Air conditioning participles, air conditioning systems, heat pumps and heat recovery devices, health considerations and AC related illnesses. Intruder alarms and lightning protection units

1. AIR
CONDITIONING
BY GROUP FOUR

2. GROUP MEMBERS
NAME REG. NO
ADOCH ELSIE 16/U/15
KALOKWERA SAMUEL 16/U/333
KALULE SILAS 16/U/ 5282/PSA
MULONDO JAFALI 16/U/7558/PSA
MUNGULENI SERAPHINE 16/U/1908
WAMALA RONALD 16/U/1261

3. TOPICS TO BE DISCUSSED
No. TOPIC No. TOPIC
1. Air conditioning-
Principles
9. Chilled Beams and
Ceilings
2. Central Plant System 10. Cooling systems
3. Air Processing Unit 11. Refrigeration and system
characteristics
4. Humidifiers 12. Packaged Air
Conditioning Systems
5. Variable Air Volume 13. Heat Pumps
6. Induction (Air/Water)
System
14. Heat Recovery Devices
7. Fan Coil Unit and
Induction Diffuser
15. Health Considerations
8. Dual Duct System 16. Building Related Illnesses

4. Air Conditioning
• This refers to keeping the air in a dwelling cool and dry, for the
comfort of occupants regardless of season and external
atmospheric conditions.
• While ventilation refers to ensuring air changes, air
conditioning focuses on regulating the temperature and
humidity of the air, with;
Internal air temperature between 19 -230C
Relative humidity(RH) between 40 and 60%.
• The air is moved through ductworks and regulated by various
scientific and physical processes

5. Needs assessment for air conditioning
• Building usage involving high heat gains
• Effectively sealed buildings
• Core areas remote from natural ventilation
• Large occupancies
• Confined space, with activities of intensive and high precision
character
• Essentiality of exclusion of airborne dust
Air conditioning involves both heating and ventilations and so, when
used, heating by radiation or opening of windows is not necessary.

6. Terminologies used in air conditioning design:
• Dew point
• Dry bulb temperature
• Enthalpy
• Entropy
• Latent heat
• Moisture content
• Percentage saturation/ Relative humidity
• Sensible heat
• Specific volume

7. Central Plant System
This system is used to when air condition is to be the same throughout
the room, especially for large dwellings without partitions e.g. halls,
supermarkets, etc.
Categories of central plant system
• Low velocity: Used in large dwellings
• High Velocity: Used in large and high buildings, hence it also uses
high pressure

8. 1. Fresh air inlet
2. Mixing Box
3. Filter
4. Preheater
5. Washer
6. Re-heater
7. Inlet fan
8. Inlet duct
9. Exhaust duct
10.Recirculating Duct
Figure 1: Layout of central plant system

9. Operation of the unit
1. Primary air enters through louvers
2. Secondary air form recirculation duct(75%) mixes with primary
air(25%)
3. Any suspended dust particles are filtered out
4. Air is preheated during cold conditions, e.g. in winter before
humidification
5. water droplets and any dust that escaped filters are removed by
the washer’s zig-zag eliminator plates
6. Air is reheated
7. Air is accelerated into inlet ducts
8. Air is delivered to conditioned space
9. Secondary air is removed
10.Secondary air(75%) moves back to the mixer and the process
continues.

10. Figure 2: parts of the ductworkFigure 3: section through the air processing unit

11. Air conditioning ductwork plan

14. Humidifiers
While in the washer, besides removal of suspended dirt, air can be humidified
or dehumidified depending on weather conditions and humidity.
Humidification
Steam produced from water by several means e.g. boiling, evaporation by fans,
etc is sprayed at 200 to 300 kPa into the incoming air. Besides system
embedded humidifies, there are standalone humidifies on the market as well.

