A “lumen” is an industry standard measurement of light output. It is measured by an electronic meter from a single direction of the light source. The resulting measurement of “bare” light bulbs is usually printed on the box by the bulb manufacturer. While this information is useful, there are other factors to consider.
1. Color - The electronic meter does not record the same wavelengths as seen by the human eye. So, while the electronic meter may record both Cool White and Warm White bulbs as having the same “lumens”, the human eye will actually register the Cool White as being “brighter”.
2. Fixture - The standard lumen chart is the rating of the bare bulb. It does not take into consideration the type of fixture that holds the bulb. Most fixtures will actually reduce that lumen level by 10-40% or even more depending on design. Items such as decorative metal work or a frosted lens can greatly reduce the light output.
3. Direction - The meter records only a single point from the bulb, however, we are interested in “all” the light emitted to cover an area. The fixture design must also be considered. A well designed fixture will have reflectors to redirect light that would have been lost into useable light. In cases of a “flood” or “spot” style fixtures, the lumen output can be increased above the rated level of the meter by changing the direction of the output.
If you are having an issue with areas of your property (inside or out) that are too dark or too bright or want to add ambiance lighting for aesthetics or decoration, do not rely on a lumen chart, speak to the experts at Divine Lighting. Whatever your lighting issure, we have a solution!