How Does Humidity Affect Air Conditioning?

Is a well-known fact that excess humidity can make you feel hot, especially during the summer. However, can humidity affect air conditioning and heating as well? Based on actual facts and real-life testing, we will examine how moisture correlates with an AC cooling efficiency. At the end of the post, we will also recommend which types of air conditioner you should go with based on the dampness level in the room. Let's begin.


Humidity has a significant impact on the effectiveness of air conditioning and heating systems. When the relative humidity level is too high (above 50%), the AC will have difficulty cooling and reaching optimal indoor comfort. Your home will feel warmer than it actually is. Below are a few clear signs of high indoor humidity:

  • Mold and mildew growth. Microorganisms thrive in a wet environment, and the increased presence is a telltale sign.
  • Air feels moist, clammy, and harder to breathe. There are also unpleasant, mustiness odors lingering in the air.
  • Your skin may feel sticky and muggy when you’re inside the home.
  • Condensation/ foggy windows. A clear sign as vaporized water will fog up the windows.

Conversely, if the humidity level is too low (below 30%), the heating system will struggle to keep warm as the temperature drops quickly. Your home will feel much colder than the temperature suggested. Below are a few clear signs of low indoor humidity:

  • Dry, flaky, and itchy skin.
  • Dry throat, nasal, and eyes.
  • Increase in static electricity.
  • Susceptibility to diseases with symptoms like cough, sinus, headache. Germs, bacteria, and viruses spread faster in dry air.
  • Unexplainable dry rot. You will notice cracks and chipped parts on wood furniture as moisture is pulled out.

How Humidity Affects Air Conditioning

Air conditioners cool homes by removing heat and excess moisture from the air. It reduces the indoor temperature to create a comfortable home even on the hottest day. When the home’s humidity level is exceedingly high, the air conditioner will have to keep running to compensate for the damp air. As a result, the AC will use more electricity due to the longer operating hours, and you will end up paying a higher utility bill. Worst still, if the BTU rating doesn’t have sufficient cooling capacity, it will struggle to cope with the extreme humidity and thus fail to cool the air effectively.

That said, you should buy the right size air conditioner for your home. A large and powerful air conditioner does not guarantee more effective cooling and better moisture removal. If your AC capacity is much higher than the room size, it will use more energy, yet your room humidity level will remain high. This is because large air conditioners with high BTU can cool down room temperature quickly before it had a chance to remove the moisture from the air.

How To Decrease Humidity?

Having proper humidity creates a comfortable environment, protects the longevity of your air conditioning, reduce fogging, and save money on energy bill as an air conditioner does not need to run as often. Most importantly, it is good for your health. To help you get started, here are ways you can reduce indoor humidity:

  • Get a dehumidifier – The best way to reduce moisture. A dehumidifier is a simple moisture removal appliance that will remove moisture and maintain your home humidity level based on the adjustment you made. The drained moisture will be collected in a reservoir or forced out via a hose. Pairs well with your air conditioning system.
  • Use a dryer or dry laundry outside – Wet clothes and towels can greatly contribute to the humidity level in the room. Place your dry rack outside or consider investing in a dryer.
  • Take a cool shower instead of hot – Every little bit helps. The lower temperature and less steam creation will reduce the addition of moisture back to the room.
  • Open window and door – When the AC is not running, you can improve airflow circulation and dampness by opening windows and doors. It is simple as that.
  • Fix leaky pipes – Leaking pipes, faucets, ducts, and congested gutters are one of the main contributors to a wet environment. Hire a plumber or fix it yourself whenever there are water stains on drywall, ceiling, and wall.
  • Turn on the fan – From exhaust, ventilation, wall, or ceiling fan, the breeze helps warm air evaporate, so you will feel cooler without the dampness and stuffiness feeling.
  • Continue using your air conditioner – It will replace the hot and humid air with cool, dry air. Just make sure to clean the air filter regularly to prevent airborne particles from damaging the evaporator and condenser coils.
  • Avoid indoor houseplants – While there are many health benefits to houseplants, it is better to move them to a non-humid area. It will reduce the moistness while also protecting the houseplants from getting mold-infested.
  • Baking soda, charcoal briquettes, and desiccant – Moisture absorbent elements that will still suck moisture out of the air. Nonetheless, it is a poorer substitute for a dehumidifier that you will have to replace regularly.

How Humidity Affects Heating

Heating Ventilation and Cooling (HVAC) systems help keep us warm and cozy, particularly during winter. When the home’s humidity level is too low, it causes the indoor temperature to drop swiftly as cold air is unable to hold much moisture as warm air. The furnace heater will struggle to pump out heat to keep us warm. The heating system will end up using more electricity due to the longer operating hours and will be reflected on your electrical bill. Maintaining an ideal humidity level will allow the heating systems to function correctly.

How To Increase Humidity?

To heal yourself from a dry throat, flaky skin, itchiness, and other irritating symptoms, you will need to increase the indoor humidity. To accomplish that, just do the complete opposite of our dehumidification recommendation as such:

  • Get a humidifier – Undoubtedly, the most effective method in adding back moisture to the air. Whether it is a warm-mist, cool-mist, or ultrasonic humidifier, it will work with HVAC systems to make your house feel warmer while saving money on the electric bill.
  • Leave the bathroom door open after a hot shower.
  • Closed windows and doors.
  • Get more houseplants.
  • Air-dry your dishes, clothes, and towels indoors.
  • Place dishes of water all around the house.

So What Is The Best Temperature And Humidity?

Ideally, the thermostat in a home should be set between 71-77 degrees Fahrenheit and a humidity level between 30-50% for optimal comfort. If the room temperature or humidity level is not at an ideal range, the home will feel much warmer or colder. As a result, our body will automatically regulate its tempeature through perspiration. Evaporated sweat will cool our skin, and the blood vessels will dilate, allowing heat to flow out of the body.

To measure the humidity level in your home, get a hygrometer or use the simple ice cube test. Add a few ice cubes into a glass filled with water and wait a couple of minutes. If there is no condensation outside the glass, the air is too dry. If there is, the humidity level is high.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.