This document discusses the importance of architectural lighting. It explains that lighting helps create an emotional experience for occupants and draws attention to textures, colors, and forms. There are three key aspects of architectural lighting - aesthetic, function, and efficiency. Aesthetic focuses on the emotional impact of lighting. Function ensures lighting allows for safe navigation. Efficiency creates breathtaking lighting designs that are also energy efficient. The document also covers day lighting properties, interactions of light with surfaces, photometric quantities like illuminance and luminance, and factors of illumination quality.

1. Kantipur International College
Department of Architecture
Architectural lighting
Ar. SamikshaAdhikari

2. Importance of Architectural lighting

3. Importance of Architectural Lighting
•Lighting can bring an emotional value to architecture—
it helps create an experience for those who occupy the
space.
Without lighting, where would architecture be? Would it
still have the same impact?
 No, it wouldn’t. Whether it’s day lighting or artificial
lighting, light draws attention to textures, colors, and
forms of a space, helping architecture achieve its true
purpose.

4. Importance of Architectural Lighting

5. Importance of Architectural Lighting
To create a successful balance between lighting
and architecture, it’s important to remember three
key aspects of architectural lighting:
1. Aesthetic
2. Function
3. Efficiency

6. Importance of Architectural Lighting
Aesthetic
•It is where designers and architects focus on the
emotional impact the balance of lighting and
architecture will have on occupants
•It’s where designers determine how they want people to
feel when they walk around a space
•This aspect is especially important for locate locations;
exterior lighting should draw the consumer in, and the
interior lighting should awe them as they walk through
the doors in addition to showing off product

7. Importance of Architectural Lighting
Function
•This aspect cannot be overlooked. We want the lighting to
look a certain way, but we have to also make sure it serves
its most important purpose—to help us see
•Areas should be illuminated so occupants feel safe when
navigating a room or entire building
•They should be able to see the floor and walls around
them, which should create a feeling

8. Importance of Architectural Lighting
Efficiency
•This aspect is very important in today’s age of
green building and sustainability movements
•It’s one thing to create a breathtaking lighting layout, but
it’s another to create a breathtaking layout that is also
incredibly energy efficient.
•This can be done by assuring the majority of the light is
reaching its target and there is less wasted light
•Reducing the amount of wasted light will make the
building more efficient

9. Sources of lighting

10. Sources of lighting
Natural Artificial
Sunlight and moon light at night time Electrical lamps
May be in the form of direct sunlight or
diffused light
Fluorescent lamps, incandescent lamps,
sodium lamps, CFL, LED

11. Lighting
Day lighting Artificial lighting
In day lighting, the sources (sun and sky)
condition is given, thus if control is
necessary, it must be in transmission and
distribution
The light source is under the users control
Strongly depends upon location, climate
and building fabric and its control is possible
only by the building itself
It is practically independent of the external
given conditions.
Architectural lighting philosophy – light,
colour, mood, quality of space, aesthetics
Usually used in interiors as per the demand
of the created space
Lighting designs for residence, restaurants,
hotels, hospitals, discotheques

12. Day Lighting

13. Artificial Lighting

14. Day Lighting

15. Properties of Daylight
What is Light?
•Electromagnetic radiation with a narrow visible band
about 380 to 780 nm
• Wavelength determines its color
• Light containing all visible waves is perceived as white.

16. Properties of Daylight
•Human eyes sensitivity varies with wavelength, it is
greatest around 550 nm (yellow)

17. Interaction of light with Physical Surface
•Some materials when exposed to light, transmit a large
part of it – these are referred to as ‘transparent’.
• ‘Opaque’ objects block the passage of light.
•Behind opaque objects there will be no light i.e. it will
cast a shadow.
•‘Translucent’ materials transmit a part of the incident
light, but break its straight passage, scatter it in all
directions, creating diffused light.
•Light incident on an object can be distributed in three
ways: reflected, absorbed and transmitted.

