outside was. A window that was too small to provide complete visual information was much less desirable. Near objects, such as buildings, required larger windows than did distant objects ( Figures 5.12 and 5.13 ). Attention to the outside world proved an important ingredient to relieve a sense of enclosure.
5.3 PSYCHOLOGY OF LIGHT AND PRODUCTIVITY