Daylight Simulation Methodology

If I understand it correctly then it goes like this:

1 LEED for Schools v3.0 Indoor Environmental Quality Credit 8.1 (IEQc8.1) Daylight and Views - Daylight
Daylighting Simulation Requirements according to LEED for Building Design & Construction BD&C v3.0 Reference Guide

Steps
1. Identification of all "regularly occupied" rooms and their respective areas in ft².
2. Identification of all "regularly occupied" day lit rooms and their respective areas in ft².
3. The daylighting simulation applies only to "regularly occupied" day lit rooms.
4. Identification of all Windows, Surfaces and their respective material properties in English with standard American units, e.g. Glass Area in ft², VLT visual light transmittance or Tvis, SHGC solar heat gain coefficient.
5. Tabulation of all Windows, Surfaces and their respective "glare control" (such as motorized blinds).
6. The Simulation takes into account the emission and reflection properties of internal surfaces such as walls, ceilings and floors.
7. Output results are based on a height of 30" from finished floor level (FFL) and data points are distributed on a 5 ft x 5 ft grid.
8. The Simulation is made assuming "clear-sky" conditions.
9. The Simulation includes for the planned building’s location in Latitude and Longitude.
10. The Simulation includes for the planned building’s orientation relative to north.
11. The simulation is run once at "09:00" in the morning and once at "15:00" in the afternoon on the Equinox (21 March or 21 September).
12. Light intensity is given in "foot candles" ftcd. 13. Tabulate the natural light intensities (in "foot candles") for
both simulation runs seperately.
15. Sum all the 5x5 ft areas that meet the criteria of having a light
intensity between 25 and 500 ftcd, for both simulation runs and devide
by double the simulated area to find the average area that conforms.
16. Divide this by the total "regularly occupied" area to find the
percentage acceptable day lit area.

Definition: "regularly occupied" rooms: "areas where people sit or stand as they work."

Omer, the credit language is a little unclear on the two times of simulation. We interpret it as that 75% of the space should receive 25 foot-candles of daylight both times of the day, at 9 AM and at 3 PM. You count the space only if it meets the 25fc at both times.

To support what Shillpa is saying, I received this statement in a response from USGBC Technical Customer Service:

"The simulation needs to document compliance at both 9:00 a.m. and 3:00 p.m.. Only areas that meet the requirements at both of these times are considered complaint."

To me, this means that you cannot take an average and you cannot evaluate the two times separately, ie. you cannot include the space in the compliant area if 75% of it meets the footcandle requirement at 9am and then also meets it at 75% at 3pm (unless that 75% overlaps.)

Please let us know if you have experienced receiving of this credit otherwise.

Is it 75% and 90% of each individual space or of the total of all spaces?

Total of all spaces.

Update: I spoke with a colleague today who told me that she has had luck with reviewers when using the "averaging" method. The method is: calc at 9 and 3. If each of those times meet the 75% individually, take the average of those square footages and use that to enter into the reporting spreadsheet. So, once again...it all depends on what reviewer you get apparently.