This document discusses ventilation and HVAC systems. It defines ventilation and explains why it is important for human respiration, diluting odors, removing combustion products, and providing a comfortable thermal environment. It describes natural and artificial ventilation systems. For artificial systems, it covers exhaust, plenum, exhaust-plenum, evaporative cooling, air conditioning, and different types of HVAC equipment. It emphasizes the functional requirements of an effective ventilation system.

1. Air Conditioning & HVAC Systems
Building Utility & Services

2. Syllabus
Air Conditioning and HVAC systems:
Conventional Systems and its types, HVAC
Systems-Ventilation energy efficiency, air
filtration and cleaning, Introduction to HVAC
Industrial Standards, Heating for comforts-
boilers and furnaces

3. Ventilation
• It may be defined as supply of fresh outside air into
an enclosed space or the removal of inside air from
the enclosed space. Ventilation may be achieved
either by natural or artificial means.

4. Ventilation
• Ventilation is essential for the following reasons:
• For Human respiration
• To dilute air to prevent vitiation of body heat and
odors.
• To remove product of combustion
• To provide such thermal environment as will assist in
the maintenance of the heat balance of the body in
order to prevent discomfort and injury to the health of
the occupants
• To prevent suffocation condition in conference rooms,
committee halls and cinema halls.

5. Ventilation

6. Ventilation

7. Functional Requirement of Ventilation
• Ventilation system provided for any building should meet
the following functional requirements
• (a) Humidity
• Air contains certain amount of water vapor or humidity in
it relative humidity is defined as the ratio of amount of
water vapor if the air is saturated at the same temperature.
Thus, the relative humidity of saturated air is 100 %.
Relative humidity within the range of 30 to 70 % at the
working temperature of 21 0C is considered to be
desirable.
• For higher temperatures, low humidity and greater air
movements are necessary for removing greater portion of
heat from the body.

8. Humidity

9. Functional Requirement of Ventilation
Quality of Air
• The air habitat room should never contain
more than 0.06 % of CO2, this can be
achieved by proper ventilation

10. Functional Requirement of Ventilation
Effective Temperature
• The general temperature difference between
inside & outside is kept not more than 8 0C.
• The effective temperature, affects the human
body, is an index, which combines into a single
value, the effect of air movement, humidity and
temperature. This is a temperature at which a
person will experience sensation of some degree
of cold or warmth as in quite air fully saturated.
The common value of effective temperatures in
winter and summer are 20 0C and 22 0C

11. Effective Temperature

12. Functional Requirement of Ventilation
Air Changes per hour
• The volume of outside air allowed into a room in one
hour compared with the volume of the room. Where
people are working or living, in an enclosed space air
has to be moved or changed to cause proper
ventilation.
• The minimum rate of air change is one per hour while
the maximum rate of change is sixty per hour.
• Air change per hour is the volume of outside air
allowed in the room or enclosed space per hour
compared to the volume of the room.

13. Functional Requirement of Ventilation

14. Functional Requirement of Ventilation
Recommended Values of Air Changes
• The standard values of air changes are based on control of
body odor or the removal of products of combustion when
no other contaminants are present in the air.
• Living room and bedrooms- Six air changes per hour.
• Kitchen: Minimum three air changes to remove steam, heat
and smell and fumes generated in cooking and to prevent
excessive rise of temperature and humidity.
• Kitchen – restaurants Minimum twelve air changes.
• Bathroom and water closets: minimum six air changes
desirable after use.
• Passages- No need as it is open.

15. Systems of Ventilation
• There are two systems by which desired ventilation
can be obtained-
• Natural and Artificial.
• Natural ventilation is one which is effected by the
elaborate use of doors, windows, ventilators and
skylights. It is suitable for residential buildings and
small houses.
• Artificial ventilation is the one, in which some
mechanical arrangements are made to increase the
rate of airflow. This system is more useful for large
buildings, assemblies, theatres etc. It involves the use
of some mechanical equipment's offering effective air
circulations.

16. Natural Ventilation

17. Artificial Ventilation

18. Systems of Ventilation
• The following systems are normally used-
extraction system, plenum system, extraction-
plenum and air –conditioning.

19. Systems of Ventilation
• Natural Ventilation
• The rate of ventilation by natural means through
windows or other openings depends upon.
• Direction and velocity of wind outside;
• Size and disposition of opening (Wind Action)
• Convection effects arising from temperature or
vapor difference between inside and outside the
room;
• Difference of height between the outlet and inlet
openings

20. Natural Ventilation

21. General Rules for Natural Ventilations
• The following rules are broadly followed for
obtaining the efficient natural ventilation
• Inlet opening in the building should be well
distributed and should be located on the
windward side at a low level and outlet
openings should be located on the leeward
side near the top.
• When outlet serves also as inlets, they should
be located at the same level.

