The supplier went above and beyond to provide lighting schematics, foot-candle
specifications and a knowledgeable contractor to make the transition simple and easier to manage."
The research team calculated that the lighting level required for urban interstates is 0.37 foot-candle
(4 lux), which is significantly less than the 0.84 foot-candle
(9 lux) that IES recommends.
Control logic governs shade operation and artificial lighting levels, maintaining a uniform level of 20 foot-candle
ambient light for occupied laboratory spaces regardless of the time of day.
This includes the latest set of regulations issued by the International Code Council (ICC), which clearly details the need to light the treads and landings of interior stairways to “levels not less than 1 foot-candle
(11 lux)” and install lighting in “the immediate vicinity of the top landing of exterior stairs.”
Ample use of color also played a leading role in giving each department its own unique ambiance, as did the selection of the light fixtures, the foot-candle
contrast in each department, and the sleek use of graduated ceiling planes in several of the departments.
Measurements were made in foot-candles
, to a 10th of a foot-candle
The measurement they used in their research was the foot-candle
, or the amount of light put out by one candle, one foot away.
We recently conducted a research project in which the dining room provided only five foot-candles
of light at the table, which is well below the 50 foot-candle
At the meeting George Brainard (Thomas Jefferson University) demonstrated how our body stops producing melatonin --an important hormone that affects sleep, aging, and reproduction--when exposed to even a tenth of a foot-candle
of certain wavelengths of light.
The article "Relighting a Hangar"--one of the aeronautic theme stories in this issue--described how the Minnesota Air National Guard's maintenance hangar transitioned from a 5-10 foot-candle
mercury and incandescent system to a 1,000-W high-pressure sodium layout offering 100-plus fc using the same grid spacing.
For example, major roadways in North America typically are lit with an illuminance of no more than 1 lux, or 0.1 foot-candle
--roughly 10 times that from the full Moon.