Convert lux to nox

Lux is lumens per square metre, the light falling on a surface. Direct sunlight is 50,000–100,000 lx, an overcast day around 1,000, an office desk should have 500 (the European workplace standard EN 12464-1), a living room in the evening 50–150, a street at night 5–20, and full moonlight about 0.2 lx. The foot-candle of US lighting practice is one lumen per square foot, 10.76 lx; the phot and the nox are obsolete.