22. General Rules for Natural Ventilations

23. General Rules for Natural Ventilations
• Inlet opening should be free from all obstructions- trees,
buildings, signboards etc.
• Greatest flow per unit area can be achieved when inlet and
outlet are equal in areas;
• Openings may be arranged to take advantage of constant
and dependable stream of winds. In case of variables wind
directions, openings have to be provided in all directions.
• The amount of outside air entering by natural infiltration
through doors/ windows and other openings depend on
direction and velocity of wind outside and /or convection
effects arising from temperature or vapor pressure
difference between inside and outside of the workroom.

24. General Rules for Natural Ventilations

25. Artificial Ventilation
• Artificial ventilation involves the use of some
mechanical equipment's for effective air
circulation.
• It is applied when natural ventilation is
unsatisfactory in respect of quality, quantity and
controllability.
• This system is costly but improves on the
situation extraction (Exhaust), Plenum (Supply),
extraction- Plenum and evaporative cooling and
air conditioning.

26. Artificial Ventilation

27. Extraction System (Exhaust)
• It is based on creation of Vacuum in the room by
exhaust the vitiated inside air by means of
propeller type (exhaust) fans.
• The extraction of air from the room permits the
fresh air to flow from outside to inside through
openings (Windows). The system is more useful
in removing smoke, dust, odors etc. from kitchen,
toilets and industrial plants.
• The exhaust fans are not located near the
windows openings to avoid short-circuiting of
the air.

28. Extraction System (Exhaust)

29. Artificial ventilation
• Plenum System
• In this system fresh air is forced into the room
and the vitiated air is allowed to leave
through ventilators, Air is Passed through a
fine gauge screen or filter.
• A constant stream of water is kept flowing
down the screen by means of a blowing fan.
Thus all impurities are removed from the air,
and one can get fresh air.

30. Plenum System

31. Artificial ventilation
Celling Fans
• Almost all types of houses and offices use fan in
bedrooms, living rooms and offices area.
• Variety of fans like ceiling, table mounted, and
wall mounted, pedestal fans are available in the
market. Air circulation by ceiling fans cover
normal area of 9 to 10 sq. m. Ceiling fans are
widely used in all premises for the purpose of
ventilation. The ceiling fans are effective only
over certain limited areas

32. Celling Fans

33. Artificial ventilation
• Extraction –Plenum System
• This is an extension of plenum system in
which extraction (Exhaust) fans are used for
exit of the vitiated air from the rooms and
fresh air supplied through system.

34. Extraction –Plenum System

35. Artificial ventilation
• Evaporative Cooling
• Evaporative cooling is used in the region where
high day temperature prevail with reasonably
low humidity.
• This system may be employed effectively to lower
the temperature of the air to near the wet bulb
temperature.
• It produces an air supply cool enough to take
care of the indoor sensible heat loads without
exceeding the upper safe limits.

36. Evaporative Cooling

37. Evaporative Cooling

38. Artificial ventilation
Air Conditioning
• It is the process of treating air so to control
simultaneously its temperature, humidity, purity, and
distribution to meets the requirement of the
conditioned space.
• W.H. Carriers who is known as the ‘Father of Air
Conditioning’ engineered and installed the first year
around air conditioning system, providing for the the
major functions of heating, cooling, humidifying and
dehumidifying. He made use of air washers for
controlling the dew point of air by heating or chilling
recirculate water.

39. ‘Father of Air Conditioning’

40. Air Conditioning

41. Air Conditioning
• Carrier Presented ‘ Rational Psychometric
Formulae/ Related to the dry bulb, wet bulb,
and dew point temperature of air with its
sensible, latent and total heats and presented a
theory of adiabatic saturation.

42. Air Conditioning
• Moist air is the working substance in air-
conditioning system. It is a mixture of two
gases dry air and water vapor.
• Dry air is a mixture of a number of gases and
water vapor may exist in a saturated or
supersaturated state. Dry air is considered as
fixed part and water vapor is considered as
the variable part.

43. Air Conditioning

44. Air Conditioning
• Therefore, the air conditioning must be able to
vary the temperature and humidity of the air
conditioning space according to the outside
conditions. That means:-
• In hot arid regions it must reduce temperature
and increase humidity;
• In hot-humid regions, reduce both temperature
and humidity;
• In cold humid regions, increase both
temperature and humidity

45. Air Conditioning

46. Air Conditioning
• Air Circulation is the best system of artificial
ventilation in which provision is made for
filtration, heating or cooling humidifying etc.
Thus creating most comfortable conditions.