15. Mains steam humidifier, injection type
Stand alone humidifiers

16. Dehumidification
Dehumidifies work by drawing the air across cool coils containing refrigerant,
which condenses the water in the air and collects it in a container.
It is necessary for dump areas like basements, cellars, showers, garages, etc.
Washers should be cleaned regularly to avoid legionnaires disease
cellars Stand alone dehumidifier

17. Variable air volume system (VAVs)
This system is a refinement to the central plant system where air
entering the main unit is conveyed in ductwork to ceiling diffusers
which have thermostatically controlled actuators that can change the
air volume to suit each room load.
Changes in load conditions are catered for not by adjustment of the
temperature of the conditioned air delivered, at constant volume, but
by adjustment of the volume, at constant temperature.
In a large room, several VAVs ceiling units may be controlled by one
thermostat.
The inlet fan may have variable pitched impellers to control
distribution.

18. Variable volume terminal unit
VAV boxes

19. Induction (Air/Water) System
• Air from the central plant is conveyed to individual units, where water is used to
adjust the air temperature accordingly.
• Primary air at high velocity is induced through restrictive nozzles to blend with
secondary air from within the room buy induction units usually placed under
windows.
• A damper (movable iron plate) regulates the volume of room air passing through
a temperature controlled heating coil which may be used with chilled water as
cooling coils in hotter months.
• The system is called a two-pipe induction system if it only does heating, and
“four-pipe change over induction system” if it has additional two pipes for
cooling water as well.

20. Fan coil unit fitted above a suspended ceiling (four pipe)

21. Fan-coil unit
In the place of nozzle injection of air into the induction system, a low
powered fan is used to disperse a mixture of primary and secondary air after
reheating or cooling from an energy
exchanger within the unit.
The fan coil terminals each consist of a chassis which mounts a silent
running fan, either centrifugal or cross-flow (tangential flow), a simple air
filter and either a single water-to-air heat exchange coil or a pair.

22. section through fan-coil unit.
Four pipe fan-coil unit

23. Induction Diffuser
This is located at the end of ductworks and incudes a diffuser and a mixing chamber
in which primary air is mixed with secondary air drawn into a plenum ceiling from
the room below.
section through induction diffuser

25. DUAL DUCT SYSTEM
 Supply air using two ducts of the same size;
o Hot air duct
o Cold air duct
 A mixing box consists of different parts such as;
o Fan
o Attenuators.
o Dampers.

26. An illustration of a mixing
box

27. An illustration of Dual Duct
system

28. CHILLED BEAMS AND CEILINGS
 Chilled beams work based on the principle of natural
convection
 Chilled beams are of two types: Active and Passive
chilled beams

29. CHILLED BEAMS AND CEILINGS
 Chilled ceiling rely more cooling and heating by
radiation rather than natural convection as compared to
chilled beams

31. CHILLED BEAMS AND CEILINGS
 Advantages
o They are quieter than air based HVAC systems
o Less energy is used
o Less maintenance
 Disadvantages
o The slab concrete chilled ceiling leads to an increased
thermal mass that makes response to thermostatic
control.
o There may be “indoor” rain

32. COOLING SYSTEMS
 There many types of cooling systems and these include;
o Refrigeration
o Air cooled condenser
o Water cooled condenser

33. REFRIGERATION
 The process consists of:
o a refrigerant
o expansion valve
o evaporator
o compressor
o condenser
 It has three main types or methods namely;
o Vapor compression
o Absorption
o Thermoelectric

34. An illustration of
refrigeration method

36. Refrigerants
 A fluid used in energy exchange in a refrigerating or
heat pump system.
 It absorbs heat, then compressed and finally condensed.
 Examples may include
o Water
o Air

37. Characteristics of refrigerants
 Based on Thermodynamics:
o High latent enthalpy of vaporization
o Low freezing temperature
o Low condensing pressure
 Physical and chemical properties:
o Good heat transfer
o Low water solubility
o Inertness and stability
 Safety:
o Non flammability
o Non toxicity

38. AIR COOLED CONDENSER
 Efficient operation of the refrigeration system depends
on maintaining condenser temperature at an optimum
level.
 The cooling medium can be either water or air
 Advantages
o Smaller heat exchange is required
o No skilled maintenance is required
o No water supply required.
 Disadvantage:
o Bulky

39. An illustration of air cooled
condenser

40. Water cooled condenser
 This has two types namely;
o Natural draught
o Mechanical draught
 The system is usually located on the top of the building,
more common are evaporative atmosphere cooling
towers.

