Air-conditioning

Air conditioning systems are generally classified into three main categories based on the method used to condition and distribute air throughout a building. These categories are local comfort cooling systems, centralised air systems, and partially centralised air/water systems.

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1. Local Comfort Cooling Systems

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Local comfort cooling systems are designed to provide air conditioning to individual rooms or small areas. The most common types include:

• Window air conditioning units, which are self-contained systems installed through a window or external wall.

• Split air conditioning systems, where a single outdoor unit can serve up to four indoor units. All connected indoor units must operate in the same mode, either heating or cooling.

• Variable Refrigerant Flow (VRF) systems, which allow one outdoor unit to serve up to eight indoor units. Unlike conventional split systems, each indoor unit can operate independently, providing either heating or cooling to suit the requirements of individual spaces.

2. Centralised Air Systems

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Centralised air systems condition air at a central plant before distributing it throughout the building via ductwork. Common system types include:

• Constant Air Volume (CAV) systems, which deliver a fixed airflow to conditioned spaces.

• Variable Air Volume (VAV) systems, which regulate the airflow supplied to each zone to match changing heating or cooling demands.

• Dual-duct systems, which distribute separate hot and cold air streams, allowing the required air temperature to be achieved by mixing the two before delivery to the occupied space.

3. Partially Centralised Air/Water Systems

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Partially centralised air/water systems combine centrally conditioned air with water-based heating or cooling to improve efficiency and occupant comfort. Typical examples include:

• Fan coil systems and terminal reheat systems, which use water to provide local temperature control.

• Induction systems, where primary air induces room air across water coils to provide heating or cooling.

• Chilled ceiling systems, chilled beams, and displacement ventilation systems, which offer energy-efficient methods of cooling and maintaining indoor environmental quality.

Each of these air conditioning system types is selected according to factors such as building size, occupancy, energy efficiency requirements, flexibility of operation, and the desired level of environmental control.