1. Lux
The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area.[1] It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.

2. Lumen (unit)
The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. A lux is one lumen per square meter.
The lumen is defined in relation to the candela as
1 lm = 1 cd·sr.

3. Luminous intensity
luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.

4. Minimum colour rendering (Ra)
ILLUMINATION LEVELS IN INTERIORS
Educational
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Classrooms
300 19 80
TechnicaI drawing room
750 16
Computer practice rooms

5. Minimum colour rendering (Ra)
Healthcare - Wards
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
General lighting
100 19 80
Reading lighting
300
Simple examinations
Examination and treatment
1000

6. Hotels and Restaurants
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Kitchen
500 22 80
Restaurant, dining room, function room. -
Self service restaurant
200
Conference rooms 19

7. Minimum colour rendering (Ra)
Offices
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Filing, copying etc.
300 19 80
Writing, typing, reading, data processing
500
TechnicaI drawing
750 16
CAD work stations
Conference and meeting rooms
Reception desk 22
Archives
200 25

8. Minimum colour rendering (Ra)
Residential - Flats /Bedsits
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Lounge 19 80
Kitchens -
Bathrooms
150
Toilets
100

9. Minimum colour rendering (Ra)
Retail Premises
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Sales area
300 22 80
Till area
500 19
Wrapper table

10. Minimum colour rendering (Ra)
Theatres, Concert Halls and Cinemas
Area
Illuminance (lux)
Limiting Glare rating
Minimum colour rendering (Ra)
Practice rooms, dressing rooms
300 22 80
Foyers
200 -
Auditoria
100

11. Industrial Environment
Area
Illuminance (lux)
Lifts
100
Corridors and stairs
Toilets
Canteens
300
Mess rooms
Plant rooms
Store rooms

12. The simplest schemes for lighting are:-
1- Direct lighting
2- Semi direct lighting
3- Semi-indirect lighting
4-Indirect lighting
5- General lighting

13. 1- Direct Lighting:-
widely used lighting system,in this system more than 90% of the total light fulx is made to fall directly on the working plane with the help of deep reflectors.
its is mainly used in general outdoor and industrial lighting.

14. 2-semi dierct lighting:-  
In This lighting scheme 60 to 90% of the total light flux is made to fall downward directly with the help of semi direct reflectors.
reaming light is used to illuminate the ceiling and walls. such a lighting scheme is best suited to room with high ceiling where a high level of uniformly distributed illumination is desirable.
the Glare in such units is avoiding by employing diffusing globe which not only improve the brightness toward the eye level but also improve the efficiency of the system with reference to working plane.

15. 3-Semi-indirect lighting:-
In this lighting scheme 60 to 90% of total flux is thrown upwards to the ceiling for diffuse reflection and the rest reaches the working plane .
direct excepts for some absorption by the bowl .This lighting scheme is with soft shadows
and glare free.
it is mainly used for indoor light decoration purpose.

16. 4-Indirect lighting:-
In this lighting scheme more than 90% of total light flux is thrown upwards to the ceiling for diffusion reflection by using inverted or bowl reflectors.
in such a system the ceiling acts as the light source, and the glare is reduced minimum.

17. 5-General lighting:-
In this scheme lamps made of diffusing glass are used which give nearly equal illumination in all directions