41. Natural draught

42. Mechanical draught

43. PACKAGED AIR CONDITIONING
SYSTEMS
 Preassembled from the factory for direct
installation at site
 Reduces time wastage and costs for installation
 Less labor required in installation
 Contain a vapor compression cycle refrigeration
system comprising of a fan, filters, compressors,
condenser and evaporator coils for cooling
 Humidification is through condensation from the
Direct Expansion refrigeration coil supported in
the air intake

44. Types of packaged air
conditioning systems
This is based on the arrangement of the components
1. Self-contained (single) package
 All components in one housing unit
 May be free standing or attached to the wall
 For relatively small rooms

45. Types of packaged air
conditioning systems
2. Split (double) package
 Indoor air handler consisting of a fan, filter,
evaporation valve and evaporator
 Outdoor condensing unit consisting of a condenser,
fan and compressor
 Both connected by insulated refrigeration
pipework and control tubing

47. Categories of packaged air
conditioning units
This is based on where the units are located on, in or
around the building
1. Window units
 Either mounted below a window or fixed into the
external wall of each room that needs one

48. Categories of packaged air
conditioning units
2. Floor-type and ceiling type packaged units
 Floor type packaged units - usually located on the floor
or suspended slightly above the floor
 Ceiling-type - close to the ceiling or even connected
directly to the ceiling

49. Categories of packaged air
conditioning units
3. Roof type packaged units
 Part of the packaged unit is located on the roof top of
the building

50. HEAT PUMPS
 Heat pumps are designed to move heat from one fluid
to another.
 A heat pump must be energy efficient .
 A heat pump works on principle of a refrigeration cycle
operating in reverse by extracting heat from a low
temperature source and upgrading it to a higher
temperature.

51.  A measure of theoretical coefficient of performance can (COP) can be
expressed as:
𝐶𝑂𝑃 =
𝑇𝑐
(𝑇𝑐 − 𝑇𝑒)
 Where: Tc = condenser temperature based on degrees Kelvin (°C=273K)
 Te = evaporator temperature based on degrees Kelvin
 E.g. Tc =6°C, Te =2°C
 This means that 1KW absorbed is capable of producing 5.74KW

52. MODE OF OPERATION

53. MAIN SOURCE OF HEAT PUMPS
 It originates from the natural low heat in water, air and ground with the
following main processing components such as the source, the pump and
the transfer.

54. BUILDING RELATED ILLNESSES
 Legionnaires disease
 Humidifier fever
 Sick building syndrome

55. SECURITY INSTALLATIONS IN BUILDINGS

56. INTRUDER ALARMS
● Micro-switch
● Magnetic reed
● Radio sensor
● Pressure mat
● Taut wiring
● Window strip
● Acoustic detector
● Vibration, impact or inertia
detector
● Ultrasonic
● Microwave
● Active infra-red
● Passive infra-red

57. MICRO SWITCH
 A small component which is easily located in door or window
openings.
 It is the same concept and application as the automatic light
switch used in a vehicle door recess, but it activates an alarm
siren.
 A spring loaded plunger functions in a similar manner to a bell
push button in making or breaking an electrical alarm detector
circuit.
 The disadvantage is the constant movement and associated wear,
exposure to damage and possible interference.

