Daylight

1. DAY LIGHTING

2. “THE HISTORY OF ARCHITECTURE IS THE HISTORY OF THE STRUGGLE FOR LIGHT” – le Corbusier

3. • Importance Of The Daylight
• Daylight Sources
• Daylight Components
• Daylight Strategies
• Daylight Calculations
DAYLIGHT:

4. Three Components of Daylighting
Design
• Aesthetics (light and shadow, color, view…)
• Human performance (psychology and biology
benefits)
• Energy (sustainable design)

5. What is successful daylighting
design?
• Use of diffuse light from the
sky(view)
• Daylight as primary source of
illumination
• Quality visual environment (glare
and luminance ratios)
• Integration with electric lighting
system
• Appropriate control of natural light
• Energy savings

6. Components of the Natural Light :
 There are three separate components of
the natural light that reaches any point
inside a building:
1. Sky Component (SC) - Directly
from the sky, through an opening such as
a window.
Fig: Components of the Natural Light
Sky Component (SC) depends on:
• Width of the window
• Distance between the point and
window

7. 2. Externally Reflected
Component (ERC) - Reflected off
the ground, trees or other buildings.
Externally Reflected Component (ERC) is small.
The luminance of obstruction is taken as 10-20%
that of the sky
3. Internally Reflected
Component (IRC) - The inter-
reflection of 1 and 2 off surfaces within
the room.
Internally Reflected Component (IRC): is a half
of SC and is therefore significant
7

8. Daylight Component…
 Daylight factor defined as:
The ratio of daylighting illumination on
a horizontal point indoors to the
horizontal illumination outdoors,
expressed as a percentage.
8
For clear sky For cloudy sky

9. Daylight Factor
Where,
• Ei = illumiance due to daylight at a point on the indoors working plane
• Eo = simultaneous outdoor illuminance on a horizontal plane from an
unobstructed hemisphere of overcast sky
The daylight factor is defined as :

10. Design daylighting…
• Factors affect on lighting design for interior
spaces:
1. Building location and orientation
2. Function of the space
3. Space depth
4. Openings size and place
5. Glazing
6. Walls finishing ”reflectance”

11. Daylight systems:
• How to redirect the daylight into spaces??
1. Windows
2. Saw-tooth
3. Monitors
4. Skylight
5. Atrium

12. Vertical windows:
Cross section showing lighting distribution
from a single-sided window installation
•Light level falls off quite quickly
as you move deeper into the
space.
•Useful daylighting will only
reach a distance of 2.5 times
eht fo pot eht fo thgieh eht
enalp krow eht evoba wodniw
fo thgieh ksed a ta nekat yllausu(
60 cm).
• In a standard office building
with a window height of 2.5 m,
this means a maximum of about
5-7 metres .

13. Windows…
The Effect of Windows on Two Sides of a Room on
DF

15. The Effect of Window Shape on DF
• Fig. shows how the DF
varies across a room using
two types of windows, both
having the some total area:
• (a) is for three tall windows,
and
• (b) is for one long, high-level
window.
• Window (a) will give a good
open view, but (b) will
provide more even daylight
illumination.

16.  Cross section
showing how
illumination vectors
become more
horizontal as sidelight
travels deeper into a
space.

17. Skylight :
Double-glazed units and a range of
louvered systems should be used
wherever possible to reduce conducted
heat losses.
Appropriate no. of units is 5% of ceiling
area

18. 




19. English court







20.  Roof Monitor
• Saw-tooth skylight

21. Saw-tooth
Saw-tooth orientation
 Saw-tooth inclination

22.  Saw-tooth preferred dimension
 Saw-tooth reflectors
Saw-tooth

23. Mt. Airy Public Library

24. Atrium
•

25. Mushroom column.
Frank Lloyd Wright

27. Atrium -court

29. Use light reflectors under the light system to defuse the light through the
internal space
Kimbel Art Museum - Louis Kahn

30. REDIRECT THE DAYLIGHT:
• Light shelf

31. Light shelf & ceiling reflectors

32. Reflectors & ceiling reflectors

33. Environmental Systems in Architecture -
Daylight- 2nd lecture
33

34. Interior Finishes - Reflectance
Minimum Reflectance Values

37. Design Consideration
 Environmental factors:
1. Solar heat increases the rate of heat gain or loss of the building fabric.
2. Noise.
So,
• The proper choice of window orientation and suitable sun shading device
or constructions, the solar heat gain can be greatly reduced.
• The use of double glazed window units is able to cope with the noise
problem and reduce significantly the heat gain or loss through the window.
• The DF and consequently the illumination near the window decreases
as the height of the window above the floor is increased

38.  Obstructions:
• Any obstruction (buildings opposite
the window, trees, etc.) decreases
the illuminance in rooms.
• Obstructions which subtend
elevation angles of more than 25-
30o significantly reduce the daylight
penetration.
3. Fenestration:
• The lighting conditions in a room depend
primarily on the fenestration.

39. Artificial light & Daylight factor
• The required quantity of artificial
light input is to achieve an
illuminance at the rear of the room
comparable to, but slightly less
than, the daylight illuminance near
the window. For example:
Artificial light
(lux)
Daylight factor
2500.5%
5001.0%
7501.5%
1,0002.0%

40. Innovated Daylighting Systems
40
•Light Pipes:
The system consists of:
1.COLLECTOR /CONCENTRATOR
2.TRANSPORT SYSTEM
3.EMITTER
The Light Pipe Principle

41. Light Pipes…

44. London Art museum

45. Polla museum in Japan

46. The Heliostat System

47. The Heliostat System

52. (Movable-orientable Glass Louvres)

53. The Glass Louvers may be installed as a movable or fix system.