Training - Lighting Fundamentals

April 18, 2023 Training Module - Lighting Fundamentals

MEASI ACADEMY of ARCHITECTURE

TRAINING ON LIGHTING FUNDAMENTALS

PRESENTER AANUPAM RAO



Light is Life


What is Light ?

• Light is a Part of Radiant Energy which excites Human Retina and gives Visual Sensation.

• Light is a part of Electromagnetic radiation


Electromagnetic Spectrum


Theories of Light propagation

• Particle Theory : Units of Energy are propagated at the speed of light in straight line from light source in form of particles

• Wave Theory : Energy is propagated at speed of light in wave fashion same as that of sound.


Visible Spectrum

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Rainbow


Visible Spectrum

• Visible spectrum varies from Violet (380 nm) to Red ( 760 nm)

• On lower side of spectrum ultra violet is emitted, part of which can be converted into visible spectrum

• On higher side of spectrum Infrared is emitted which is used for medical therapy

LIGHT AND VISION




Photopic Vision Mesopic Vision Scotopic Vision


Eye and Vision


Relative Spectral Sensitivity of Eye

• Sensitivity of Eye Changes during day time and night time.

• Day time Vision – Eye more sensitive to Yellow ( 555 nm)

• Night Time Vision – Eye more sensitive to Blue ( 480 nm)

LIGHT DIRECTION PROPERTIES


Light Direction Properties

• Reflection

• Refraction


Light Direction Properties

• Transmission






Photometry

• It is the process of measurement of light, its properties and qualities.

• The basic instrument employed is called Photometer


Solid Angle

• The concept of light and various parameters is associated with concept of solid angle ().

• It is ratio of spherical area (A) to sqaure of radius ( R )

= As/R2


Luminous Flux

• Rate at which light is emitted by lamp.

• It is measured in Lumens (Lm)

• Its symbol is

April 18, 2023 Training Module - Lighting FundamentalsNext Slide


Luminous Intensity

• Amount of light emitted by light source in a particular direction

• It is measured in Candelas (Cd)

• Its symbol is I



Illuminance

• It is Luminous Flux on working plane per square meter of area.

• It is measured in Lux

• Its symbol is E• E = / A



Luminance

• It is brightness of luminous surface as perceived by human eye.

• It is measured in Cd/Sqr. M.

• Its symbol is L



Luminous Efficacy

• It is ratio of total luminous flux emitted by lamp to total power consumed by lamp.

• It is measured in Lm/W.

• Its symbol is


Light Output Ratio

• It is ratio of total luminous flux emitted by Luminaire to total luminous flux of bare lamp.

• It is indicated in % age.

• It is measured in controlled operating conditions.


Light Output Ratio

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Glare

Direct Glare Indirect Glare


Reflectance

• It is percentage of luminous flux reflected by a surface.

• Its Symbol is .

• Dark surfaces have lower reflectance while bright surfaces have higher reflectance.


Uniformity

• It is expressed as ratio of minimum to average illuminance(Uniformity = Emin/Eavg)

• In some applications it is also measured as ratio of minimum to maximum illuminance (Uniformity = Emin/Emax)



Maintenance Factor

• It is a safety factor used in application design for depreciation in terms for – Lumen Output of lamp– Deterioration of reflecting surfaces– Deterioration of reflecting properties of

surrounding surfaces– Lamp Burn Out


Black Body Radiation

• Concept of Colour is related to concept of Black Body.

• It is a idealised enclosure which absorbs all the light incident on it and has zero reflective radiance.


Colour Temperature

• The light colour of light source is defined in terms of Colour Temperature (Tc).

• Its unit is Kelvin ( K)• Kelvin Temperature scale begins at

absolute zero ( O °K = - 273 °C) • The colour temperature of light source is

used to denote the colour of light source by comparison with colour of standardised black body radiator



Colour Temperature



Colour Rendering Index (CRI)

• It is an index indicating how closely the colour of an object matches its appearance under relevant reference light source

• It is indicated on a scale from 0 to 100


• Higher CRI reproduces surface colours accurately

• Higher CRI gives natural skin colours



• Effect of Light source with CRI = 100

• Effect of Light Source with CRI = 23



Lighting Laws

• Inverse Square Law

• Cosine Law


Inverse Square Law

• Illumination (E) at a point on surface varies directly with luminous intensity (I) of light source and inversely with square of distance (d) between light source and surface

• E = I / d2



Cosine Law

• Illumination (E) at a point on a surface varies as cosine of angle of incidence ()

• Hence E = I * Cos / d2


RECOMMENDED ILLUMINATION

• FOR OFFICE AREAS: 300 LUX

WORKSTATION – > 350-400 LUX.

CONFERENCE ROOM -> 500 – 600 LUX.

• FOR INDUSTRY : 300 LUX.

PRODUCTION AREAS: 300-350 LUX.

WAREHOUSE: 200 LUX.

• STREET & EXTERIOR LIGHTING: UPTO 30 LUX.


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