Are T5 lamps good for the environment?
Although the efficacy of T5 lamps is equivalent to that of T8 lamps, the compact size of T5 lamps reduces the amount of materials used in their manufacture, the potential for toxic substance contamination, and packaging materials needed for shipment and sale. T5 lamps can, therefore, have less impact on the global environment than T8 lamps.
In addition to their smaller dimensions, T5 lamps have an improved phosphor coating that prevents mercury from being absorbed into the phosphor and the bulb glass. This technology allows for reduced mercury content in the lamp, as well as higher lumen maintenance. A T5 lamp includes less than 3 milligrams (0.0001 ounces) (Van Vleef 1996) or 5 milligrams (0.0002 ounces) (GE Lighting, T5: Online Video, 2002) of mercury.
Compared to the larger T8 or T12 lamps, T5 lamps save material. The reduced surface area allows manufacturers to use nearly 60% less glass and phosphor material when manufacturing T5 lamps as compared to T12 lamps (Yancey 1998). Manufacturers claim that a T5 lamp requires 38% less glass than a T8 lamp (GE Lighting, New Linear Fluorescent Lamps, 2002). In addition, moving from T12 to T5 lamps can reduce packaging materials by up to 50% (Yancey 1998).