Bs mechanical-and-air-conditioning

Introduction
Mechanical ventilation helps to provide fresh air in a building by circulating the fresh air
through ducts and fans rather than relying on airflow through the building’s small holes or cracks
in walls, roofs or windows. Without mechanical ventilation, moisture, odors and other pollutants
can build up inside a building which can reduce the productivity of occupants. This can be
prevented by installing fans directly in walls or windows, or in air ducts to supply into or remove
air from the building.
Air conditioning provides cooling, ventilation and humidity control for all parts of the
building. The use of air conditioning system in a building can provide human thermal comfort,
improved air quality, silent operation, reduce humidity and provide controllable comfort. To
maintain indoor air conditions, air conditioned buildings normally have sealed windows since
open windows counteract the system.
https://www.energystar.gov/ia/new_homes/features/MechVent_062906.pdf
https://www.designingbuildings.co.uk/wiki/Mechanical_ventilation_of_buildings
http://www.airconditioningwellingborough.co.uk/Air-Conditioning-Explained.asp
http://www.advantage-asl.co.uk/news/the-benefits-of-air-conditioning-in-the-workplace

2.0 Mechanical Ventilation: Jet Fan System
Jet fans system is found in the basement or enclosed car parking space of SP Setia
Headquarters where it provides either normal ventilation and also even help extract smoke in the
event of a fire, or a combination of both. The jet fan system includes 3 ventilations elements, the
carbon monoxide detection sensors, a control panel and CFD (computational fluid dynamics)
analysis. These 3 elements are critical for a ventilation system to operate effectively in the car
park.
Jet fans found at the top of the basement car parks in SP Setia HQ
Jet fan system consists of a set of axial impulse fans, which operates similarly to a ducted
system. When it is installed on the ceiling, this system ventilates the air from the top areas to the
bottom areas where it creates a continuous flow of air. The jet fans are able to prevent airs being
trap in certain areas as well as comprehensively purify the air at both the top and bottom layers
of the basement car park.
Basic component of a jet axial system

The jet system is able to easily control areas of the ventilation system in order to reduce
the effects of smokes but only to the area affect by the fire event. This system is also able to
control the overpressure of the firefighting zones and the under pressure of the site of fire , which
stops the smoke from spreading by drastically reducing the temperature of the fire affected
zones.
In the event where the fire starts Jet fan system starts running
The fire smoke is exhausted
http://maico.ae/wp-content/uploads/2013/09/Dynair_Jet_Fab_Carpark_Ventilation_System.pdf

2.1 Centralized Air Conditioning System
SP Setia Headquarter uses a centralized air-conditioning system in the building. This system
consists of two separated parts. It includes the outdoor and indoor unit. The typical outdoor unit
contains electrical components, a condenser coil, compressor and a fan whereas the indoor unit
contains the evaporator coil, refrigerant and a thermostat that acts as a temperature control system.
Generated by electricity power, the refrigerant flows through a closed system of
refrigeration lines between the indoor unit and the outside unit. The warm air within a building is
absorbed into ductwork by a motorized fan. After the air is being cooled, it is being transported
through connecting ducts to vents throughout the whole building, cooling down the interior
temperature. The refrigeration cycle repeats itself.
http://www.goodmanmfg.com/resources/heating-cooling-101/how-central-ac-systems-work
http://www.centralcityair.com/how-it-works.html

2.1.1 Refrigeration System Flowchart
In the centralized air-conditioner, the refrigeration cycle is a process where heat is removed
from an unwanted area and transferred to another area. The air conditioner will not produce heat
by itself. For heat to be able to transfer, a temperature and pressure difference must exist at
different places.
The refrigeration system operates by extracting heat from a lower pressure region
(evaporator) into a higher temperature and pressure area (condenser). For example, if the air
surrounding the evaporator is of 35 degree Celsius, cold refrigerant of 25 degree Celsius flows
through the evaporator will cause the cold refrigerant to absorb the heat from the hotter space. By
absorbing the heat from the warm space, it helps cool down the space. The heat is then being
transferred to the condenser through compressor.
http://www.centralcityair.com/how-it-works.html

2.1.2 Packaged Air Cooled Chiller
One of the chillers used in SP Setia Headquarter are packaged air-cooled chillers. A
packaged air cooled chiller usually consists of a tank, pumps and microprocessor controls besides
the basic components such as compressor, evaporator, condenser and expansion valve. Since air
cooled chillers are of closed-loop systems, they make a better process cooling option compared to
water cooled chillers. Closed loop systems allow the chiller to have instantaneous cooling ability
and also helps to save water significantly by recirculating the coolant.
The designed air cooled chillers used are easy to operate. The ‘plug and play’ design closed
loop systems are used because this design helps to reduce maintenance cost for the building and
overall, lowers down the lifetime cost of the unit. Regular maintenance of the air-cooled chillers
includes cleaning of condenser, ensure proper air flow around the unit and making sure the PH
level of water is maintained at 7.
The cycle of an air-cooled chiller starts in the evaporator, where a liquid refrigerant is
allowed to flow over the evaporator tube bundle and evaporate, letting the heat absorbed from the
chilled water circulating through the bundle. The compressor then draws out the refrigerant vapor
from the evaporator. The refrigerant vapor is pumped into the condenser by the compressor to raise
its temperature and pressure. Then, the refrigerant condenses on the condenser tubes, releasing its
heat to the cooling air. The high pressure liquid refrigerant from the condenser will pass through
the expansion device that reduces the refrigerant pressure and temperature as it enters the
evaporator. Lastly, the refrigerant is allowed to flow through the chilled water coils to absorb more
heat and completing the cycle.

