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 with emissions 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, the usage of an incandescent lamp may be responsible for mercury emissions. 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.

The main purpose of this life cycle analysis is to compare the incandescent lamp with more efficient light sources. In fact, the LCA of this lamp can be seen as a representation of all incandescent lamps. Due to the very similar material composition of these lamps, the Cumulated Energy Demand of the production is approximately the same for all types. For the use phase, 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.