L1 Illumination and daylight factor

Task (as outlined in main handout on Environmental Measurement)

Select a suitable lecture room (LR5 or LR6) where you can take readings undisturbed. First measure the daylight factor at desk-top level on two lines across the room, one at a main window, one between windows. (The daylight factor is the ratio of illuminance on a horizontal plane at a point in the room to the unobstructed diffuse sky illuminance outside – simultaneous readings in overcast weather are desirable.) Compare with methods of calculating daylight factors, and comment.

Next, survey the actual desk-top illuminance across the room, at different times of day, with artificial lighting, etc., and note subjective responses. Compare with standard recommendations for such rooms.