UWE Bristol Engineering showcase 2015
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Prakash Alagendram<br />
Beng(HONS) - Mechanical <strong>Engineering</strong><br />
Project Supervisor<br />
Dr. Aruna Palipana<br />
A study on existing air-conditioning systems used in houses in Malaysia<br />
Introduction<br />
Nowadays, energy generation is mainly supplied by non-renewable energy sources. Malaysia has a large source of natural gas and coal, thus leading to a large<br />
proportion of energy production. However, these two resources are non-renewable and will decrease eventually. One of the vital environmental issues<br />
resulting from energy consumption is the emission of carbon dioxide (CO 2 ) which causes global warming. In tropical countries, the average energy consumption<br />
of a building reaches 233KWh/m 2 /year in which 60% of it is consumed by air conditioning system. Being a tropical country, Malaysia had about 7.3 million<br />
residential in 2010 and is expected to rise by about 150,000 each year. One of the common factors which affect energy consumption in domestic sectors is<br />
increased number of air-conditioners. Energy consumption increases when more air-conditioners are turned on.<br />
Thermal insulation<br />
A proper insulation material is essential in order to achieve a reduced<br />
cooling load and adequate comfort level. A proper insulation material<br />
will also reduce the emissions from power plant. 77% of the energy<br />
consumption can be saved with the installation of roof and wall<br />
insulation. There are various types of insulation material available in<br />
Malaysia such as fiberglass (rigid), urethane (rigid), Perlite, extruded<br />
polystyrene, urethane, fiberglass-urethane, cellulose, Rock wool and<br />
polystyrene.<br />
Ducted air-conditioning system<br />
Air distribution system would be a<br />
good way in which the cooled air<br />
from the air-conditioning unit can be<br />
distributed uniformly to the rooms or<br />
spaces that need to be cooled. The<br />
main component in an airdistribution<br />
system is duct system.<br />
The duct system carries cold air from<br />
the air-conditioning unit to the<br />
rooms or spaces and carries the<br />
return air back to the air-conditioning<br />
unit for recycling. A properly<br />
designed ducted system can maintain<br />
uniform temperatures throughout<br />
the house efficiently.<br />
Air Handling Unit (AHU)<br />
Air Handling Units (AHU) is a device which is<br />
used to supply and circulate fresh air around<br />
a building, and to remove old dry air as a<br />
part of HVAC. It is usually connected to an air<br />
distribution ductwork. For heating or cooling,<br />
AHU is connected to a boiler or chiller from<br />
which hot or cooled water is received for<br />
heat exchange with incoming air.<br />
Determining the suitable material for<br />
thermal insulation<br />
Polystyrene has the highest energy savings of<br />
92.07% while fiberglass has the lowest energy<br />
savings of 85.54%. Therefore, polystyrene was<br />
selected as the most suitable material for<br />
thermal insulation since it is the most energy<br />
saving option. It can save energy up to 92.07%<br />
with an optimum thickness of 0.139m for a<br />
period of 20 years.<br />
Duct dimensions<br />
The duct dimensions required for the<br />
design of duct system for a doublestorey<br />
terraced house in Malaysia is<br />
shown in table below. Circular ducts<br />
were used for this study because:<br />
Circular ducts are more air-tight than<br />
rectangular ducts.<br />
Installation cost is lower.<br />
Less space is needed for duct system.<br />
Pressure drop is lower in circular duct<br />
system.<br />
Future work<br />
Solar energy is been widely used<br />
in houses in Malaysia and<br />
therefore solar powered airconditioning<br />
system could be an<br />
alternative way of cooling<br />
system. In the future, water can<br />
be used as a refrigerant for this<br />
air distribution design system. In<br />
the future, this design can be<br />
further expanded by designing<br />
ductwork for few houses.<br />
Project summary<br />
This investigation is to find alternative ways of cooling<br />
system which can be used so that it can reduce the<br />
energy demand.<br />
Project Objectives<br />
These alternative ways has to be energy efficient. It<br />
also has to be socially and economically viable.<br />
The alternatives ways of cooling system are as below<br />
• Ducted air conditioning system<br />
• Insulation<br />
• Ways to replace individual small air-conditioners<br />
used in each room/each house by supplying cold<br />
air from a central system to several rooms/several<br />
houses.<br />
Project Conclusion<br />
In this study, the most suitable insulation material<br />
which can be used in houses in Malaysia is<br />
Polystyrene. It has the highest percentage of energy<br />
savings compared to other materials used in this<br />
study. It has an energy savings of 92.07% with an<br />
optimum thickness 0.139m for a period of 20 years.<br />
In a ducted air-conditioning system, a proper duct<br />
size and design is needed to move the right amount<br />
of air to each room/space with less noise. In this<br />
study, the total cooling load required for a doublestorey<br />
terraced house is 5.434 tons (RT). A central air<br />
handling unit (AHU) will be installed in the house and<br />
the cooling air produced in the AHU will be<br />
distributed to various rooms/spaces in the house<br />
through duct. In this study, circular duct was used<br />
instead of rectangular duct.<br />
In conclusion, thermal insulation on walls and ducted<br />
air-conditioning system can reduce the energy<br />
demand and thus achieving the aims of this project.
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