For a bulb with such a small diameter, T5 bulbs are bright and efficient light sources. The electronic ballasts used in high output T5 lighting applications can produce well over 100,000 starting voltages before they begin to lose efficiency. These bulbs are also known to last well over 20,000 hours.
All man-made light sources experience some level of lumen depreciation over their rated lives. The measurement, "lumens," dictates the intensity of a light source's light output. Lumen depreciation refers to a light source's ability to retain high lumen output levels throughout the source's rated life. T5 fluorescent bulbs will only depreciate between 8 and 10 percent of their rated lumen output throughout their lives.
While one single T5 light bulb does not have the capacity to match the intensity and light output of one high intensity discharge bulb, four T5 bulbs combined offer a comparable output. T5 fluorescent bulbs are often found in desk lighting applications, while high output T5 bulbs are typically used as light sources for whole rooms or warehouses.