Fluorescent lamps come in a variety of sizes and shapes but tube diameter is the important consideration when it comes to energy efficiency. The lamps are designated by type and their diameters in eights of an inch. (Ex. T12 means Tube-type 12/8 inch diameter). The T12 is the oldest, most common version and most inefficient yet it still enjoys widespread use due to cheap lamps and parts.

The T8 was designed specifically to be compatible with the T12, making retrofits simple. In a given light fixture, four T8 lamps will produce more light than four T12 lamps while consuming the same amount of energy. This makes it possible “de-lamp” legacy T12 fixtures and replace four T12 lamps with only two T8 lamps, resulting in energy savings of at least 50% while keeping an equal level of illumination. Since fewer bulbs are required, maintenance and bulb replacement costs are reduced.

Applications :

  • Anyplace still using T12 linear fluorescent lamps.

Advantages :

  • Low initial cost
  • Same level of illumination for less wattage.

T5 :

The T5 was designed for more high output purposes, replacing the high bay lights commonly seen in industrial complexes. Technically, they do not provide more light output than a T8. However, individual lamps may appear brighter since there is less surface area available to emit light. For this reason T5s are more commonly used in place of high bay fixtures where glare is less of a concern. A fixture with four T5s can replace legacy high bay lighting while providing a 40% reduction in energy consumption. Moreover, these T5s will retain their lumen output far longer than legacy lighting systems.