Interior Lighting for Designers

To avoid distracting brightness variation
in VDT screens, keep the variation in ceiling
luminance to a ratio of less than 4 : 1. In
addition, limit the average luminance of any
2 ft × 2 ft area of the ceiling to less than
850 cd/m^2 , measured at any angle. Apply
this same limit to windows, walls, and parti-
tions that will be reflected in the VDT screen.
The diffuse light from indirect systems,
however, reduces our sense of visual clarity,
depth perception, and sense of orientation.
This lack of highlight and shadow is miti-
gated by a greater use of surface color, wall
lighting, or object lighting; these techniques
add visual interest, thus enhancing percep-
tion of the environment.
Some indirect luminaires incorporate a
luminous element that is visible from below.
This is psychologically beneficial because
people feel more comfortable when they can
identify the source of light. This visible lumi-
nous element also increases the perception
of brightness in a space and introduces
visual highlight into a shadowless environ-
ment.
In a small office, only part of the ceiling
will be reflected in the VDT screen. Here, it is
the walls that are of concern. The walls of a
small office must have sufficient luminance
to avoid noticeable contrast between these
walls and the ceiling, a condition that causes
distracting contrast in VDT screens.

Downlighting Versus Uplighting
The appearance of a low-brightness direct
lighting system differs considerably from an
indirect lighting system. The direct system
produces negligible luminance on the ceiling
plane and provides great emphasis on the
horizontal work surface, furniture, and floor
coverings. The indirect system places lumi-
nance emphasis on the ceiling plane and de-
emphasizes the surfaces in the lower half of
the room. A direct-indirect system accom-
plishes both.

Lighting Art

Lighting Three-Dimensional Objects

Three-dimensional objects are perceived as

a result of the relationship between highlight

and shadow. Concentrated beams create

higher contrast and deeper shadows,

emphasizing form and texture. Frontal light-

ing, located 30° to 45° from the center of an

object in the horizontal plane and 30° to 45°

from nadir in the vertical plane, models

objects in a manner that replicates sunlight.

Lighting a vertical surface behind an

object provides a luminous backdrop to sep-

arate the object visually from its background

(figure 13.22), much the way an actor is

separated from the scenery on a stage.

Lighting an object from the side as well as

from above provides added dimension to the

piece.

Perception is disturbed when the

expected relationship of highlight and

shadow is reversed or when an object is

lighted from a less conventional angle.

Uplighting creates an ominous, ghoulish

impression (see figures 3.27 and 3.28).

Backlighting leaves an object in silhouette.

Paintings and Flat Works of Art

For lighting paintings and flat works of art,

two principal methods exist: uniform illumi-

nation and nonuniform illumination.

Providinguniformlighting for all vertical

surfaces that will receive art gives promi-

nence to the architecture; no hierarchy is

established among the individual works of

art, allowing viewers to select their own

focus. Objects can be changed without read-

justing the lighting equipment (figure 13.23).

Providing nonuniform lighting focuses

light on individual works while leaving the

surround in comparative darkness. This

gives prominence to the art over the archi-

tecture, creating a more dramatic environ-

ment. Every time the art changes, the

INTERIOR LIGHTING FOR DESIGNERS