Wireless Sensor and Actuator Networks for Lighting Energy ...

Seven-occupant case with simulated daylight fluctuation sequence
Given the promising results of the lighting system responding to the wellplanned
daylight changing sequences in the previous two cases, a more close-to-real
daylight fluctuation sequence was employed to evaluate the system performance. The
same seven occupants and lighting preferences as the preceding case (Figure 9-20) were
considered in this test. The daylight fluctuation data was measured using a photosensor
placed five feet away from a north-facing window on an ordinary day with a sensing
rate of ten seconds per sample as shown by the blue line in Figure 9-25. In order to
make it possible to replicate the sequence of daylight change with the daylight
simulating structure, the daylight fluctuation data was sampled every ten minutes and
scaled to fit the operation range of the simulating structure. The red crosses in Figure
9-25 indicate the data points considered in this test, and the light output from the
daylight simulating structure was adjusted accordingly every minute instead of every
ten minutes. As a result, the simulated daylight followed the trajectory in Figure 9-26.
Figure 9-25 Measured daylight fluctuation.
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