47. Air Conditioning
• Air Conditioning helps in the following ways-
whether for comfort air conditioning or
industrial air- conditioning;
• Preserving or maintaining health, and comfort of
human beings;
• Comfortable entertainment in theatres, assembly
halls;
• Journey on roads/ rails become comfortable.
• Improving the quality of industrial products,
such as artificial silk, cotton cloth, etc.

48. Air Conditioning
Summer Air Conditioning
• In summer, outside temperature is more, and
hence cooling of air is required for greater
comfort. The cycle of operations consists of air
cleaning, air cooling, dehumidification and
air distribution/ Circulation.

49. Summer Air Conditioning

50. Air Conditioning
Winter Air Conditioning
• In winter, outside temperature is low and
hence heating of air is required for comfort.
The cycle of operation consists of air cleaning,
air heating, and humidification and air
distribution/ circulation.

51. Air Conditioning

52. Air Conditioning
Composite Air Conditioning:
• In this, the same air conditioning is done
throughout the year, irrespective of outside
temperature.

53. Air Conditioning
Systems of Air conditioning
• All air conditioning systems can be broadly
classified in two categories-
• Direct expansion systems ( DX systems) and
Chilled Water ( Indirect ) Systems.

54. Direct expansion systems
( DX systems)

55. Chilled Water ( Indirect ) Systems

56. Air Conditioning
Direct Expansion System
• It is the system where the refrigerant is
utilized to cool the air directly the common
example are room air conditioners, packaged
units, and central direct expansion plants.

57. Room Air Conditioner
• A room air conditioner is a factory made assembly
designed unit for mounting on a window, through a
wall,.
• It is designed to deliver conditioned air without ducts.
• It is the prime source of refrigeration and
dehumidification and circulates and cleanses the air. It
may also include means for ventilation and heating.
Normal capacities of room air conditioners in KWH
are 1 tonne to 10 tonne. Electrical consumption is a
critical performance factor in air conditioning.

58. Room Air Conditioner

59. Room Air Conditioner
• Purifying filters and de-odouring filters are just
some examples of the extra filters provided to
convince consumers of the better performance
and capacity to these filters. The function of the
main filter is mainly to protect several
components inside the system, of large particles
that may get inside the appliance and damage it.
• The constant humming sounds of the AC, even if
not very loud ( between 44 dB to 51 dB); can be
quite annoying to the ear.

60. Room Air Conditioner

61. Room Air Conditioner
• While Installing an air conditioner, its place of
installation is an important criterion, which
affects the performance of the air conditioner.
• An AC should optimally distributed air with the
same air speed and temperature in all points of
the room. This allows for even cooling of the
room.
• An AC should be located on shady side of the
house or building and direct sunlight does not
fall on AC as this reduces its efficiency. An AC
should be protected from dust and rain.

62. Room Air Conditioner
Packaged Air Conditioners
• It comprises of a compressor, water cooled condenser,
evaporator and fan and all mounted in a sheet metal
cabinet.
• They are ideally suited for residence, shops, banks, offices
and some industrial applications. Window units are
available up to a limited capacity.
• For large capacities floor mounted self-contained packaged
units are made to meet to meet the requirements. They are
normally mounted on a resilient pad, which prevents
vibration of the compressor from being transmitted to the
building. It is used for both comfort purpose as well as
process control of temperature and humidity for
manufacturing purposes.

63. Packaged Air Conditioners

64. Room Air Conditioner
A split air conditioning System
• It has a coil and fan inside the room and the
nosier components ( the compressor, fan and
condenser) are on the outside.
• Split air conditioners are slightly more expansive
to buy and install, but they are much quiter on
the inside, more versatile than conventional
types, and if you need air conditioning in more
than one room, some models have an outside
unit that can supply two or more fan/coils units
on the inside.

65. A split air conditioning System

66. Air Conditioning
Indirect Expansion
• In this system chilled water is produced in the
refrigeration plant housed in the main plant room. Chilled
water is then carried through insulated chilled water
piping to air handling unit or fan-coil unit, where the
return air and the fresh air mixture is filtered, cooled and
dehumidified and then distributed to the conditioned space
through galvanized iron and aluminum ducting and grills/
diffusers.
• The return air is brought back to the air handling unit
through the annular space formed around the supply air
duct and the false ceiling enclosure. Here it is mixed with
the fresh air or ventilation air and then passed through the
filters and the cooling coil.

