Laws of illumination.

 

The lumen method is a way of calculating how many lamps will be needed in a given area or room to achieve the required average illiminance

 

 

N = number of lamps

E = illuminance required (in lux)

F = luminous flux (lumens) for 1 lamp

 

Mf = maintenance factor - this depends on how  quickly the lamps will get dirty or dusty and how often they will be cleaned. this is usually about 0.8

UF = utilisation factor - this depends on the colour and reflectiveness of the walls, ceiling and other surfaces, this is usually about 0.6.

 

Efficacy 

colour rendering

quantities - Luminous flux - lumens

luminous intensity - candelas

illuminance - lux

 

Minimum lux levals 

Laws:

Inverse square law

cosine law

lumen method.