How Air Conditioning Systems Affect Humidity

Posted on Oct 1, 2020

We have all been in an air-conditioned home that made us feel uncomfortable. Maybe we felt cold and clammy, or hot and sticky. Either way, it is no fun to feel uncomfortable indoors, especially when going inside to a controlled climate is supposed to help alleviate the discomfort from whatever Mother Nature is doing outdoors. Your HVAC system plays a big part in the indoor climate in your home. Not only does it affect the temperature, but it also impacts the humidity level inside. Your air conditioning system will affect humidity in your home, and vice versa.

If your air conditioning is working correctly, the humidity level in your home should be fairly low. According to Energy Star, the ideal indoor humidity level is between 30 percent and 50 percent. This changes based on the room and the season. A bedroom should be about 50 percent relative humidity year-round to improve sleep and reduce allergens. In the rest of your house, you should be at a higher humidity level in the summer, and a low level in the winter. 

The problem is how to control humidity levels throughout the year. What can you do to manage humidity levels, and how can you lessen or increase these levels throughout the year?

How Your Air Conditioning Affects Humidity 

In hotter climates, like here in Hawaii, the air is typically more humid. However, if your AC is working properly, your home should not be uncomfortably humid. Your air conditioner can affect your humidity though. If your AC unit’s capacity is significantly too large for your home or building, it may cool too quickly in short, less effective cycles. Because the unit is turning on and off frequently, the air passing through the unit does not have enough time to dehumidify. 

How to Tell if You Have Excessive Humidity in Your Home 

There is probably no meter on your thermostat to let you know if the humidity level is too high in your home. However, there are a few signs that humidity levels are too high, such as: 

  • Visible condensation on cool surfaces, such as windows, mirrors and out-of-the-way pipes 
  • Wet stains, moisture-related discoloration or crumbly stucco on your ceiling
  • Excessive peeling paint or creaking floorboards (more than usual wear-and-tear)
  • Elevated symptoms of allergies while in the home, such as chronic cough, wheezing, headaches or shortness of breath 
  • Soft or moist walls, floors, shelves or other surfaces

Dangers of High Humidity 

Here in Hawaii, when we go outside in the summertime, it can feel quite humid. At the time, that might not feel like a bad thing (especially with our beautiful breezes and beaches!) But when that moisture is trapped in your home, it can be a threat to the building as well are your health. Some of the dangers of high humidity in your home include: 

Damage To House Interior

If water and moisture is accumulating on surfaces, it can cause long term damage. Mold may form in window sills. Walls, ceilings and floors may sustain discoloration or damage. The integrity of wood or other soft building materials may be damaged. 

Additional Pollutants

Dust, pollens and debris cling more easily to moisture in the air, so if your home is too humid, it could also mean the air in your home contains more pollutants. Dryer vents leaking or getting damaged is a large source of excess humidity and debris being thrown back into your home.

Discomfort Due To High Humidity

Ever felt a cold sweat? Or maybe clammy all over? Or even a sticky feeling on your skin? All of these uncomfortable sensations can be caused by humidity, and none of them feel good! 

Managing Humidity 

There are several ways to manage humidity levels in your home.

Air conditioning system 

Like we discussed above, your air conditioning system is the main way to manage the humidity level in your home. These systems do not just cool the air down inside the building, but as air runs through the system, it removes moisture and humidity. However, make sure the HVAC system you have at your home is the right size for your property; otherwise, it could make the problem worse. 


There are several ways to use a dehumidifier in your home to manage humidity. Dehumidifiers can be installed on HVAC units by a professional to pull water from the air before it is sent back through the ducts. Stand-alone dehumidifiers can also be placed in the home to manage humidity on a room-to-room basis. 

Proper ventilation 

Make sure that areas where water is commonly present, like bathrooms and kitchens, are properly ventilated. Leave vents and fans on whenever there is moisture in the room. 


Weatherstripping, caulking and insulation all help to seal a room or appliance to prevent temperature-regulated air from escaping or excess humidity from seeping in. This is a big one here in Hawaii, where it is warmer outdoors. 

Adjusting AC Unit for Humidity Control 

Are you having issues with humidity, and suspect your air conditioning unit may be to blame? Contact the team at Airpro Indoor Air Solutions to have an air conditioning expert check out your system. Contact us today to set up your appointment.

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