Simulation on the 21 of september

Xavier, The reason simulations are typically run on the equinox is because the sun is at the equator, its neither at its highest or lowest altitude in the sky. You can run on March 21st or September 21st. Daylight Factor calculation is different type of calculation than illuminance calculation. DF is calculation uses the CIE overcast sky value. DF is the percentage of the exterior horizontal illuminance value that reaches a point inside a space. Having a DF of 2% is good. Illuminance calculations is the value, either in lux or footcandles, on a point in building under all type of sky conditions. What you want to do in AGI-32 is calculate the illuminance value. There are alot of good books on daylighting, "Daylighting in Sustainable Building, Daylight in Buildings, "Sun, Wind, and Light". There are also a lot of good sources on the web that talk about daylighting strategies, the different types of metrics, calculations, etc. The Daylighting Collaborative, and the Whole Building Design Guide, are just few of the many sources that i suggest you may want to read to get a better understanding of daylight and daylight simulations.

Are you asking what the typical illuminance is for a CIE overcast sky or just an overcast sky condition in general? Off the top of my head i believe CIE overcast is 1000 lux. In the program, put a ground plane in, place a sensor at 30" facing up, run the simulation under the specific sky condition at noon, this will tell you what the computer program is using.

Xavier, First off, this is a v3 forum, so calculating the daylight factor is not an option for v3 projects. If yo have a v2.2 or even a schools 2007 project, then you have the option to use the glazing factor calculation method. If you are going to be using the simulation method in v3, then you should be focusing on illumance calculation in AGI-32. Ok, so you ran a sim with 333 fc, which to me is pretty low, for a CIE overcast sky. Not sure of of all your inputs etc, but that is low. 2% of 333 is rounded up to 7 fc which is well below any level for a regularly occupied space. Is the sensor facing up? I would suggest that you look into AGI-32's help forum. I believe they have some video tutorials that can help you set your model for simulations. Make sure you have the task of setting up your model and getting all your input parameters correct. The biggest problem with simulations is incorrect input. This will always give you false reads. If you follow the false reads, you will actually make the incorrect design decisions. Part of knowing simulation is knowing when the outputs are false. Good Luck.