In Europe, the illumination from the point of view of work is defined according to the Daylight Factor, DF, which can be calculated according to two methods, the one established in a experimental way by data of n-site date under covered cloconditions and the other one defines defa theoretical way under clear sky conditions. But in every each the requirements fixed from for thctor are established for the mainland France metropolitoto be ahe climate of the islaon. Indeed, the FLJ DF deteed by the International Committee of Lighting, sets under the conditiskyconditio the available illumination inside the room and outside. The factor of comparison obtained is called Daylight Factor and expresses itself in percentage.

The following table [5] gives the percentage of time where three values of outdoor illumination are met during a typical year. In France, the value of 5000 lux is preferred in the calculations. The DF value of reference applied in France is 2.5 % [3] under cloudy sky conditions. This rule is not

adapted to tropical conditions with a mean illuminance much pore important compared to mainland France. DF values of 1.5 % are recommended by Adelard [2] so far.

It turns out that the criterion of the only daylight factor is not sufficient to characterize the performances in daylighting. The percentage of autonomy in natural lighting proposed by Reinhardt seems more adapted. These choices fit with the objectives of the task 31 of the International Energy Agency concerning the establishment of performances and strategies in the daylighting design in buildings [6].

2. Methodology