Complex sentence: According to Lamp rerating formulae, reducing the voltage across an incandescent lamp by 10% reduces the power (and therefore energy) by about 16% and reduces the light output by about 31%.
Split into simpler sentences: According to Lamp rerating formulae, reducing the voltage across an incandescent lamp reduces the power (and therefore energy) by about 16%. Also according to Lamp rerating formulae, reducing the voltage across an incandescent lamp by 10% reduces the light output by about 31%.