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VENTILATION

IMPORTANCE &

PURPOSE

DEFINITION

METHODS OF FIXED

VENTILATION

-Natural inflow & outflow

-Natural inflow & mechanical outflow

-Mechanical inflow & natural outflow

-Mechanical inflow & outflow

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TYPES OF

VENTILATION &

A/C SYSTEMS

- Natural vent.

- Mechanical vent.

TYPES of A/C

SYSTEMS -Split unit

-Centralize unit

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DEFINITION • the process of "changing" or replacing air in any space to

provide high indoor air quality.

(i.e. to control temperature, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide).

• Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air.

• Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical and natural types.

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PURPOSES OF VENT. 1. Maintain the oxygen content in the area

2. Reduced the carbon dioxide content

3. Controlling humidity in a room.

4. Prevent the heat from the outside

5. Prevent the heat intensity of the machines, lighting

and occupants

6. To maximize heat loss in space

7. Eliminate odor and dirty air content

8. Provides freshness and convenience

9. Cooling the temperature in the area.

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TYPES OF VENTILATION SYSTEMS

1. NATURAL

2. MECHANICAL

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a) Wind driven ventilation

b) Pressure driven flows

c) Stack vent / Stack effect

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a) Natural inflow & outflow

b) Natural inflow & mechanical outflow

c) Mechanical inflow & natural outflow

d) Mechanical inflow & outflow

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NATURAL VENTILATION

• process of supplying and removing air

through an indoor space without using

mechanical systems. It refers to the flow

of external air to an indoor space as a

result of pressure or temperatures

differences.

• There are three types of natural

ventilation occurring in buildings:

– wind driven ventilation,

– pressure-driven flows,

– stack vent/ stack effect

natural vent. is generally impractical for

larger buildings, as they tend to be large,

sealed and climate controlled specifically by

HVAC systems. (heating, ventilation, and air

conditioning)

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NATURAL VENTILATION • Occurs when the air in a space is changed with

outdoor air without the use of mechanical systems,

such as a fan.

• Most often natural ventilation is assured through

operable windows but it can also be achieved

through temperature and pressure differences

between spaces.

• Open windows or vents are not a good choice for

ventilating a basement or other below ground

structure.

• Allowing outside air into a cooler below ground

space will cause problems with humidity and

condensation.

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NATURAL VENTILATION

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a) WIND DRIVEN VENTILATION

• Wind driven ventilation depends on wind behavior, on the

interactions with the building envelope and on openings or

other air exchange devices such as inlets or chimneys.

• Occurs when the wind blows toward the house or building and

create pressure.

The front surface of the wind is in the high-pressure or positive.

Surface wind hedges is in low or negative pressure.

Air moves from high pressure zones to low pressure zones.

The higher rate of wind speed will be even more marked

difference in air pressure.

Ventilation through windows, roofs and walls.

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NATURAL VENTILATION

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Wind-induced ventilation uses pressures generated on the building by

the wind, to drive air through openings in the building. It is most

commonly realised as cross-ventilation, where air enters on one

side of the building, and leaves on the opposite side, but can also drive

single sided ventilation, and vertical ventilation flows.

Figure : For a given total area,

ventilation is improved when openings

are well distributed horizontally and

vertically. This is because the openings

are more likely to be at different

pressure. It also leads to better

distribution within the room.

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NATURAL VENTILATION

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b) PRESSURE DRIVEN FLOWS

Wind pressures are generally high/positive on the windward side of a

building and low/negative on the sheltered side. The occurrence and

change of wind pressures on building surfaces depend on:

wind speed and wind direction relative to the building;

the location and surrounding environment of the building;

shape of the building.

For a building with numerous partitions and openings, it is under

various pressures depending on the relative sizes of the openings and

the wind direction. With large openings on the windward face, the

building tends to be under positive pressure. The reverse is true if

the openings are smaller than those downstream.

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NATURAL VENTILATION

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Figure : Air flow around a building

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NATURAL VENTILATION

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c) STACK VENT / STACK EFFECT

• Stack effect is temperature induced.

• When there is a temperature difference between two adjoining

volumes of air, the warmer air will have lower density and be more

buoyant thus will rise above the cold air creating an upward air

stream.

• Forced stack effect in a building takes place in a traditional fire

place.

• Passive stack ventilators are common in most bathrooms and other

type of spaces without direct access to the outdoors.

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Comparison of stack effect in the seasonal climate.

During the summer season (see Figure), the reverse occurs when

indoor temperature is lower than outdoor temperature. Figure shows

stack effect that may occur in different forms of buildings, including a

building with no internal partition, a building with airtight separation of

each storey, and an ideal building with vertical shafts and horizontal

openings.

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Combination of wind pressure and stack effect ventilation. Occurs when strong wind flows towards the opening. The internal

air will be pushed out through chimneys or atrium. Therefore the

contaminated internal air will be replaced with fresh air.

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ADVANTAGES OF NATURAL

VENTILATION

1. Does not require any mechanical appliances.

2. Non operational cost.

3. Non maintenance cost for the appliances/

equipment.

