Interior Lighting for Designers

beam of sunlight on a task will provide
momentary change and relief; if it remains it
will soon cause visual fatigue and stress.
Daylight and view do not necessarily go
together and often are achieved through dif-
ferent building openings. The criteria for pro-
ducing a view to the exterior are different
from the criteria for producing good interior
daylight.
The more complex the view and the
more frequent the changes, the greater will
be our satisfaction. Although large windows
are sometimes desirable, people’s basic
need for a view of the outside can be satis-
fied with comparatively small openings.

Daylight Design

Window size and height above the work sur-
face are factors in daylighting design. Of
course, as the window becomes larger in
size, the amount of daylight increases. But
the height of the window is the more signifi-
cant factor.
The higher the window opening, the
deeper the daylight can penetrate into the
room, and if it is high enough, it may prevent
exterior brightness from causing glare. This

high-entry light is softened and spread by

proper design of the room surfaces.

Interreflections between these surfaces

cause the brightness patterns to become

more uniform; visibility and seeing comfort

are increased.

Windows and other daylight openings

that are set flush in a wall or ceiling produce

excessive contrasts between exterior bright-

ness and the immediately adjacent interior

surfaces. This contrast is often harsh and

uncomfortable.

A softer transition is achieved with the

use of splayed jambs, rounded jambs, and

deep window wells. Instead of the sharp

contrast between adjacent surfaces, these

designs provide a zone of intermediate lumi-

nance to soften the change (figure 5.1). The

jambs of the window become light-reflecting

shelves that reflect the light indirectly into

the interior. Other solutions include using

white paint around the windows or hanging

draperies or blinds.

For comfortable seeing, the luminance

ratio betweenfenestrationand adjacent sur-

faces ought to be less than 20:1. This ratio

is also desirable for the surface luminance of

INTERIOR LIGHTING FOR DESIGNERS

Figure 5.1Splayed and rounded window jambs soften contrasts.