When the sensor readings were closely examined, it was found that some of the sensors measured much higher or lower illuminances
than the others, sometimes higher than the outdoor illuminance
The final knowledge base contains the main and interaction effects of each level of the ten design variables considered on illuminance
These values were collected and formed the table of recommended illuminances
in the first edition of the IES Lighting Handbook published in 1947.
They reported large variations in preferred desktop illuminances
, between 83 and 725 lx.
TM-24-13 concludes that both spectrum and illuminance
affect vision when the visual task is based on the ability to discern detail to ensure speed and/or accuracy.
Section 2 Methods describes the luminaire under consideration, then it shows that analytical calculations based on far-field intensities are inadequate to obtain correct illuminances
in the surgical site and finally it also explains how ray files were obtained by a near-field goniometer and used in simulation software to obtain illuminances
To get the overall daylight performance metrics from work plane point illuminances
, two methods are compared: (i) use the average daylight metrics of all points at each time step; (ii) at each time step, all points must meet the illuminance
requirement to get one credit for that time step.
Figure 8 shows mean ratings at the four different illuminances
in experiment 1 from Boyce and Cuttle; these ratings are averaged across the four levels of CCT.
The cart was then moved to the seating position of an occupant, where two illuminance
measurements were made: desktop illuminance
and cubic illuminance
at seated head position (not reported here).
For example, work plane illuminance
distribution is not an appropriate performance index since it changes with time.
were recorded in the mirror box in order to weight the measured luminances.
Her concern was with the inadequacy of current lighting standards based on roadway illuminance
for ensuring the visibility of targets for drivers and for making the sidewalks appear safe to pedestrians.