The Presentation includes the Stack effect and Construction Building for proper room comfort

1. NATURAL
VENTILATION

2. Aim-
• To study the application of natural ventilation and techniques used
to minimize external energy and enhance the quality of building.
Objective–
• To study how to optimize natural ventilation in buildings and to
minimize mechanical systems for ventilation
• To study the specific approach and design of natural ventilation
systems which varies and based on building type and local climate
.
• To study the different types of functions and techniques used for
natural ventilation .

3. NATURAL VENTILATION TYPES
WIND
BUOYANCY

4. Wind blows through inlet on windward side
And comes out from leeward side from openings
and roof.
An expression for the volume of airflow induced by
wind is:-
Qwind = K x A x V, (unit: m³/h)
A = area of smaller opening (m²)
V = outdoor wind speed (m/h)
K = coefficient of effectiveness
WIND
multiplying air velocity by
the cross section area of a
duct, you can determine
the air volume

5. *Buoyancy occurs when there is difference in
temperature of outdoor and indoor air
*It can be temperature induced :-
eg. Stack ventilation
*Or it can be humidity induced :-
eg. Cool tower

6. Temperature differences between warm air inside
and cool air outside can cause the air in the room
to rise and exit at the ceiling or ridge, and enter
via lower openings in the wall.
TEMPERATURE DIFFERENCE :-

7. *The cool air is heavy due to its humdity content
and drops down to the indoor area .
*It can be achieved properly with A cool tower or
wind catcher or malqaf and badgir
*Cool tower ventilation is only effective where
outdoor humidity is very low

8. WHAT IS NATURAL VENTILATION ?
Natural ventilation is the process of supplying
and removing air through a space by natural
means it can be achieved with openable
windows or trickle vents.

9. Natural ventilation and air movement can be simply
achieved by ‘structural controls’ as it does not
depends on any form of external energy supply or
mechanical installation.
SECTION SHOWING AIR FLOW

10. WHY NATURAL VENTILATION ?
Natural Ventlilation Started From History According
To The Different Climates
typical section through Shahajahanabad house. to facilitate
the moment of cool air into the house, parapets are build
towards the courtyard

11. double apertures used
for ensuring ventilation
in shahjahanabad houses
window for view
and jali ventilation used
at amber fort
ColumnCourtyard Cooling System-diwan E-khas, Red Fort, Delhi
multi-directional
windcatcher

12. *Then People Started Using
External Energy For Thermal
Comfort.
*Time Passes And It Growned Up
In More Sophisticated Way.

13. *And again due to
energy crises and
complexity of
installation and
for the new line
of evolution
people started
using natural
ventilation

14. *DIFFERENT TECHNIQUES
TO ACHIEVE NATURAL
VENTILATION:-
*Stack effect
*Wind tower
*Courtyard effect

15. *
Stack effect depends on thermal forces and
difference in temperature .
Reason of stack effect :-
*Pressure difference between the outside air and
the air inside the building caused by difference
in temperature
Outdoor air Outdoor air
Section

17. *STACK EFFECT WORK WELL – WINTER
*HIGHER THE CROSS SECTION AREA
GREATER THE STACK EFFECT
*‘MOTIVE FORCE’ – STACK PRESSURE
*STACK PRESSURE CAN BE CALCULATED FROM:-
* PS = 0.0042 × ℎ × ∆T
STACK PRESSURE
IN N/M2
HEIGHT OF THE
STACK IN M
TEMPERATURE DIFFERENCE
IN DEG C

18. * STACK VENTILATION SECTIONS :-
TALL ROOMS TALL ROOMS AT EDGE
STAIRS AS STACKTALL ROOMS WITHIN

19. *
• Air enters in wind tower through openings- cooled
down- becomes heavier and sinks down ( presence
of air movement)
• After whole day air exchange – tower becomes
warm in the evening .
• Tower walls absorbs heat during daytime and
relases at night warming cool night air at night.

20. *
A TYPICAL WIND TOWER SECTION

21. * DIFFERENT TYPES OF WIND TOWERS :-
EVAPORATIVE COOLING
WATER SUPPLY
MULTI DIRECTIONAL WIND CATCHER

22. *
Due to incident solar radiation in A courtyard, air
gets warmer and rises , cool air from ground level
flows through the lower openings
RADIATION TO SKY
LANDSCAPE OR WATER
BODY

23. Air flow in Courtyards

24. * HOW COURTYARD COURTYARD EFFECT WORK:-
In such places night ventilation is not very effective for
cooling and night sky radiation is the only answer.
To facilitate the moment of
cool air into the
house,parapets are not built
towards living area
Parapet towards road side
to avoid outside heat
SECTION OF SAHAJANABAD DELHI

26. *Courtyard in modern building :-
AMERICAN INSTITUTE OF INDIAN STUDIES (GURGAON):-
VIEW
sunken courtyard inside the
building with water body and
landscape
PLAN

27. NATURAL VENTILATION EXTERNAL
FEATURES:-
• Orientation of buildings
• Position of openings
• Cross ventilation
• Size of openings
• Opening types

28. Kings chamber meeting
with ministers kerela

29. *
*As a general rule, thin tall buildings will encourage
natural ventilation and utilize prevailing winds, cross
ventilation, and stack effect.
*Tall buildings also increase the effectiveness of
natural ventilation, because wind speeds are faster at
greater heights
Tall buildings improve natural
ventilation, and in lower
latitudes reduce sun exposure.

30. *
Orienting the building so that
the shorter axis align with the
prevailing wind
While orienting it
perpendicular to prevailing
winds will provide the least
passive ventilation.

31. *
Pairing a large outlet with a small
inlet increases incoming wind speed.
SMALL
INLETLARGE
OUTLET

32. *Opening type:-
Opening can be any type according to the
building type and climatic condition

33. *
Windows or vents placed on opposite sides of the
building give natural breezes a pathway through the
structure.

34. scope –
• to minimize the external energy or mechanical system.
• implementation of natural ventilation system- natural
daylighting can be provided.
• thermal comfort can be acquired with less economical
budget

35. *Disadvantages
Quality
internal air
depend on
external air
No control
over
pollutants
No noise,
humidity and
temperature
control
Depend on
building form
Depend on
external
wind
pressure

36. *