How Well do Ventless Air Conditioners Work?

This article sets out to answer the question that asks, "How well do ventless air conditioners work?" It also explains what these cooling appliances are and how they work.

With ever rising energy prices to contend with, finding an economical cooling solution is becoming ever more important.

Air conditioners are the most common form of cooling devices that absorb heat and humidity from the air and then move it outside in order to cool the air inside a home or other building.

However, air conditioning equipment uses a lot of electricity when operating and this is making this form of cooling ever more expensive for many families, especially those on limited budgets.ventless air conditioner

Let's first look at why air conditioning is so expensive to run, after which we'll look at the more economical alternative.

Why Air Conditioning is Expensive to Run

Air conditioning creates cool air indoors by taking room temperature air and forcing it through a chilled lattice of pipes which condense moisture from that air and remove its heat.

This is made possible by a mechanical compressor that compresses a refrigerant gas inside the circuit of pipes, causing it to drop in temperature and chill the pipes it flows through. This process uses a certain amount of electricity to run the compressor.

At the other end, a condenser removes moisture from the chilled air, drying it before returning it to the room being cooled. The unwanted hot, moist air that is the by-product of this process is exhausted to the outside through ducts to dissipate harmlessly into the outside atmosphere.

The complete process can use upwards of 2 kilowatt hours of electricity and when left running for most of the day and night during summer. This adds up to a lot of energy usage over time, equating to a hefty electricity bill finding its way into the mailbox.


If you don't have tubing to transport coolant through your wall, the conditioner will need to be mounted inside and outside like a window unit.

You also need to vent hot air from the window using an air hose and a loud fan. There are many ways to make a room feel more comfortable, even if your definition isn't too strict.

Evaporative Coolers

Evaporative coolers are the most common, also known as "ventless air conditioners."

You can call them "swamp cooler" or "evaporative air cooler", but they're essentially somewhere between a humidifier and a misting room fan.

How Do Evaporative Air Coolers Work?

Evaporating water cools air just like melting ice cools your food in coolers: By absorbing more energy as it changes from one phase to the next.

Cooling with evaporation is like throwing a party. Liquid is composed of low-energy molecules sitting in one corner.

Evaporated water, on the other hand, is made up of hyperactive high-energy molecules that dance all around the room. Water must absorb heat energy in order to change from being relaxed to hyperactive.

Dry, hot conditions can cause water to evaporate quickly. A sponge-like filter is used to collect the water and then push the air through it using a fan to speed up the process.

Evaporative coolers will continue to function until the air becomes too moist to absorb more of the vapor. The best evaporative cooling systems work when the cool air is let out and warm dry air comes in through a door or window to replace it.

Where Are Evaporative Coolers Most Effective?

The more dry your air, the more efficient evaporative cooling is. The higher the humidity, the less effective are these coolers.

Here are three conditions where evaporative cooling can work best:

  1. Ideal areas with low daytime humidity of less than 45% and high maximum temperatures below 90°F
  2. The ideal humidity is the same in all regions, but the temperatures are higher than 100°F
  3. These are the less-suited areas with high temperatures of up to 100°F and summertime peak humidity of between 45%-55%

It is difficult to tell the difference between cooling in ideal zones and higher humidity areas. An example set shows that an evaporative cooling system can cool extra-dry air by 29° in 90°F weather at 15% relative humidity.

Where Are Evaporative Coolers Least Effective?

The areas where evaporative cool works the best are not covered by a large portion of the United States' population.

Evaporative cooling is an affordable way to cool down rooms if you live in the Southwest, Washington or inland of Eastern Seaboard.

Even though evaporative cooling may be effective in the desert, it is less likely to work in extreme heat.

Portable Air Conditioners vs. Ventless Air Coolers

The choice between these two systems is based on climate. Ventless air conditioners work better in dry climates where evaporative cooling is not an option.

They also humidify the air while they cool it. However, the evaporative cool won't work in humid regions like the Deep South.

Dry Conditions

You won't feel uncomfortable if the air is dry. An evaporative cooler can provide humidity to increase the humidity to your skin.

Desert conditions can be made tolerable by using a combination of shade, cool water from an insulation bottle, and an electronic cooler.

An air conditioner will dry your air as it cools it. Even though portable air conditioners can be used to cool air, they are not able to cool down the room below 75°F during the summer heat wave.

For those who require substantial cooling, central AC or window AC systems work much better.

Humid Conditions

Evaporative systems will not work in humid conditions greater than 60% relative humidity. Evaporative systems are not able to function if there is humidity outside.

Portable air conditioners work in the same way as stand-alone dehumidifiers but instead of leaking heat back into your room, they let all heat it has absorbed out through a window.

Portable air conditioners also use the water they capture to cool their components. This increases efficiency and eliminates the need to dump out a tank each hour.


Ventless air conditioners work very well in dry conditions when the level of moisture in the air (humidity) is below around 45%.

However, at humidity levels above 50% and rising, the effectiveness of unvented evaporative coolers is greatly reduced, while at saturation point (100% humidity) they cease to produce any cold air at all.

This is in contrast to true air conditioners, that act as dehumidifiers when cooling the air and can still create chilled air despite the humidity level. Where you live has a huge bearing on which form of cooling is best and most effective for you during summer.