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Does a Dehumidifier Cool a Room?

Last updated November 27, 2021

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Author
Author avatar Danny Ashton

Danny as been writing about air purifiers for 10+ years. He is a major fan of home technology, which makes him the perfect person to test and evaluate products for HouseFresh

One person’s warm is another person’s not warm enough. 

When talking about the ‘feel’ of a temperature it’s about how someone perceives it, not the number on a thermometer. With that in mind, when someone asks,  “does a dehumidifier cool a room?” the answer needs to cover both the ‘feel’ and the temp.

The goal of a dehumidifier is to remove humidity in a room not to cool the room which is best left to air conditioner units whose single aim is temperature reduction.

Does a Dehumidifier Cool a Room?

The answer to this question is no, it can’t. Like so many questions involving physics and chemistry, the answer is simple but understanding the answer? Not so much.

A dehumidifier actually heats a room, at least by a little, and that warmth increase closer to the device itself. 

To cool a room, the dehumidifier would need to be taking energy out of the room. Temperature, after all, is a measurement of the energy in the air. 

But why do people think that they cool the air?

In a peer-reviewed paper, they found that many people found that a reduction in humidity led to a more comfortable environment.

The reason is that the reduction in humidity will feel cooler even though the temperature has stayed the same.

But this is an inefficient way to cool a room – far better to use an AC in combination once you have reduced the current room’s humidity.

Dehumidifier Operation and Methods

A dehumidifier strips the moisture out of the air. It does this either through a condensation coil or a desiccant material. Both methods require a pump to pull in air.

In a condensation unit, the air flows through a coil that is cooled via a compressor or some type of refrigerant. This chills the air and forces the water vapor in the air to condense into droplets. The air is then pushed back out into the room. 

A desiccant unit sends the air through a chamber composed of one or more layers of material that absorbs moisture. 

Why does a dehumidifier make it feel like it can cool a room?

So, if the room isn’t losing energy, how does it feel cooler? 

To grasp the answer to this refined question you need to know a few things about humidity and how your body regulates its temperature internally. 

Humidity

How much water vapor the air can contain without spilling it is referred to as humidity. The amount of vapor depends on several factors including the temperature of the air itself. Higher temperature air can hold more vapor than lower-temperature air.

This is how a condensation unit does what it does, it chills the air in the coil, squeezing the water vapor into liquid water. 

Relative humidity indicates how much vapor the air currently holds on a scale of 0 to 100. You can explore how humidity works at home with this list of simple experiments

When you hear a meteorologist talking about high and low-pressure systems, they are talking about levels of energy, when high pressure meets low pressure, the chance of rain increases. 

The humidity of air affects living things in different ways. For some creatures, like plants and insects, humidity is great. They drink through their skin so they need the liquid to accelerate their growth and offer opportunities for repopulating and expansion. 

In a commercial space, machinery needs to operate within stable conditions to avoid excess wear. Commercial dehumidifiers push more air to rapidly dry a larger space. 

For mammals, excess humidity sticks to the skin and reduces our ability to cool effectively. 

Perspiration

As mammals, humans maintain an internal temperature through metabolic processes. The body is capable of holding heat in and dispelling heat to maintain a precious, limited window of internal temperature.

Once the external temp hits 98.6 F (37 C), the body begins to perspire.  

Perspiration is a form of evaporative cooling. Your body releases water droplets through the pores (sweat) and those droplets evaporate. Perspiration cools in two ways, first, it shields the body from absorbing more heat, the droplets take the heat to raise their energy levels and become vapor.

Second, the evaporation takes heat from the body as it dissipates. The sweat droplets heat from both sides.

Now, because the air already contains an amount of water vapor (humidity), the speed at which droplets evaporate changes. If the humidity is too high, there is no room for further vapor at that temperature, leaving you covered in sweat but not cooling down at the same pace.

Drier air means more room for water vapor means more rapid cooling. 

Energy States

Energy tries to reach equilibrium. This is another component of the Second Law of Thermodynamics. All energy in the universe equals zero and any given system is trying to balance as well.

A room is a system. Your body is a system. 

When the air is dry enough, your skin loses some water to the friction of air against it. This is why you feel ‘cool’ in a drier room than a more humid room at the same temperature.

To maintain a constant level of humidity (and temperature) in a room you want to purchase a whole-house dehumidifier capable of working the volume of air properly. Too small and it runs constantly, generating excess heat and noise.