Interior Lighting for Designers

Because the housing of a surface-mounted
luminaire is visible, it becomes a design ele-
ment in the space.
Pendant-mountedhousings also make
use of a recessed or surface-mounted junc-
tion box located at the ceiling for electrical
supply connection, but the luminaire is sep-
arated from the ceiling surface by a pendant
such as a stem, chain, or cord. The junction
box is concealed by acanopy(figure 12.5).
Pendant-mounted luminaires are used
to provide uplight on the ceiling plane or to
bring the light source closer to the task or
activity in the space. At other times pendant-
mounted luminaires are selected for decora-
tive impact, as with a chandelier.
In high-ceiling spaces, bringing the light
source down closer to the floor is often unnec-
essary. Instead of suspending the lighting ele-
ment down into the space, where it becomes
visually dominant, a more concentrated source
at the ceiling plane is less conspicuous.
With track-mounted luminaires, a
recessed, surface-mounted, or pendant-
mounted lighting track provides both physi-
cal support and electrical connection
through an adapter on the luminaire.
The main advantage of track is its flexi-
bility. Track is often used where surfaces and
objects to be lighted will be frequently or
occasionally changed, or added or deleted,
as in a museum or gallery. It also serves as
an inexpensive way to bring electrical power
to where it is needed in renovation and
remodeling projects.

Light and Glare Control

Luminaires can be divided into five categories
that describe their lighting function: down-
lights, wash lights, object lights, task lights,
and multidirectional lights.

Downlights
Downlights, also called direct luminaires,
produce a downward light distribution that is

usually symmetrical. They are used in multi-

ples to provide ambient light in a large space

or for providing focal glow on a horizontal

surface such as the floor or workplane

(figure 12.6).

Point source downlights

A nondirectional, concentrated light source

is often mounted in a reflector to control its

distribution and brightness because the

source would otherwise emit light in all direc-

tions. In an open-reflector downlight,a

reflector made from spun or hydroformed

aluminum accomplishes both purposes. A-

lamp downlights allow for efficient use of

inexpensive and readily available A-lamps

(figure 12.7).

Tungsten-halogen (figure 12.8), com-

pact fluorescent (figure 12.9), and HID

open-reflector downlights (figure 12.10)

operate under the same principle as the A-

lamp downlight. Fluorescent and HID aper-

tures are larger because the source is larger.

For a given source, the larger the aperture,

the greater is the efficiency of the luminaire.

Economy versions of the open-reflector

downlight, often called “high hats” or

“cans,” use an imprecise reflector to direct

light downward and either a black multi-

groove baffle or a white splay ring for bright-

ness control. These luminaires usually pro-

vide too much glare for visual comfort and

are inefficient at directing light down to hori-

zontal surfaces. Although they are less

expensive initially, they provide only short-

term value: more watts are used to achieve

an equivalent quantity of light.

Ellipsoidal downlights were early

attempts at controlling the luminance of the

source and providing a wide, soft distribu-

tion. They sometimes used silver-bowl lamps

and were excellent at reducing the bright-

ness of the aperture; they were, however,

inefficient at directing light downward. These

luminaires were large because the elliptical

INTERIOR LIGHTING FOR DESIGNERS