Posted By: tonyWhat does he think happens to the other 2% ??? -- it is all converted to heat.

The highest efficacy theoretically attainable (i.e., 100%) is 685 lumens per watt, the same which could be obtained if all the input power were converted to green light at a 555 nm wavelength, the number to which the human eye is most sensitive.

The maximum theoretical efficacy of any white, light-producing source, one with its entire output power distributed uniformly (with respect to wavelength) in the visible region, is only 200 lumens per watt. Thus, by concentrating any light source’s output wavelength in close proximity to the 555 nm point, we can improve the efficacy beyond that possible with “perfect” white light, that comprising all visible wavelengths, with an equal amount of power in each wavelength.

The efficacy of average present-day fluorescent lamps is about 60 to 70 lm/W, although some high-end ones rate higher. Comparatively, a typical incandescent light with15 lm/W efficacy is about 2% efficient -- 98% of its electrical power input becomes heat. An LED or CFL lamp, with 100lm/W, is about 14% efficient and 86% of its electrical power input converts to heat.

Typically 98% of an incandescent lamp’s electrical power input converts into radiant heat and therefore designers discount heat removal; an LED emitting at 555 nm with 70lm/W, converts almost 90% into conductive heat, which must be removed for optimal lamp performance.

If lighting engineers create a white light source where the electrical power input is uniformly distributed over all visible spectrum wavelengths, they would achieve the maximum theoretical efficacy of 200lm/W. The result is a white light source with perfect color rendering index (CRI).

Posted By: cloudy_thoughtsJust curious, but does anyone know what the figures would be for gaslight?

Posted By: fostertomAs CFLs work by exciting various metallic gasses incl. mercury to bathe us in their characteristic complex wave pattern, that's equivalent to taking e.g. mercury, certainly as a homeopathic remedy of uncontrolled potency, which may or not beneficiial or harmful; maybe also or alternatively mercury as the gross poison that it is.

Posted By: fostertomIn homeopathy, a fundamental principle, amply proved empirically, is that 'potency' increases exponentially with successive dilution of the remedy, during preparation. Successive order-of-magnitude dilutions quickly result in a little soluble pill which in probability contains not a single molecule of the original active ingredient - and the higher that probability, the greater the potency of the preparation, in line with the well-proved medical effect of the original ingredient

Posted By: fostertomThe fact that homeopathic medicine has worked for the last 300yrs,

Posted By: marktime which in probability contains not a single molecule of the original active ingredient - and the higher that probability, the greater the potency

Posted By: RobinBLightbulbs ! Would it make sense if all lightbulbs were labelled with lumens rather than watts?