Energy saving Light Bulbs

Energy saving light bulbs use only 20% of the energy used by the regular incandescent bulbs , a 20 watt energy saving bulbs has about the same light output  as 100 watt incandescent bulb .
The energy saving bulbs’  life-span is 6 times longer than the standard incandescent lights as the life time of the standard incandescent is 1000kwh (6 months operation ) while the life time of the energy saving lights is 6000 kwh( 3 years operation) .
The table below indicates the total cost of the standard incandescent lights and the energy saving lights   , it also shows that the energy saving lights is more longer than the standard incandescent lights :