What Should Humidity be in the House with Air Conditioning?

Households that use an air conditioner typically have less than 40% relative indoor humidity levels.

On an extremely low humid day, you might need to turn on your humidifier just to keep things comfortable indoors.

The ideal indoor humidity level should be around 30-50 percent with air conditioning, although depending on your preferences you may like it more or less humid.

Whether you need to decrease humidity or you have too much humidity, we are here to help.

What is the ideal indoor humidity level?

The general consensus seems to be somewhere between 30-50 percent relative humidity.

Some may like it more humid or less, depending on preference.

How to know if the humidity level is too high in your home?

1. Mold growth

Mold grows when moisture collects on surfaces, especially windowsills and walls where leaks are common.

Mold can spread quickly in homes that have poor ventilation or suffer from repeated water damage.

2. Musty odors

Another sign of too much moisture indoors is a musty odor emanating from condensation inside light fixtures, fireplaces, old closets, or other enclosed areas within your home.

You may even be in the bathroom when you smell a weird musty smell. Don’t ignore it, The longer it stays, the worse it can get.

To protect you and your family, you will need to figure out where the source is and try lowering the humidity in that room.

If your air conditioner smells like vinegar, that’s an entirely different problem in itself.

3. Collapsing stairwells or unstable furniture

Certain molds are especially bad for indoor air quality and may lead to asthma attacks or allergic reactions.

High humidity can also cause wood rot in poorly-ventilated areas of the home.

Stairwells are classic examples of where rotting can occur if moisture isn’t controlled properly. Stairs that feel spongy when you step on them may be signs of mold growth under the surface.

High indoor humidity can cause wood furniture to swell, which may result in the gaps between floorboards being completely stuffed with sawdust.

If you have a home humidifier it is ideal to keep the humidity level under 50% at all times to avoid any damage from overhumidification.

4. Damp effect on paint

Damp conditions, as well as warm weather, can also cause paint to peel quickly at the edges of walls or ceilings.

If you notice this happening with your home’s interior paint jobs, look for moisture intrusion points in those areas where the paint is failing..

Causes of High Humidity with Air Conditioning

1. Poor ventilation

Closing windows and doors will lead to inadequate ventilation, contributing to poor humidity levels.

Make sure to keep all vents open, too, if you have a central air conditioning system.

2. Outdoor vs Indoor air temperature

When the temperature is hotter outside than it is inside when the air conditioner is on, this can lead to high humidity levels. If you notice excessive humidity on days like this, run the fan a little longer and provide sources of adequate ventilation.

Your AC may not run properly either if it’s too cold outside.

If it’s summer, you may try a few different methods to lower the humidity.

3. Poorly perforated ceiling insulation

If you have poor insulation in your ceiling, this means it is blocking conditioned indoor air from being able to freely escape to the living area above.

This is one of the drawbacks of having a two-story home. However, if you have an experienced HVAC professional, they can fix the issue so you can maintain ideal indoor humidity levels.

4. Poor installation of central air conditioning

When central air conditioners are not installed properly, it leads to insufficient airflow to and from the air-conditioned living space.

5. Excess condensation

When humidity is present to a degree that it can be felt or even seen in the form of condensation on surfaces such as windows and mirrors, this is a good indicator that there may be a serious underlying issue going on.

Most homeowners often ignore these signs. Even consistent foggy windows are a sign you need to control humidity in the room.

You can also find our in-depth guide on why your house is humid even with your air conditioning working full capacity.

How to Reduce Humidity in Air-Conditioned Room

1. Use a dehumidifier

Room dehumidifiers are now available even in small sizes, which can help reduce humidity up to 80% of the air you breathe in. Place this unit near where you sleep.

A whole-house dehumidifier can work to control moisture as well if you would prefer one of those over a portable room humidifier.

High humidity is a great reason to use a dehumidifier.

2. Check your air conditioner air filter

Keep the air conditioner filter clean.

Dirty filters will have a hard time letting air pass through, causing more humidity and less cooling effect.

Clean or replace the filter once every few months to keep it running optimally.

Pick up the best AC filter for allergies if you find you’re having difficulty inside of your home.

3. Use exhaust fans

Use exhaust fans whenever cooking or running the laundry machine.

This will suck up any excess hot air from these appliances (especially when drying clothes), making them cool down faster and avoid adding excess heat into the room while you wait for them to finish their cycle.

4. Proper ventilation

Make sure you are using proper ventilation with your home’s HVAC system.

If you are unsure how to make sure how venting works with HVAC systems, a professional can help you.

If you are having some damp or musty smell, definitely have a HVAC professional see if they can guide you to some venting techniques.

You will also want to make sure that if you have a basement or crawlspace, you must have vent fans or something similar to move around the air. If not, you are going to have major issues with humidity levels.

5. Natural Options

Don’t forget about natural options when you are trying to control humidity levels.

You can place plants around your home, open a window for a certain amount of time each day, take shorter and colder showers, and try line drying your clothes instead.

Do ACs still work well when it’s humid outside?

The inside the inside of your house should be fairly dry. There are two main reasons why you want to have a dry air conditioner environment: First, humidity can condense on cold coils and drip into your room or onto furniture, etc.

Humid weather will decrease your AC’s cooling capacity drastically. If the relative humidity is very high – say 90% – then there won’t be much difference between indoor temperature and outdoor temperature.

Moisture will diffuse back out through your vents before it has time to cool off.

If you have a hygrometer – they’re cheap- you can measure how much moisture there is in the air inside your room after running the AC for some time.

Even if it’s not humid or cold outside, a lot of indoor spaces will accumulate a lot of water vapor due to cooking, showers, and bedsores (people perspiring at night).

Your AC will not be able to remove effectively this “extra” humidity from the air.

If you keep finding that the absolute humidity level is high even though the temperature seems cool enough then most likely you need a dehumidifier too.

Air conditioners can remove humidity as well, so keep that in mind.

Benefits of keeping your house at the proper humidity level

In addition to making you feel comfortable and helping you breathe easier; humidity helps protect your sensitive household items from damage caused by dryness.

Humidity levels affect a number of different aspects of health and well-being.

Other benefits:

  • Helps eliminate static electricity
  • Keeps wood floors and furniture in good condition
  • Eliminates parched skin during dryer winter months
  • Prevents any wooden belongings from cracking

Final Thoughts

Maintaining ideal humidity in your home is vital to prevent any family sickness and damage to your home.

Be sure to take care of any musty smells you notice, or other signs of high humidity.

A portable room humidifier or whole house humidifier can do your home well for this particular issue.

If you’re not sure how to fix the issue, don’t hesitate to call an HVAC professional.

With the proper training and knowledge, they can either increase humidity or remove humidity in your home so you can achieve proper humidity levels.

About Heather Burdo

With almost a decade of experience with digital marketing, Heather Burdo has gained diverse experience across a multitude of industries. You can reach her at [email protected]

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