Fig. 2 shows the lighting use patterns of the investigated offices.
As each office was divided into two lighting zones with an identical
floor area, lighting use patterns were classified as follows:
(1) All the lighting was off.
(2) Half of the lighting was on.
(3) All the lighting was on.
Lighting use patterns varied with the investigated offices. In the
office A, all the lighting was on during the 12 p.m. to 4 p.m. and the
proportion of time that half of the lighting was used accounted for
2% of the monitoring period. The proportion increased to 3% in the
office B. The proportion of the lighting was on in the office C ranged
from 55% at 9 a.m. to 79% at 6 p.m. The office D had a regular lighting
use pattern. The proportion of the lighting being on was 88% at
9 a.m., increased to 98% at 10 a.m., and remained almost constant
until 7 p.m. when the proportion reduced to 55%.
Table 4 describes the proportion of daily hours for each lighting
status of the investigated offices during the weekdays. The proportion
of hours that all the lighting was used was from 75% in the
office A to 42% in the office D (Person 2 = 2137.52, P < 0.001). A
period that half of the lighting was on in the investigated offices
was less than 3%.