* The replacement of lighting equipment by more efficient devices providing the same 500 lux (46.5 footcandle
) illumination with a reduced electric power (from 10.6 W/[m.sup.2] to 6 W/[m.sup.2] [from 3.36 Btu/h.[ft.sup.2] to 1.90 Btu/h.[ft.sup.2]]), provides 18% final electricity consumption energy savings.
Maintaining good color recognition from high-pressure sodium lamps, Bullough says, can be achieved by using at least 3 footcandles
Since the American Standard Recommendation prescribes illumination in terms of footcandles
on the horizontal plane and emphasizes reduced glare, there has been a tendency to use luminaires with sharp cutoffs of the main beam, which directs the light predominantly down onto the pavement surface.
For championship play, 35 footcandles
or over maintained evenly distributed - within 10 percent - and measured with a light meter about 42 in.
. Basic to the process of measuring footcandles
is the availability and use of the proper measuring device.
A parking lot generally requires O.S footcandles
for security, and you can achieve that a lot more easily with today's optics and not waste any light.
You don't need the same type of lamps in every area--for example, in Research & Development, we need 72 footcandles
at the desktop because they do fine work, but we don't need 72 footcandles
at the floor level in the warehouse.
The formerly washed-out parking area is now cheerfully lit, with an average light level of 3.1 footcandles
(a 109% increase) and uniformity at an average/minimum ratio of 4.4:1.
Consult the Illuminating Engineering Society's footcandle
recommendations for different tasks and age groups to see if you're overlighting any areas.
Although the light offers excellent efficiency when it comes to overall footcandle
output, it is weak in the area of distribution and overall uniformity.
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.