They provide efficient use of light on work
surfaces while relieving contrast by reflecting
light from the ceiling plane (figure 3.14).
Multidirectional distribution created with
concentrated beam-spreads is calledmultidi-
rectional concentrated(figure 3.15). It is also
calledsemidirectif 60% to 90% of thelumens
(light emanating from the luminaire) are
directed downward, andsemi-indirectif 60%
to 90% of the lumens are directed upward.
A higher contrast, nonuniform bright-
ness condition is produced with concen-
trated distributions present in both the
upward and downward components. The
upward component reduces excessive con-
trast in a space; however, the nonuniform
light reflected from wall or ceiling surfaces is
insufficient to “wash out” all shadow and
contrast. This lack of diffusion yields moder-
ate contrast (figure 3.16).Figure 3.13 Direct/indirect
distribution. Figure 3.14An example of direct/indirect distribution.
Figure 3.15Multidirectional con-
centrated (semidirect or semi-indi-
rect) distribution. Figure 3.16An example of multidirectional concentrated distribution.