Convective venting in compact fluorescent fixtures

Convective venting studies done on three different compact fluorescent fixtures indicate that the reduction in light output and efficacy caused by a highly constricted thermal environment can be nearly eliminated with a proper venting configuration. Experiments conducted on an open, recessed ceiling fixture housing two 26 W, quad-tube, compact fluorescent bulbs indicate a light output loss of 15% for an unvented fixture; with an aperture area of approximately 1.5 square inches (a 0.5 in*3.25 in vent) placed in the top of the fixture, thermally-induced light output losses are reduced to about 3%, while optical losses due the aperture´s size are only about 4%. In an enclosed recessed fixture, housing two 13 W, twin-tube bulbs, light output and efficacy losses are noted at 18%; both of these decrease to only 2% losses with two small, lower vents and a larger, upper vent introduced to the fixture. In a smaller, enclosed, recessed downlight, housing two 7 W bulbs, losses for both the light output and efficacy of the fixture are originally noted at 10%; with three vents introduced to the fixture (in the same configuration as the other enclosed fixture), light output reached at 98% of maximum, and lamp efficiency reached 96% of maximum.<>