Determine the lamp wattage required to obtain an illumination level of 50 f-c over a 100 ft2 area if a fixture is used with a CU
of 0.75 and 80% of the available light reaches the work surface, the rest being absorbed by walls and other items in the space. Assume a luminous efficacy of 70 lumens/watt.
Lamp Wattage is utilized with a CU of 0.75 and 80 percent of the available light reaches the work surface, the remaining 20 percent is absorbed by walls and other objects in the space, resulting in an illumination level of 50 f-c over a 100 ft2 area
The term "lumen" refers to the emission of "luminous flux," which is a measurement of the total amount of visible light emitted by a source in a certain amount of time. The illumination level over a 100 ft2 area will be 50 f-c Lamp Wattage with a CU of 0.75 used, with 80 percent of the available light reaching the work surface and the remaining 20 percent being absorbed by walls and other objects in the room. Total Lamp Wattage = Number of Lamps X Wattage of Each Lamp. The fixtures' total wattage is 2 x 32, or 64 watts. Lumen per Fixtures equals Lumen Efficiency (Lumen per Watt) times the Watt of each Fixture 85x 64 = 5440 lumens per fixture.