18. Interaction of light with Physical Surface
a. Reflection
b. Transmission
c. Absorption

19. Interaction of light with Physical Surface
•If reflectance = r, absorbance = a and transmittance = t,
then,
r + a + t = 1 (in all cases)
However, in case of opaque objects,
t = 0
Thus, r +a = 1

20. Reflection

21. Reflection
• Light reflected from matt surface will be diffused.
•Most often a mixture of semi diffuse or spread reflection
will occur depending upon the relative magnitude of the
two components.
•White surfaces, r = 0.75, grey surfaces, r is between 0.05
to 0.75 and black surfaces, r = 0.05
•Other materials are selective reflectance that absorbs a
certain wavelength of the incident light and the remainder
will show a colour effect.
Yellow paint Absorbs blue Reflects red, yellow, green
Blue paint Absorbs red and yellow Reflects blue and green
A mix of two Absorbs blue, red and yellow Reflects only the green

22. Photometric Quantities
• It is the measurement of the quantities of light
a. Luminous Intensity (I)
b. Luminous Flux ( )
c. Illuminance (E)
d. Luminance (L)

23. Luminous Flux
•Quantity of light that flows per unit time through given
boundary condition.
• Symbol= F
• Unit= Lumen

24. Photometric Quantities

25. Luminous Intensity
•It is the flow of light in lumen that passes through 1
steradian solid angle taken from the light source in a given
direction.
s
θ
r
• θ= S/r
• 1 Radian= 1 unit arc length/ 1 unit radius

26. Luminous Intensity
• Intensity for given direction= Flux per unit solid angle
in given direction
= /θ in given direction
• Unit (Lumen/Sr)= Candela (cd)
•1 Candela is defined as the luminous intensity of perfect
black body having surface area of 1/60 cm2 when heated
up to the melting point of platinum.

27. Luminous Intensity
• Intensity = Flux/ solid angle
• 1 cd
• 1 cd
= Total flux/ total solid angle
= Total flux / 4π
• Total Flux = 4π Lumen
• Hence, 1 candela of source emits 4π lumen of flux.

28. Illumination (E)
• It is the flow of light (flux) per unit area.
1 Lumen
1 m2
• E= /A
• Unit = lm/m2 or lux

29. Luminance (L)
• It is the measure of brightness of a surface.
1 Lumen
1 m2
Let P be the
reflectance
of the task
• Luminance of task (L)= P x E
• Unit Apostilb (asb)
• L= I/Projected area of source
= cd/m2

30. Relation between Illumination (E) and Luminous Intensity (I)
a. Inverse square law for point source of light
b. Inverse law for line source of light

31. Inverse square law for point source of light
• Luminous intensity= flow per unit solid angle
= Total flux/ Total solid angle
I = Total flux/4π
Total Flux = 4πI
Point
source

32. Inverse square law for point source of light
• Illuminance (E)= Total flux/ Total surface area
= 4πI/4πr2
E= I/r2
This is called the inverse square relationship.
•This is only applicable when the illuminated place is
normal (perpendicular) to the direction of light i.e. When
the angle of incidence, β= 0°.

33. Inverse square law for point source of light
•When the plane is tilted, the same flux of light is
distributed over a larger area, thus the illumination is
reduced.
•The reduction is proportionate to the cosine of the angle
of incidence:
Eβ = En x cosβ
Where, En = illumination on a normal plane
Eβ = illumination on a plane tilted by
β = angle of incidence

34. Summary
Photometric Quantities Significance
Luminous Intensity How much light flows form
the light source at a given
direction
Luminous Flux How much light flows in
total from light source
Illuminance How much light flows
towards task of a unit area
Luminance How bright is the source as
the task

35. Illumination Quality
•In lighting design the designer must ensure light which is
both adequate and suitable for the visual task.
•Suitability in this context would mean the following
qualities:
a. Colour of light
b. Colour rendering
c. Light distribution (direct or diffuse)
d. Freedom from glare
e. Luminance distribution (consideration of surface
qualities together with the lighting of these surfaces)

36. Illumination Quality
•A and B depends upon the light source, subject to choice
in electric lighting but given in day lighting
•Distribution in electric lighting depends on the fittings
and their position
•In day lighting it depends on windows and reflective
surfaces.