58. MICRO SWITCH IMAGES

59. MAGNETIC REED
It is comprised of two parts
One is a plastic case with two overlapping metal strips of dissimilar
polarity, fitted into a small recess in the door or window frame. The
other is a magnetic plate attached opposing to the door or window.
When the magnet is close to the overlapping strips, a magnetic field
creates electrical continuity between them to maintain circuit
integrity.
Opening the door or window demagnetises the metal strips, breaking
the continuity of the closed detector circuit.

60. Types of reed switch
 There are two fundamental types, ‘normally open’ and ‘normally
closed’.
 In a normally open switch, the two reeds, which are made from
ferrous material such as a nickel-iron alloy, are positioned so that they
are not touching.
 Normally closed reed switch
A normally closed switch works in the opposite way, when no magnetic
field is present the reeds are in full contact, the electric circuit is
complete and the device is ‘on’. When a magnet is moved close to a
switch, or the switch close to a magnet, the reeds repel one another and
split apart, breaking the circuit.

61. MAGNETIC REED IMAGES

62. Radio sensor, Pressure Mat and Taut Wiring
Radio sensor: these are surface mounted to windows and doors.
 They transmit a radio signal from an integral battery power
source.
 This signal is picked up by a central control unit or receiver,
which activates the alarm circuit. As these sensors are ` free
wired ' they can be moved, which is ideal for temporary
premises or in buildings undergoing changes. A pocket or
portable radio panic button transmitter is an option.

63. Pressure mat:
 These are a ` sandwich ' with metal foil outer layers as
part of a detector circuit. The inner core is soft perforated
foam.
 Pressure on the outer upper layer connects to the lower
layer through the perforations in the core to complete the
circuit and activate the alarm. Location is near entrances
and under windows, normally below a carpet where a small
area of underlay can be removed. Sensitivity varies for
different applications, such as premises where household
pets occupy the building.

64. Pressure mat images

65. Taut wiring:
 also available as a window strip. A continuous plastic
coated copper wire is embedded in floors, walls or
ceilings, or possibly applied around safes and other secure
compartments. As a window strip, silvered wire can be
embedded between two bonded laminates of glass.
Alternatively, a continuous self-adhesive lead or
aluminium tape can be applied directly to the surface.
 In principle, it is similar to a car rear heated window.
When the wire or tape is broken the closed circuit is
interrupted which activates the alarm circuit.

66. Taut wiring

67. Acoustic Vibration and Inertia
Detectors
Acoustic
 Also known as sonic detectors. They are used
mainly for protection against intruders in
commercial and industrial premises.
 A sound receiver comprises a microphone,
amplifier and an output relay. Also included is a
filter circuit which can be tuned to respond to
specific sound frequencies such as that produced
by breaking glass.

68. Vibration Detectors
 A slender leaf of steel is suspended between two
electrical contacts. Hammering or structural
impact produces vibration in the pendulum,
sufficient for the contacts to meet and complete a
detector circuit. Adjustment allows for a variety
of applications, e.g. where a road or railway is
adjacent and intermittent vibration would occur.

69. Vibration detector

70. Inertia Detectors
 These respond to more sensitive movements than
vibrations, so would be unsuitable near roads,
railways, etc.
 They are ideal to detect the levering or bending of
structural components such as window sashes and
bars. A pivotal device is part of a closed circuit,
where displacement of its weight breaks the
circuit continuity.

71. Inertia detector

72. Ultrasonic and Microwave Detectors
 Ultrasonic motion detectors : are electrical devices, which use ultra-
sound (that is, sound of very high frequency) to detect motion. In
such a detector a transmitter emits a sound of a frequency( between 20
and 40 kHz) which is normally too high for the human ear to hear.
 When a receiver picks up the sound waves that is reflected from the
area under protection, it sends it to an appropriate circuit for further
action (normally an audio circuit). In the case of motion of human or
target in the space between the receiver and transmitter, further
change, or shift in the frequency of sound is experienced , a circuit in
the device detects any unusual shift in frequency, which is normally
noted due to predefined frequency.
 A small shift in frequency, such as that produced by an insect or
rodent, is ignored. When a noticeable shift is observed, such as a large
shift produced by a moving person, the device triggers the alarm.

