That said, the amount of energy used for
manufacturing processes, shipment and
recycling is comparatively small. The operation
of lighting installations accounts for
more than 90 percent. So, electricity consumption
is by far the most important factor
in the energy balance – and the most important
cost factor as well. It also determines
how much climate-damaging carbon
dioxide is emitted when a luminaire is in
operation. Lighting industry and science are
thus working hard to increase lighting’s
energy efficiency even more. The progress
that has been made can be clearly seen
from a comparison of conventional incandescent
lamps with modern LED lamps
(see fig. 17): while incandescent lamps
have a primary energy input requirement of
nearly 3,300 kilowatt-hours (kWh) per
25,000 operating hours, LED lamps consume
only around 660 kWh.