The U.S. Department of Energy's CALiPER program has released Report 21.2, which is part of a series of investigations on linear LED lamps. Report 21.2 focuses on the performance of three linear (T8) lamps and a benchmark fluorescent lamp in five different troffer types. Also included are the results of a subjective evaluation. The LED lamps were intended as alternatives to T8 fluorescents and were chosen for the study primarily based on their luminous intensity distributions (narrow, medium and wide beam angles).
Based on both photometric testing and observer responses, LED lamps may work well in some troffers but poorly in others. Results show that linear (T8) lamps can improve luminaire efficacy in K12 lens and parabolic troffers, effect little change in volumetric and high-performance-type luminaires, but reduce efficiency in recessed indirect troffers. These changes can be accompanied by visual-appearance and visual-comfort consequences, especially when LED lamps with clear lenses and narrow distributions are installed.
Linear (T8) LED lamps with diffuse apertures exhibited wider beam angles, performed more similarly to fluorescent lamps and received better ratings from observers. Guidance is provided on which luminaires are the best candidates for retrofitting with linear (T8) LED lamps.
Originally published May 2014.