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Does Air Conditioning Reduce Humidity?

Humidity plays a significant role in our comfort, particularly during warm seasons. While air conditioning is commonly associated with cooling, its impact on humidity is equally crucial to understand.

This article explores how air conditioning affects indoor humidity, shedding light on whether AC systems can truly help make our environments more comfortable by reducing moisture levels.

How Air Conditioning Affects Humidity

Generally speaking, air conditioning does reduce humidity by removing moisture from the air as it cools. The AC’s evaporator coil condenses water vapour from the indoor air, thereby lowering humidity levels.

The ability of ACs to reduce humidity stems from the principles of condensation and evaporation. As the air conditioners cool the air in an HVAC system, it lowers the temperature to below its dew point, the temperature at which air can no longer hold all its moisture. This excess moisture is then condensed on the cold surface of the evaporator coil, much like how droplets form on the outside of a cold beverage.

Factors Influencing Humidity Reduction by ACs

Air Conditioner Capacity and Size

An appropriately sized air conditioning unit is essential for effective humidity control. If the AC is too large, it cools the room quickly but doesn’t run long enough to effectively remove humidity, leading to a clammy environment despite the cool temperature. It’s crucial to choose a unit that matches the size of your space for optimal dehumidification.

Outside Humidity Levels

An outside AC unit in warm and dry weather.

The humidity levels outside your home can significantly impact your AC’s ability to reduce indoor humidity. High external humidity can lead to the continuous entry of moist air into your system, overwhelming it and reducing its efficiency in controlling humidity. Ensuring proper sealing and insulation can help mitigate this issue.

Thermostat Settings

The settings on your thermostat also play a critical role in how well your air conditioner can lower humidity. Setting your air conditioner to a lower temperature does not necessarily enhance dehumidification. Instead, a moderate temperature setting that allows the air conditioner to run longer cycles is more effective in removing moisture from the air, thereby reducing humidity more efficiently.

Air Conditioners vs. Dedicated Dehumidifiers

While air conditioners reduce humidity as a by-product of their cooling process, dedicated dehumidifiers are specifically designed to remove moisture from the air. Dehumidifiers work similarly to air conditioners but focus primarily on regulating moisture levels rather than cooling. They can be particularly effective in areas where reducing excess moisture is needed without a significant temperature drop.

Enhancing Humidity Control

1. Regular Maintenance

Keeping your AC system well-maintained is key to ensuring optimal performance. This includes regular cleaning of the evaporator coil and frequent replacement of air filters. Regular AC maintenance not only maintains efficient airflow but also enhances the system’s ability to remove moisture from the air, crucial for effective dehumidification and ensuring good indoor air quality.

2. Using Hybrid Systems

In areas with excess humidity, combining an air conditioner with a dehumidifier can be particularly effective. Some modern AC systems are equipped with built-in dehumidification functions designed specifically for such environments. This hybrid approach allows for better control of both temperature and humidity levels inside your home, ensuring comfort even in the most humid conditions.

3. Improving Home Insulation

Proper insulation and sealing of windows and doors are essential in preventing humid outdoor air from infiltrating your home. By enhancing your home’s insulation, you can help your air conditioning system maintain more consistent indoor humidity levels. This not only improves comfort but also the efficiency of your AC unit, as it does not need to work as hard to maintain the desired climate.

An HVAC vent is cleaned for better ventilation.

4. Enhance Ventilation

Increasing airflow in your home can significantly aid in reducing indoor high humidity levels. Ensure that areas prone to moisture, like bathrooms and kitchens, are well-ventilated. Installing exhaust fans, opening windows when the weather permits, and using attic vents can all help expel moist air and bring in drier outside air.

5. Utilize Dehumidifiers

For regions with chronic high humidity or specific rooms that retain moisture, such as basements or laundry rooms, using dehumidifiers can be highly effective. Portable or whole-home dehumidifiers can extract moisture from the air, helping to maintain optimal humidity in your home and prevent mould growth and other moisture-related issues.


Air conditioners do reduce humidity as part of their cooling process, but the extent and effectiveness can vary based on several factors including the unit’s size, settings, and the external environment. For those living in particularly humid climates, combining air conditioner with dehumidification equipment might be necessary to achieve the best comfort and air quality levels.