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.

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.

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.

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

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

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

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

Minimum colour rendering (Ra) Residential - Flats /Bedsits Area Illuminance (lux) Limiting Glare rating Minimum colour rendering (Ra) Lounge 100 - 300 19 80 Kitchens 150 - 300 - Bathrooms 150 Toilets 100

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

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

Industrial Environment Area Illuminance (lux) Lifts 100 Corridors and stairs Toilets Canteens 300 Mess rooms 150 - 300 Plant rooms Store rooms

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

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.

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.

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.

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.

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