A light-emitting diode (LED) is a semiconductor diode that emits narrow-spectrum light. Depending on the used material, LED are able to emit light in different colors. To produce white light, the light of blue LED is passed through yellow phosphors, whose composition determines the final color temperature. To make LED usable in household fixtures, several LED are combined with an electronic control gear in a bulb-shaped form. By selecting appropriate white LED, it is possible to offer LED systems with the same light colors as fluorescent lamps. Due to their remarkably low energy consumption, their extremely long life and their low maintenance cost, LED lamps are the most efficient household lamps.

The following table depicts the environmental impact of the LED lamp during production, including the Cumulated Energy Demand (CED) of this life cycle stage.

The Cumulated (primary) Energy Demand during the use phase is calculated from the wattage of the lamp, its average lifetime and the energy mix.

The graphs below outline the Cumulated Energy Demand and the Global Warming Potential of the use phase in comparison to the manufacturing phase. For the calculation of the CO2 emissions resulting from the use phase, an electricity mix of 0.55 kg CO2 per kWhEl was taken as a basis. Of course electricity production during use is also responsible for other environmental impact categories, but this depends very much on where the lamp is used. For this reason we have only depicted the CO2 impact, which may also vary depending on the location of use.
Equally depending on the electricity mix, an LED lamp may also be responsible for mercury emissions during use. This is due to the comparatively high ratio of coal power plants in some electricity mixes, which emit mercury by burning lignite or hard coal to produce electricity. Nevertheless, in comparison to incandescent and halogen lamps, LED lamps are associated with far less mercury emissions during use. This is due to their high energy efficiency which is responsible for saving up to 80 percent of electricity and thus for reducing mercury emissions resulting from electricity production by coal power plants. LED lamps offer the lowest possible mercury impact on the environment.

Similar to compact fluorescent lamps, different types of LED lamps have different impacts during production. Due tot he dynamic development of LED lamps, a generalization of the relationship between light output and impact ofproduction is very difficult. However, the use phase continues to be the most influential life cycle stage with the greatest impact, so it is much more important to calculate the effect of this phase. For this purpose, it is merely necessary to recalculate the Cumulated Energy Demand based on the wattage of the lamps, according to the three steps illustrated in the table above.