After few experimentations, I found a part of the answer.

There are my suggestions to get precises data from sensor (Column of daylight Sensor Illuminance) in the .ill file.

1) The orientation of the sensor in the model is very important. Be sure that the sensor is oriented to the window:

2) When you add Radiance Daylighting Measure in OpenStudio, be sur to put the Radiance settings at High:

• 1) Add the Radiance Daylighting Measure to your model;
• 2) Then, clic on the measure, in the right column set the Radiance settings at high.

I hope it could be helpful,