What Should Humidity Be in a House with Air Conditioning? 30-50% Always!

The ideal indoor humidity with AC running should be between 30 and 50 percent.

Well, with or without air conditioning, the recommended indoor humidity level is between 30 and 50%. Regardless of the season, your indoor humidity should always be within this range.

Perhaps you can even let it go to 55% or even 60%, which experts consider okay. However, when you have 70 percent humidity, it is too high!

Back to our topic of the day, you should know that there is a relationship between humidity and temperature.

When air has more moisture content, it feels hotter than when it is dry. It gets so serious that it triggers the body to start sweating to “cool” down.

It can even lead to overheating. You can read our article on the effects of high humidity on health. It sheds more light on how the body behaves when the humidity is too high.

How humidity affects air conditioning

Indoor Humidity With AC Running

The air feels hotter in high humidity. That’s a fact.

To know what the humidity level should be in a room when there is air conditioning, you need to understand how heat and humidity are related.

An air conditioner cools the air by lowering the temperature. It also lowers the humidity by a very small margin.

Actually, in a room with high humidity, you cannot feel any difference when you switch on the air conditioner.

Absolute vs relative humidity

There are two different ways of measuring humidity. First, you can check it as absolute humidity, which is the amount of moisture in the air at any temperature. This is the real humidity.

Relative humidity, on the other hand, is the amount of water vapor in the air at a given time, concerning the actual amount of water that the air could hold at saturation level.

This is why it is expressed as a percentage. So, 50 percent relative humidity means the water vapor in the air is at 50 percent of the total amount of water that the air can hold at that temperature.

To avoid any confusion, we use relative humidity for our indoor air. Just keep it between 35 and 55 percent.

Too high humidity can cause the air conditioner to overwork

When the indoor humidity is too high, you will feel hotter. Thus, you will want to lower the thermostat in your air conditioner in an attempt to get it to lower the temperature further.

What you don’t know is that the high moisture content in the air is making you feel hotter.

While the temperature is low enough for the air conditioner not to turn on, you are tempted to lower the thermostat of the air conditioner.

Your air conditioner works extra hard to give you a certain level of comfort. But it is not supposed to do that. High-humidity cooling does not work very well, especially in high summer temperatures.

Overall, forcing your air conditioner to work too hard in high humidity shortens its life span a great deal. To avoid this, just buy a dehumidifier and an air conditioner.

The air conditioner also uses electricity, so it can rack up your bills if you run it too often.

How does your air conditioning work?

The air conditioner is designed to sense when the indoor temperature is too high, and then it automatically switches on to cool the air.

To do this, it has a thermostat. When it starts working to cool the indoor air, it will remove just a small amount of moisture from your indoor air. This will not make a difference in your indoor humidity.

Do not rely on your air conditioner’s humidity setting because it will not help matters at all. However, it is quite alright to run a dehumidifier and an air conditioner simultaneously in the same room.

A dehumidifier blows hot air into the room, but this is not enough to cause the air conditioner to turn on.

Thus, when you run the two appliances together, they will not interfere with each other.

When to use air conditioner and dehumidifier simultaneously

When to use air conditioner and dehumidifier simultaneously

This is in summer. In hot summer weather, the air feels more sticky, and the high temperature holds more moisture.

If you run the dehumidifier alone, you will still leave the air feeling hot because a dehumidifier blows hot air. The summer temperature is too high! A dehumidifier only blows cold air when it is faulty.

If you run the AC alone, you will leave the room feeling more humid. No matter how much you overwork the air conditioning, it will remove a very small amount of moisture from your air.

In the winter, the air feels dryer. So, you will probably need a humidifier in winter. Thus, you can see how moisture control can leave your home feeling cooler in summer and warmer in winter.

What should humidity be in the house with air conditioning: FAQ

Temperature and humidity are related. An air conditioner controls the temperature of a room, while a dehumidifier controls the humidity level.

Image of air conditioning and humidity

For many people, though, the relationship between temperature and humidity is still too complex. Here are frequently asked questions to help you understand it better:

How does air conditioning alter the relative humidity of a room?

Running the air conditioner alone when the humidity is high will only have a small effect. The AC can only lower the indoor humidity by 10 percent. Thus, you need to run the air conditioner and the dehumidifier together.

Do air conditioners dehumidify the air?

A large air conditioner can dehumidify a small room faster. A small AC will work extra hard, and it will just lower the water vapor content in a large room by about 10 percent or less.

What is normal humidity in an air-conditioned house?

The best humidity level to set for your home is between 30 and 55 percent, irrespective of whether you are using an air conditioner. If the humidity level is higher than 60 percent, it will cause the growth of mold.

How much does humidity affect heat?

When the humidity is too high, the room will feel hotter because high water vapor retains heat. If you do not lower the humidity, you will keep running the air conditioner unnecessarily, sometimes even lowering the thermostat.

Why is my air conditioner not lowering the humidity in my home?

The reason you cannot notice any difference in the humidity level when you run your AC is because the humidity level is too high. So, the 10 percent difference that the air conditioner can make in your humidity level is too low to notice.

Also, check the evaporator coils, because when they are dirty, they prevent the AC from cooling the air in your home.

Does the air conditioner increase humidity?

No. If anything, when you lower the temperature of the air in your rooms, you are going to lower the humidity by a small margin. So, an AC lowers the humidity, not increases it.

Final thoughts on the best humidity level in a house with AC

Air conditioning and humidity go hand in hand. More heat can cause more humidity. Thus, cooling your indoor air can lower the humidity level, but by a small margin. The secret, therefore, is to buy a dehumidifier to help your AC along in the summer.

Does your HVAC have a dehumidifier? That is the only way it will lower humidity properly.

You can have a whole house dehumidifier installed by a professional HVAC technician in your home.

You can use a hygrometer to check the effect of air conditioning on humidity. If humidity goes up when the AC is on, is faulty, or it is too small for the room.