This is the microprocessor control within the chillers. Having a microprocessor control
allows the system to be more precise. It offers more accuracy and durability compared to other
types of control system.
http://www.coolingtechnology.com/about_process_cooling/water-cooled-chiller/
These are the condenser and
evaporator. The refrigerant enters the
condenser in a superheated state and
changes from vapor to liquid as most of
the heat is being released into an
external space.
Cold water tank storage in SP Setia Headquarter

Chiller pump
To maintain a chiller system in its best condition, the compressor oil is replaced annually
and the air filter must be cleaned thoroughly every month to make sure clean air is produced
when it goes through the filter. The refrigeration system has to be shut down daily by the end of
the day to avoid overheating.
http://www.iklimnet.com/expert_hvac/cooling_tower.html

2.1.3 Cooling Tower
A total of 5 cooling towers are found on the rooftop of SP Setia Headquarter. Cooling towers
known as evaporative coolers, used in centralized air-conditioning to cool down warm water from
a chiller condenser. They are installed on the rooftop to allow optimum ventilation. It uses
evaporation of water to release heat from the system. The heat from within the building is
transferred to chilled water, which is then transferred into the refrigerant then to the cooling water.
The heat within the cooling water is removed by allowing it to make contact with moving air.
Water is usually dispersed and allowed to drizzle from a certain height by gravity

The inside of a cooling tower consists of components such as a fan, fan motor and guard,
sprinkler, pipe, suction tank, outlet etc. Each of the components have their specific function that
work together to ensure the cooling tower is functioning properly. The diagram bellow shows the
inner parts of a cooling tower.
Basic principle of the cooling tower system work

2.1.4 Air Handling Unit
Inside AHU room of SP Setia Headquarter
There are a total of 32 Air Handling Unit rooms in the building. Each floor has 3 AHU
except Level 7 that has 4. Air handling unit purpose is mainly to re-condition and circulate air as
part of a heating, ventilating and air-conditioning system. Air handling unit is used to re-
condition outside air that is taken in and then release the fresh air into the building. Since all the
exhaust air is removed, it makes it an acceptable indoor air quality. The fresh air being released
is either heated by heating coil or cooled by cooling coil, depending on the desired temperature
for the re-conditioned air for the building.

The air handling unit is a large metal box that contains separate ventilators for supply and
exhaust, heating and cooling coils, heating and cooling recovery systems, sound attenuators,
mixing chambers, air filter racks and dampers. Air handling units have ductwork that is linked to
them to allow distribution of conditioned air through the building and return to the air handling
unit. To conserve energy, increase capacity and at the same time reduce costs, a heat or cooling
recovery exchange is installed in the air handling unit. Air handling units are usually designed
for outdoor purposes, especially on roofs of a building. Hence, it is also known as a rooftop unit
(RTU).
The air handling unit consists of components such as:
1. Supply Duct
2. Fan Compartment
3. Vibration Isolators
4. Heating and/or Cooling Coil
5. Filter Compartment
6. Return air duct
http://uk.grundfos.com/service-support/encyclopedia-search/air-handling-unitahu.html

2.2 Control
2.2.1 Multi-Zone Variable Air Volume (VAV)
SP Setia Headquarter uses multi-zone variable air volume (VAV) in the server and
control room of the building only. This system is used because it consume less power and since
underfloor air distribution system is more suitable to be use in a much larger area. Besides that,
their server and control room requires a 24-hour use of air conditioning system compared to
other parts of the building.

2.2.2 Underfloor air distribution
SP Setia Headquarter uses underfloor air distribution (UFAD) as a strategy to provide
ventilation in their building as part of the HVAC system. This system is used on every floor
except for the control server room zones. Underfloor air distribution system provides conditioned
air from the air handling unit (AHU) through floor diffusers by using the underfloor plenum
beneath a raised floor. The conditioned air then forms a reservoir of fresh cool air by spreading
across the floor. Contaminated air or heat sources is lifted to the high level to be discharged from
the space. Due to air supplied in much closer proximity to the occupants, the supply air
temperature is much higher compared to the conventional overhead system. A task/ambient
conditioning (TAC) system is used which enables the users to control the thermal comfort
conditions in their local environment.
Swirl Floor diffuser
An illustration of how conditioned air is distributed and returned in SP Setia HQ
https://www.designingbuildings.co.uk/wiki/Underfloor_air_distribution_UFAD
https://www.cbe.berkeley.edu/underfloorair/techoverview.htm

2.2.3 Diffuser
SP Setia Headquarter uses only 2 types of diffusers which are the floor swirl diffuser and
the ceiling diffuser. The ceiling diffuser is only installed at first floor lobby area while the floor
diffuser is installed on every other floor of the building. On the first floor lobby, the floor
diffuser act as the supply diffuser which helps to distribute conditioned air directly to the
breathing zone. The ceiling diffuser act as the return air diffusers which functions to extract
warm air from the area back to the air handling unit (AHU). On the other floors, the floor
diffusers act as both the supply and return air diffuser.
Floor Swirl Diffusers Ceiling Diffusers

Bs mechanical-and-air-conditioning

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