Energy saving bulb energy rating a power 7 watt energy consumption 7 kwh1000h series osram superstar micro twist equivalent to light bulb 39 w socket e14 voltage 230 v light colour warm white light output 420 lumen colour temperature 2 500 k lifespan 12 000 h bulb shape spiral tube style bulb housing length 90 mm average annual electricity cost 01951 kwh 137 euros source average electricity cost based on figures from eurostat as of 2016