In a constant air volume (CAV) system, the air conditioning system typically maintains a constant supply air volume regardless of the cooling load. This means that if the sensible load (the portion of the cooling load that affects temperature) decreases to 50%, the air conditioning system will continue to deliver the same volume of supply air.
When the sensible load decreases to 50%, several things can happen within the air-conditioned space:
Temperature reduction: With a lower sensible load, the cooling capacity of the air conditioning system may exceed the heat gain in the space. As a result, the air-conditioned space will continue to be cooled, potentially leading to a drop in temperature. This may cause the space to become colder than desired if the cooling setpoint is not adjusted accordingly.
Shorter cooling cycles: As the cooling load decreases, the air conditioning system may cycle on and off more frequently. The system may reach the cooling setpoint more quickly and then shut off until the temperature rises again. This cycling can result in shorter cooling cycles and increased energy efficiency.
Humidity control: In addition to temperature control, air conditioning systems also play a role in humidity control. When the sensible load decreases, the system may still dehumidify the air, even if the temperature remains constant. This can help maintain a comfortable humidity level within the space.
It's important to note that CAV systems are known for their simplicity and are often less energy-efficient compared to variable air volume (VAV) systems or other more advanced HVAC systems. In a VAV system, for example, the supply air volume can be adjusted based on the cooling load, allowing for more precise temperature control and potentially greater energy savings.
In summary, when the sensible load decreases to 50% in a CAV system, the space may continue to be cooled, potentially leading to a drop in temperature. The system may cycle on and off more frequently, and the system may also continue to dehumidify the air, depending on the design and capabilities of the specific air conditioning system.