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Air Conditioning

What is Air Conditioning?

Air conditioning is a mechanical system for increasing the comfort of building occupants throught he filtered supply of cooled or heated clean air

In some cases, such as in laboratories and computer machine rooms, air conditioning is also used to achieve temperature and humidity conditions.

Comfort of Occupants

Comfort of building occupants is effected by three important factors:

An air conditioning system simultaneously controls all three (3) factors in accordance with pre-determined design standards. These design standards suit most building occupants, the remainder feeling marginally too warm, or too cool.

The normally accepted standard for temperature and humidity, which is adopted at Griffith University, is:

It is therefore important to remember to dress accordingly in an air conditioned building, because whatever the conditions are outside, inside the building will feel like Spring.

How does it work?

Griffith University uses primarily chilled water air conditioning systems. Water, chilled to 7 deg.C, is pumped around the campus into buildings, where it is used to cool air in a combination of small fan coil units in individual rooms, and large air handling units located in plant rooms which circulate cooled air throughout buildings in ceiling ducts. In winter, electric heaters located inside air conditioning units heat the air which is then circulated.

Because the sun's heat affects a buildings temperature differently depending on the time of day and position of the sun, buildings are divided into two or three zones on each floor. In Australia, the northern side of a building receives five times more sun during winter than the southern side. Building zones enable conditions to remain roughly constant across the building by cooling some zones more or less than others so that, on average, the building interior is at the same temperature.

What about window units?

Window mounted room air conditioners are not used at Griffith University. These units have several disadvantages, including:

Because of these problems, room air conditioners have never been used by Griffith University and are not permitted by University policy.

Evaporative coolers are also not recommended east of the Great Dividing Range because they rely on evaporation of water to achieve cooling. Evaporative coolers are ineffective in places with high humidity, such as in South East Queensland, however, they do work well in dry arid climates (ie. western parts of Queensland).

Energy

Although it improves occupant comfort, air conditioning uses a lot of energy. The University minimises energy use and cost through a Central Control and Monitoring System. The system is located in Facilities Management and gathers data from each building temperature zone on campus, as well as monitoring overall energy use.

In some cases time switches and movement detectors operate the system only when rooms are in use, thus saving considerable energy. Some systems receive a 'pulse' every few hours which switch the system off in the same way as Energex switches hot water systems off. If you are in a room with this type of system and want air conditioning to be running, simply press the ON switch to reset the system after the pulse.

In the imperial system of measurement, the unit of air conditioning was known as a 'ton' of refrigeration. A ton of air conditioning is the energy equivalent to melting one ton of ice in a 24 hour period. Air conditioning usage on the Nathan campus is therefore equivalent to a 2000 ton glacier melting on the campus each day. Similarly large numbers apply on other campuses.

Legionnaires' Disease

Legionella is a bacteria common in natural water sources, however, it can lead to infection when present in poorly designed and maintained air conditioning systems, especially in cooling towers.

The University maintenance staff undertake a comprehensive preventive maintenance program on air conditioning plant, and systems are tested and cleaned regularly. Testing of water quality is also undertaken regularly. In addition, particular attention is paid during design to ensure systems meet all Australian standards.

A Few Tips

Remember that air conditioning is a mechanical system. It can get out of adjustment or stop completely. If this happens call Maintenance on 8888. Please do not attempt to adjust the grilles or the thermostat as you may make it worse rather than better.

Remember that whatever the conditions are outside, they will be like spring inside. Dress accordingly. In summer, bring a jacket that you might put on if cold. In winter dress in layers to allow for the warmer temperature inside.

Closing your blinds and curtains in direct sunlight is a good idea because it reduces the heat and cuts down the air conditioning load for your room. Close them before you leave at night to help the system achieve optimum conditions in the morning.

Don't leave windows or front doors open. The air conditioning system will work overtime trying to reach the pre-set temperature, and open windows let a lot f dust into buildings. Besides, we don't have enough capacity to air condition the rest of town!

Sitting in front of air inlet or outlet grilles will make you feel cold because of the constant air movement, however, blocking grilles will upset the balance of the system and make it worse somewhere else.
Always remember, if you need assistance, call Maintenance on ext 8888.