4. Silent processes.

5. Combination benefit of ventilation, lighting

and esthetical value.

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DISADVANTAGES OF NATURAL

VENTILATION 1.The system is uncontrolled:

…in terms of speed & distribution

…high rise building received strong velocity

thus windows should be kept closed.

…slow wind velocity during rainy season

2. Internal temperature cannot be monitored:

…difficult to achieved the required human comfort

temperature.

3. Rate of air humidity is uncontrolled :

…depends on the existing external humidity

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DISADVANTAGES OF NATURAL

VENTILATION 4. Uneven uniform distribution :

…ventilation rate depends on sizes of opening.

…distribution is maximum at the area/space

nearby the opening.

…low ventilation rate for rooms further inside a bldg.

5. Quality of fresh & clean wind cannot be assured

…maybe contaminated from the external harmful

element such as smoke and dust.

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MECHANICAL VENTILATION • through an air handling unit or direct injection to a

space by a fan. A local exhaust fan can enhance

infiltration or natural ventilation, thus increasing the

ventilation air flow rate.

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Typical AHU components:

1 - Supply duct

2 - Fan compartment

3 - Flexible connection

4 - Heating and/or cooling coil

5 - Filter compartment

6 - Return and fresh air duct

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a) NATURAL INFLOW & OUTFLOW

b) NATURAL INFLOW & MECHANICAL OUTFLOW

c) MECHANICAL INFLOW & NATURAL OUTFLOW

d) MECHANICAL INFLOW & OUTFLOW

METHODS OF MECHANICAL

VENTILATION

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Winds enter the room naturally without assistence

from appliances.

Internal air is force out with fan which normally fixed

at the building component such as :

– roof

– wall

– window

Suitable for factory, workshop, assembly hall,

bathroom, kitchen and etc.

The system helps to prevent the contiminated/foul

air from entering the adjacent space.

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1. NATURAL INFLOW & MECHANICAL

OUTFLOW / sistem sari

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NATURAL INFLOW & MECHANICAL OUTFLOW

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• External air brought into the building by

application of suction fan.

• Consumed indoor air will exit naturally through

the openings which positioned at the lower level

of the building.

• The methods allows the external air to be filtered

before entering the internal space.

• Recommended for small factory building,

offices or boiler house.

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2. MECHANICCAL INFLOW & NATURAL

OUTFLOW / sistem bekal

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MECHANICCAL INFLOW & NATURAL OUTFLOW

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• External air enters and exit the internal space by

applications of mechanical fan.

• The building need to be properly concealed from

noise, excessive air pressure and temperature.

• Internal air distribution and temperature can be

control. External air can be filtered before consumed

and the replenishment process could be done

affectively.

• Recommended for internal spaces with problematic

air circulations – i.e: operation theater, cinema or

spaces which required a controlled internal

temperature - i.e: laboratories etc.

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3. Mechanical Inflow & Outflow (sistem seimbang/

kombinasi bekal & sari)

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Gambarajah sistem seimbang

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4. Plenum System

(kombinasi bekal, sari dan seimbang)

• Comprises of air filter, heating and cooling

element into the system.

• The air distributed through ducting system

positioned inside the building.

• Applicable for internal spaces which required a

cooled or hot controlled temperature such as –

hospitals, warehouses, chiller room ,

laboratories etc.

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Gambarajah sistem plenum

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Distribution

to internal

space

Distribution

to internal

space

Air suction

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REQUIREMENT

FOR MECHANICAL

VENT…WHY?

Natural system is

ineffective in terms of

quantity and quality

Building/space location

makes natural vent

impossible – i.e: basement

space or hidden corner

Types of building usage or space

requirements skycrapers, needs

for convenience congested space

(smell, odors) or needs for

temperature control

Safety from surrounding

environment- such as from

contaminated air, hazardous

noise level, light or glare.

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Advantages Disadvantages

Mechanical Vent.

a) Even air distribution

b) Filtered air (Q )

c) Controlled of humidity and temperature

d) Minimized entrance of hazardous air

a) involved initial, operation & m’ce cost

b) extra space to allocate equipment's

c) increase noise level (sound buffer)

d) required power supply & backup systems

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AIR CONDITIONING SYSTEMS

• Air conditioning (often referred to as A/C, AC) is

the process of altering the properties of air

(primarily temperature & humidity) to an occupied

space to improve thermal comfort and indoor air

quality.

• air conditioning can refer to any form of technology

that modifies the condition of air (heating, cooling,

(de-)humidification, cleaning, ventilation, or air

movement). In construction, such a complete

system of heating, ventilation, and air conditioning

is referred to as HVAC.

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Window unit

Split unit

TYPES OF A/C

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TYPES OF A/C Packaged terminals

Centralized System

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SPLIT UNIT

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COMPONENTS

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SPLIT UNIT

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COMPONENTS

SPLIT UNIT

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APPLICATIONS

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SPLIT UNIT

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APPLICATIONS

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SPLIT UNIT

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APPLICATIONS

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SPLIT UNIT

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APPLICATIONS

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SPLIT UNIT

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INSTALLATION

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- Above the door

- Minimum installations set back.

