Science Behind Wall-Mounted Aircons: How They Cool The Space

Science Behind Wall-Mounted Aircons: How They Cool The Space

Wall-mounted air conditioners have become ubiquitous in modern buildings, offering efficient cooling solutions for homes, offices, and commercial spaces. Understanding the science behind how these units cool the air is essential for optimising their performance and energy efficiency. In this article, we'll delve into the intricacies of heat exchange, compression, condensation, and evaporation that make wall-mounted air conditioners effective cooling devices.


1. Heat Exchange

At the core of a wall-mounted air conditioner's functionality lies the principle of heat exchange. These units employ a refrigeration cycle to transfer heat from indoors to outdoors, resulting in cooler indoor temperatures. The refrigeration cycle involves four primary components: the compressor, condenser, expansion valve, and evaporator.


2. Compression

The cooling process commences with the compressor, a vital component housed within the wall-mounted unit. The compressor's role is to pressurise the refrigerant gas, leading to a significant increase in its temperature. This compressed gas is now primed for the next stage of the cycle.


3. Condensation

The hot, pressurised gas exits the compressor and enters the condenser coil, typically located on the unit's exterior. Here, the gas releases its heat to the surrounding environment, causing it to condense into a high-pressure liquid. This liquid state sets the stage for efficient heat transfer.


4. Expansion

The high-pressure liquid refrigerant then passes through the expansion valve, where its pressure is rapidly reduced. This sudden drop in pressure induces the refrigerant to undergo a phase change, transforming back into a low-pressure gas.


5. Evaporation

As the refrigerant enters the evaporator coil, situated within the indoor unit, it begins to evaporate. This phase change from liquid to gas is accompanied by the absorption of heat from the indoor air passing over the evaporator coil. As a result, the indoor air temperature decreases significantly.


6. Continuous Cycle

The cooling cycle is continuous, ensuring a consistent and comfortable indoor environment. Warm indoor air is drawn into the unit, cooled through the evaporation process, and then circulated back into the room. Simultaneously, the heat extracted from the indoor air is expelled outdoors, maintaining thermal equilibrium.


7. Efficiency Enhancements

Modern wall-mounted air conditioners often incorporate features to enhance efficiency and cooling capacity. Variable-speed compressors adjust the cooling output based on the required load, optimising energy consumption. Programmable thermostats allow users to set temperature preferences, while energy-saving modes further reduce power consumption during periods of low activity.


8. Air Filtration

In addition to cooling, wall-mounted air conditioners contribute to improved indoor air quality. Many units are equipped with built-in filters designed to capture dust, pollen, and other airborne particles. This filtration process not only enhances comfort but also promotes a healthier indoor environment.


9. Size and Placement

The size and placement of a wall-mounted air conditioner are crucial factors influencing its performance. An undersized unit may struggle to cool a space effectively, leading to discomfort and increased energy consumption. Conversely, an oversized unit may cycle on and off frequently, resulting in uneven cooling and higher energy bills. Proper sizing and strategic placement ensure optimal cooling efficiency and comfort.



Wall-mounted air conditioners rely on a sophisticated refrigeration cycle involving compression, condensation, expansion, and evaporation to cool indoor spaces effectively. Understanding these fundamental principles can help users maximise their units' performance, enhance energy efficiency, and create a comfortable living or working environment. Additionally, advancements in technology, such as variable-speed compressors and air filtration systems, continue to improve the functionality and sustainability of wall-mounted air conditioning systems. 

If you’re looking for an excellent wall mounted aircon in Singapore, look no further than the HAORI air conditioner! Endorsed with a prestigious 5-star rating by the National Environment Agency (NEA), this aircon boasts the highest energy efficiency, promising to keep your space cool while minimising energy consumption.

One of the key benefits of the HAORI Air Conditioner is its Aqua Resin-coated coils. These innovative coils not only enhance the unit's durability but also act as a barrier against impurities, ensuring that your air remains clean and fresh. 

What’s more, as a part of our Toshiba Trade-in promotion, you can upgrade to the advanced HAORI Air Conditioner and enjoy savings of up to SGD 1000 when trading in your old Toshiba unit. For other brands, we offer generous discounts of up to SGD 800. Plus, with every system purchase, receive complimentary fabric covers of your preferred colour, each valued at SGD 188.

For more details and to experience the excellence of the HAORI Air Conditioner, click here.

Back to blog