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.
Tables 1 and 2 show school and office illuminance recommendations, in footcandles
, as they developed in the 20th century.
That means that if the average footcandle
measurement for an area is 4 footcandles
, the level for any part of that area should never be less than one footcandle
Once the candlepower intensity of a fixture being considered for use is determined, some people use a mathematical formula to estimate the amount of footcandle
illumination at the target.
at a 24-inch height, and 13-foot spacings maintain 2.
By comparison, the new energy efficient Columbia replacement fixtures employ a single 32W T8 lamp powered by a Lutron Ecosystem electronic dimming ballast tuned to desired footcandle
and energy levels.
Site lighting for a small motel should be a minimum of one footcandle
, and the entire site should be uniformly lit.
The IES also offers specific footcandle
guidelines based on the lighting's purpose, whether it be safety or accent lighting.
levels underneath the ventilated fold are in the low 20s.
is the illumination on a one-square-foot surface by a uniformly distributed lumen of light.
New, organizationally specific guidelines informed by best practices could liberate us from faulty metrics like minimum footcandle
requirements and maximum lighting power densities.
From a daylighting perspective, this includes CRI levels, footcandle
levels and glare; human factors including circadian rhythms, flicker and productivity; client sustainability goals, tax incentives and regulatory drivers; and total cost of ownership that incorporates energy savings, maintenance costs and disposal fees.
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.
The built environment is created for people and therefore the light in a space should serve their needs and desires, not just be engineered to a predetermined footcandle
level," Berrigan said in an LD+A interview in 2013.
We replaced a 150 watt ceramic metal halide display on a one-to-one ratio with our LED and had more footcandles
on the display from our LED than the HID fixtures and at 40% energy savings.