67. Air Conditioning

68. Air Conditioning
• There are two types of systems in common use-
using air for heating and cooling and using
water and air. The former include fixed and
variable air volume systems, while the latter
include combined system using air for
ventilation along with the coils at such zone for
heating and cooling. The central air conditioning
system consists of four main parts:
• Central plant; distribution system; terminal
devices and controls.

69. Air Conditioning
• In a fixed volumetric flow rate air systems of
heating and cooling an outside fresh air flows
through the filter, cooling coil, humidifier and
fan to the conditioned space.
• The system is more useful for factories, hotels,
assembly halls, and big residential buildings
where it is un-economical to install separate
units for each rooms.

70. Air Conditioning
• The main components of this system are the same as
direct expansion system but a chiller is the additional
item. The system has the following components….
• Compressor
• Condenser
• Chillers
• Air handling unit with chilled water coil and/or fan
coil unit or chilled water air washers.
• Cooling tower;
• Chilled water and condenser water pumps sets;
• Air distribution ducting and grills.

71. Air Conditioning

72. Heating for Comfort
• In cold region, it is necessary to keep warmth in
the building; therefore some artificial measures
need to be taken.
• The primary sources of heat for buildings
heating-systems are fossil fuels, natural gas, and
various grades of fuel oils and coal.
• Electricity is used under certain circumstances
for heating in commercial buildings including
perimeter zone heating and service water
heating.

73. Heating for Comfort
• The heating plant produces heat and
distribution systems like ducts, fans and
pumps, terminal devices and auxiliary
equipment distributed to the intended places.
The equipment that produces heat are
furnace, boilers and furnaces, heat pumps,
heat exchangers, etc.

74. Heating for Comfort
Furnaces
• Furnaces are used to heat air streams that are used for
heating the interior of buildings. Boiler are pressure
vessels used to transfer heat produced by burning a
fuel to a fluid. The most common fluid used for this
purpose in buildings is water liquid or vapor.
• The key distinction between furnace and boiler is that
air is heated in furnace and water is heated in the
boilers. The fuel used for producing heat in boilers
and furnace include natural gas (i.e.
methane),propane, fuel oil, wood, coal and other fuels.

75. Heating for Comfort

76. Heating for Comfort
• Modern furnaces use forced convection to remove
heat produced within the firebox from its outer
surface. The up-flow design is used in fully sized
mechanical rooms where sufficient floor –to ceiling
space for the connecting ductwork.
• Down-flow furnace works in reverse, airflows,
downward as it is heated by passing over the heat
exchanger. This design is used in residences without
basements or in upstairs mechanical spaces in two
story buildings.
• In addition to natural gas, liquefied propane gas
(LPG) and fuel oils can be used as energy source for
furnaces.

77. Heating for Comfort
Boilers
• A boiler is a device made from copper, steel or
Cast-Iron to transfer heat from a combustion
chamber to water in the liquid phase, vapor
phase or both.
• Boilers are classified both by the fuel used and by
the operating pressure. Fuels include fuel oils,
woods, coal refuse drive fuels, and electricity.
Boilers produce either hot water or stream at
various pressures. Stream produces by boilers is
used in buildings for space heating, water
heating and absorption cooling's.

78. Boilers

79. Heating for Comfort
• Boilers for buildings are classified as – low
pressure and high pressure boilers.
Low pressure boilers
• Steam boilers with operating pressure below 100
kPa and hot water boilers with pressure below
1000 kPa, temperature are limited t 120 0C.
High pressure boilers
• Steam boilers with operating pressure above 100
kPa and hot water boilers with pressure below
1000 kPa, temperature are limited to 120 0C

80. HVAC Standards
• ISHRAE
• The Indian Society of Heating, Refrigerating
and Air Conditioning Engineers (ISHRAE), was
founded in 1981
• ISHRAE’s primary objective is the
advancement of the art and sciences of
Heating, Ventilation, Air Conditioning,
Refrigeration Engineering & other related
Building Services.

81. HVAC Standards

82. HVAC Standards
The codes, regulation as detailed below shall be followed in this
contract :-
• Safety code for air-conditioning (revised) amendment 1 : IS
659 : 1964 (reaffirmed 1991)
• Safety code for mechanical Refrigeration : IS 660 : 1963
(reaffirmed 1991)
• Air-cooled heat exchangers (amendment 1) : IS 10470 :
1983 (reaffirmed 1991)
• Packaged Air-conditioner(amendment 1991) :IS 8148 : 1976
(reaffirmed 1991)

83. HVAC Standards
Safety Codes
• The following IS codes shall be followed:
• Safety code for mechanical refrigeration
: IS 660
• Safety code for air conditioning : : IS 659

84. References
Building Services: S.M. Patil
Internet Websites
http://ishrae.in/

85. Thanks…