Its own research, which analyzed the effect of IESNA-recommended light levels with regard to how secure they made people feel, showed that 1 to 3 footcandles
There are two qualifications of average footcandles
worthy of definition: a) Average initial footcandle
level of illumination on a roadway describes the illumination when lamps are new and luminaires are clean; and b) average maintained footcandle
level takes into account the depreciation of light output of the lamp throughout its normal life, dirt accumulation inside and outside of the luminaire, and other aging factors such as "frosting" or "sandblasting" of refractors and loss of reflector reflectivity.
for security, and you can achieve that a lot more easily with today's optics and not waste any light.
levels - when a system is first installed - may be as much as ten percent higher than maintained, but will drop off over time.
Basic to the process of measuring footcandles
is the availability and use of the proper measuring device.
If one were to simply follow current recommended footcandle
levels, either the needs of the client would not be met or lighting energy would be wasted.
01 average mean footcandle
level was achieved with an improved maximum/minimum ratio of 8:1.
Keeping the footcandle
ratio between task and general lighting no greater than 3:1 will appreciably lessen this effect.
By doing so, SEPTA increased the footcandle
level on the buildings and platforms five times over, which far exceeded IES guidelines.
Parking lot retrofits are generally one-for-one replacements with a target footcandle
range of 3-5 at the ground.
The starring role will be played by a light meter, which measures the footcandle
level on either a horizontal plane (the top of a desk) or a vertical one (the wall).
For more than half a century, the IES, through the efforts of the Recommendations on Quality and Quantity (RQQ) Committee and then its successor, the Quality of the Visual Environment (QVE) Committee, searched for a way to provide and identify a "good" footcandle
, one that minimizes direct glare and optimizes the occupant's visual performance rate.