ingineria iluminatului - Journal of Lighting Engineering - Prof. Florin ...

5 Simulation study
An office building of 60 m 2 was chosen for
simulation, with four equal windows
covering the wall from the North part, each of
them having the dimensions of 2 m x 1.8 m
(height 1.8 m). The room surfaces have
reflection factors of 20/50/70. The task area
was established at 0.85 m. From the initial
measured light sources, four types are used
for simulations: luminaires equipped with
T8 36 W and T5 2x49 W fluorescent lamps and
electronic ballast, 62 W Greenlux and 37 W
Thorn LED luminaires. The illuminance
level at working plane was set at 500 lx.
The simulation aim was to compare
between different solutions that can be
employed in an office room, in terms of
luminous and power quality characteristics.
The light sources were also dimmed, to find
the dimming impact on the electric
characteristics for the different solutions.
The simulations were done using DIALux
and Matlab programs. In all four cases, the
luminaires were placed in parallel rows
with the windows. Different dimming levels
were set for each row.
For the first simulation, the luminaires
with T8 2x36 W fluorescent lamps were
used. The luminaires are positioned in three
rows parallel with the windows. Each row
has four luminaires. The row closest to the
windows was dimmed for 25% of the
luminous flux, the middle row for 75%, and
the furthest row, was not dimmed.
In the second simulation, luminaires
with T5 2x49 W fluorescent lamps were
used. The luminaires were positioned in
three rows parallel with the windows, each
row containing three luminaires. A similar
dimming scheme was applied.
Office lighting with old and new light sources
The third simulation was made with the
62 W LED luminaires - Figure 10. The
luminaires were positioned in three rows
parallel with the windows, each row having
five luminaires. The row closest to the
windows was dimmed to 33%, the center
row - to 63%, and the furthest row was not
dimmed.
In the fourth simulation, 37 W LED
luminaires were used. The luminaires are
positioned in four rows, each row
containing six luminaires. The row closest
to windows was dimmed to 20%, the two
rows in the center - to 60%, and the furthest
row was not dimmed.
Figure 10 Room under daylight and artificial light
for the third simulation (62 W LED luminaires)
Table 7 presents the measurement
characteristics of the light sources used in
simulation. The illuminance values from the
DIALux simulation study, at the work plane
level, for each of the four cases under study
are presented in Table 8. Table 9
summarizes the DIALux simulation total
illuminance, power and specific installed
power. The results are obtained without
dimming the light sources. Big differences
can be noticed in regard to the luminous
flux and active power, between different
cases.
Ingineria Iluminatului 2010; 12, 2: 5-22 17