73. Ultrasonic detector

74. Microwave Detectors.
 operates on the same principle as ultrasonic detection.
 Microwaves are the electro -magnetic radiations whose frequency
ranges from 0.3 GHz to 300 GHz. Microwave motion detector.
Microwave motion detectors are one of the motion sensors which
detect the intruder’s motion into a specific portion and triggers
alarm as a consequence. These detectors emit microwaves into
the specific region and detect any intrusion by analysing the
frequency of the received microwaves after the reflection from
the intruder.

75.  The main guiding principle for almost all of these sensors has been the
Doppler’s Effect. A microwave motion detector circuit mainly comprises of
components- the transmitter, receiver and the alarm/related circuit. The
transmitter sends off microwaves into the area. These waves have a
specific frequency. However, as they strike with an intruder moving with a
velocity, the frequency and consequently, the phase of the wave signal
gets altered. Once these reflected waves are received by the receiver, its
phase analysis is done and consequently, an alarm is triggered on if the
analysis depicts some change in the phase of the wave signals. It is worth
mentioning here that the change in phase of the signal wave is directly
proportional to the velocity of the intruder.
 Unlike ultrasonic detectors, microwave detectors are not disturbed by air
currents, draughts and ultrasonic sounds from electrical equipment such
as computers. They are therefore less prone to false alarms.

76. Microwave Detector

77. Active infra-red detectors
• Sometimes also called optical system
• The detector has to main components the
transmitter and the receiver.
• The transmitter emits invisible light beam
acting as a energy source for the cell.
• Any object crossing the beam will effect
alarm due the energy loss in the cell.
• The beam is normally made to pulse
200pulse/ second.

78. limitations of the system
 Illustration of the operation
the system.• Not suitable for
external use
though one of its
advantages is that
it covers a wide
range 300m
• When use across
mirror partitions
or reflected
around corners
the intensity is
reduce of beam,

79. Passive infra-red (PIR) detectors
 Detectors use highly sensitive ceramic infra-red
receivers to recognize radiations from moving
bodies.
 The detectors units are mounted on the wall to
receive and concentrate the radiations on to two
sensors.
 The image variation between the sensor generates
a small difference to effect an alarm.
 One of the advantages of this kind of system is the
pattern can be varied to suit specific use.
 It is applied in all domestic units and can be used
in combination with other units.

80. Passive infra-red (PIR) detectors

81. LIGHTNING PROTECTION UNITS.
 Lightning conductors are device develop to provide protection to
the building in case of these thunderstorms.
 It consists of metallic mostly copper taller which is installed on the
building at the time of construction. With one end buried in the
ground, the other end kept expose.
 Main components of the lightning protector unit are
i. Air terminations
ii. Down conductor
iii. Earth conductors
iv. Zone of protection.

82. LIGHTNING PROTECTION UNITS.
 Air terminations: they intercept the lightning strike
discharge.
 Down conductor: provide a low impedance route for air
terminations to the earth.
 Earth conductors: these are required to give the lightning
discharge current a low resistance path to the earth.
 Zone of protection: the volume or space around a
conductor which is protected against a lightning strike.

83. LIGHTNING PROTECTION UNITS.

84. REFERENCES
 Ching, F. D. (2014). Building Construction Illustrated
(5th ed.). New Jersey: John Wiley & Sons.
 Hall, F., & Greeno, R. (2009). Building Services
Handbook (5th ed.). Burlington: Elsevier Limited.
 McCabe, L. E. (2000). Building Design and Construction
Handbook (6th ed.). (F. S. Merritt, & J. T. Ricketts, Eds.)
New York: McGraw-Hill.
 Oughton, D. R., & Hodkinson, S. L. (2008). Faber and
Kell's Heating and Air-Conditioning of Buildings (10th
ed.). Burlington: Elsevier Limited.