SPLIT UNIT

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INSTALLATION

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- Wall mounted.

- Supported by metal plate

SPLIT UNIT

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INSTALLATION

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- Supportive metal bracket.

SPLIT UNIT

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ADVANTAGES

i. Easy installation. Since there is no ductwork to

install, the units are easy to set up. The indoor unit

can be up to 100 feet away from the outdoor

condenser, yet the only space required is a small hole

in a wall for the copper tubing and control wiring. The

condenser unit can even be positioned on a flat

section of roof if available.

ii. Easy maintenance. Split air conditioning systems are

easy to maintain. They have washable filters and

require only routine cleaning periodically. Outdoor

units are designed for easy access for maintenance

and repair. 43

SPLIT UNIT

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ADVANTAGES

iii. Quiet operation. The indoor units of these systems

are typically quiet enough for libraries, classrooms,

boardrooms, and bedrooms. The outdoor components

can be installed under a window or near a patio

without disturbing anyone.

iv. Heating capability. Most split air conditioning units

provide “climate control” with additional heating as

well, so you can live and work comfortably year-

round.

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SPLIT UNIT

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ADVANTAGES

v. Cost effectiveness. Work well in situations where

rooms only need to be cooled at certain times, i.e;

living rooms during the day and bedrooms at night.

Effective distribution may save cost & energy, since

smaller fan motors are used and individual units run at

different times.

vi. Simple control. Most units come with a remote

control, as well as a wall mounted thermostat, and

temperature control is easy and convenient.

vii. Attractive design. Instead of a big, clunky window

unit you have air conditioning units that blend well into

indoor decor. There is no need to block your windows,

either. 45

CENTRALISE SYSTEM

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COMPONENTS

Central air conditioning plants are used for applications

like big hotels, large buildings having multiple floors,

hospitals, etc- where very high cooling loads are

required.

In the central air conditioning systems there is a plant

room where large compressor, condenser,

thermostatic expansion valve and the evaporator are

kept in the large plant room. They perform all the

functions as usual similar to a typical refrigeration

system. However, all these parts are larger in size and

have higher capacities.

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CENTRALISE SYSTEM

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COMPONENTS

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CENTRALISE SYSTEM

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There are two types of central air conditioning plants or

systems:

1) Direct expansion or DX central air conditioning

plant: In this system the huge compressor, and the

condenser are housed in the plant room, while the

expansion valve and the evaporator or the cooling coil

and the air handling unit are housed in separate room.

The cooling coil is fixed in the air handling unit, which

also has large blower housed in it. The blower sucks the

hot return air from the room via ducts and blows it over

the cooling coil. The cooled air is then supplied through

various ducts and into the spaces which are to be

cooled. This type of system is useful for small buildings. 48

CENTRALISE SYSTEM

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CENTRALISE SYSTEM

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2) Chilled water central air conditioning plant: more

useful for large buildings comprising of a number of

floors. It has the plant room where all the important

units like the compressor, condenser, throttling valve

and the evaporator are housed.

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CENTRALISE SYSTEM

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CENTRALISE SYSTEM

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CENTRALISE SYSTEM

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INSTALLATIONS

The installation process will be different for each job,

depending on your HVAC contractor, the type of unit

you purchase and your home's unique needs and

features.

However, there are some basic procedures you can

count on when having your system installed.

Here are some general installation steps that you

should expect from your contractor:

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CENTRALISE SYSTEM

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INSTALLATIONS i. Dismantle and haul away existing air conditioner materials,

and clear all related debris before starting the new install.

ii. Acquire proper permits and schedule required inspections

from the city where you live.

iii. Install new ductwork (if indicated in proposal), or prepare

existing ductwork for use with the new system.

iv. Properly position and place outdoor air conditioning unit.

v. Make proper, safe connections & determine the correct

sizing for the electrical and refrigeration lines and piping.

vi. Install a new thermostat or reuse the existing thermostat.

vii. Charge and start the new system according to manufacturer

specifications.

viii. Conduct a post-installation check or inspection before final

inspection.

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CENTRALISE SYSTEM

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INSTALLATIONS

Consideration of installation started from initial design

stage taking in factors such as:

Contractor - assessment of the home to determine the

appropriate size for the unit(s). This might also be the

individual who installs the actual a/c unit;

Subcontractor - this might be the licensed individual to

perform electrical service (if the HVAC contractor is not

a licensed electrician), or it could be the individual(s)

who run ductwork and handle the many materials;

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CENTRALISE SYSTEM

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INSTALLATIONS

Labour - if the contractor or subcontractor do not

complete all of the installation work on their own, there

will usually be at least one laborer hired to assist; and

Material - from the a/c Freon refrigerant, the tanks,

recovering machine, and the nitrogen, the costs

associated with a central air conditioner involve many

materials.

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CENTRALISE SYSTEM

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ADVANTAGES:

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CENTRALISE SYSTEM

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DIS-ADVANTAGES:

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