The combination of these properties yields a mantle that, when heated by a kerosene or liquified petroleum gas flame, emits intense radiation that is mostly visible light, with relatively little energy in the unwanted infrared, increasing the luminous efficiency.
12.
Within the visible spectrum, wavelengths of light are weighted according to a function called the " photopic spectral luminous efficiency . " According to this function, 700 nm red light is only about 0.4 % as efficient as 555 nm green light.
13.
In practice, most buildings that use a lot of lighting use fluorescent lighting, which has 22 % luminous efficiency compared with 5 % for filaments, so changing to LED lighting would still give a 34 % reduction in electrical power use and carbon emissions.
14.
The luminous " efficiency " is defined as the ratio of the luminous efficacy to the theoretical maximum luminous efficacy of 683 lpw, and, as for luminous efficacy, is of two types, radiant luminous efficiency ( LFR ) and source luminous efficacy ( LFS ).
15.
This means that white ( or whitish ) light sources produce far fewer lumens per watt than the theoretical maximum of 683.002 lm / W . The ratio between the actual number of lumens per watt and the theoretical maximum is expressed as a percentage known as the luminous efficiency.
16.
Lattice constants of the compounds also tend to be different, and the lattice mismatch against the substrate, dependent on the mixing ratio, causes defects in amounts dependent on the mismatch magnitude; this influences the ratio of achievable radiative / nonradiative recombinations and determines the luminous efficiency of the device.
