Last updated: August 9, 2021

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On hot summer days, rooms get warm quickly and are difficult to cool down. Room air conditioners can help cool down rooms to make the summer as comfortable as possible, no matter what the living situation. In our room air conditioner test 2021 we show you different types of room air conditioners and explain which criteria you can use to find a suitable device for your home.


  • Room air conditioners are useful and help to cool down on hot summer days. Mobile air conditioners are practical and can be placed in any room and fixed air conditioners are great in larger rooms.
  • When buying a room air conditioner, you should make sure that they have a good efficiency rating so that you can save as much electricity as possible and thus save money on your electricity in the end.
  • Basically, you should also know how big the room you are using is in order to calculate the optimal cooling capacity for your room so that the room can be optimally cooled.

The Best Room Air Conditioner: Our Choices

Room air conditioners: buying and evaluation criteria

It is important to know how to recognise a good room air conditioner so that you can find the best device for you and adapt it to your needs and environment.

In the following, you will find important buying criteria explained and listed so that you can take them into account when making a purchase.


The size is important and can vary depending on your ideas and possibilities. If there is little space in the flat, mobile air conditioners are suitable because they are usually small and can be moved into any room. This also makes them flexible to use and you can find them in different shapes.

In small flats, it is advisable to make sure that the room air conditioner does not have a drain hose.

Most room cooling units are not very large, but they cannot always be placed in a practical way due to the drain hoses that go with them, because they have to be mounted either on walls or windows so that the drain hose can convey the air from the unit outside.

Cooling capacity

The cooling capacity of a room air conditioner is of great importance because it is decisive for the purchase. The cooling capacity is measured or displayed once using the wattage and the British Thermal Unit (BTU).The BTU can be easily converted into watts.

The room size is decisive for the optimal cooling capacity.

For small rooms of up to 20 square metres, an air conditioner with an output of up to 2,000 watts is sufficient. For rooms of up to 30 square metres, the cooling capacity should be 2,400 to 3,600 watts.

Basically, you can estimate that you need about 60 to 100 watts of cooling capacity per square metre, so you can calculate it for your room size.

Energy efficiency

Room air conditioners are electricity guzzlers, so you should pay attention to good energy efficiency in order to use electricity sparingly and so that the electricity costs are not too expensive. Below we explain all the energy classes.

  • Efficiency class A+++: is the best energy efficiency a room air conditioner can have. Permanently installed units can also have efficiency classes from A++ to A+++ and are usually more energy efficient than mobile units. It saves up to 30% more electricity up to class A++.
  • Efficiency class A++: can save up to 10% more electricity than class A+ and is often found in permanently installed split air conditioners.
  • Efficiency class A+: Mobile room air conditioners can have this as a maximum and it can also save up to 10% more electricity than the previous class A.
  • Efficiency classA: is most commonly found in mobile room air conditioners and can be up to 10% more energy efficient than class B.
  • Efficiency class B: Normal room air conditioners are only allowed from efficiency class B because otherwise they consume too much electricity. Compared to class A+++, a room air conditioner in class B can consume 40% more electricity. Therefore, you should better invest in at least an energy efficiency class A.

It is usually a good idea to buy room air conditioners with the highest efficiency class in order to really be as energy-efficient as possible. Units with efficiency class B are not worthwhile because of their high electricity costs, although they are usually much cheaper than higher efficiency classes.


For most households, it is important to find a quiet room air conditioner because a constant noise scene can be very nerve-wracking in the long run. You should pay attention to how many decibels the unit has. Generally, units with a value of 50 to 65 decibels are the most popular and there are only a few quieter models.

Generally, most room air conditioners are between 50 to 65 decibels, which is comfortable and quiet. If the noise level is above 65 decibels, it can be uncomfortable after a while and too loud.

Room air conditioners: Frequently asked questions and answers

A room air conditioner is an investment for every household, so you should be well informed before buying one. We answer basic questions about room air conditioners so that you are well prepared and have the background knowledge for the purchase.

Who is a room air conditioner suitable for?

A room air conditioner is great for hot days for the perfect cooling. Basically, they are suitable for any room size and are usually easy to control.


A room air conditioner is used to lower the room temperature as well as to filter the room air. (Image source: Mustafa shehadeh / Pixabay )

It does not always have to be a classic permanently installed air conditioner, but can be placed anywhere through different types such as the popular mobile room air conditioner.

So a room air conditioner can fit into any room and provide cooling for everyone. So they can be placed anywhere in the office, bedroom or many other rooms, making it easy to endure the hot summer days.

What types of room air conditioners are there?

There are many different types of room air conditioners and depending on the one, some are more suitable in your home than others. Below we list the different types and give you some advantages and disadvantages.
Type Advantages Disadvantages
Mobile room air conditioner Flexible and can be placed anywhere Usually not enough cooling and high energy consumption
Wall and ceiling room air conditioner Can be placed well on the wall But is not as flexible as a mobile unit
Split room air conditioner Is a permanently installed unit, which is the most energy efficient But it is difficult to install and can only provide cooling in one room

How much does a room air conditioner cost?

For small rooms or if you want to be able to move the unit flexibly, a mobile air conditioner is an excellent choice for your home. Mobile units are also suitable for small flats because they are usually small and compact and easy to transport.

The price range for a room air conditioner can vary from inexpensive models to very expensive models. Here, the price range differs depending on the type of room air conditioner. Below you will find a list of the different types of products with their respective price ranges.

Product type price range
Mobile room air conditioner 40 to 300 euros
Wall room air conditioner 200 to 800 euros
Ceiling room air conditioner 200 to 800 euros
Stand room air conditioner 100 to 500 euros

In most cases, cheaper models are characterised by a very energy-consuming electricity class, which means that you often don't save any money and should go for energy class A instead.

In general, you can find good air conditioners at a medium price. Of course, you should always pay attention to the various criteria that are important for a purchase.

How do I use a room air conditioner?

A room air conditioner is easy to use and can usually be easily controlled by a remote control. Of course, you should be careful not to use the air conditioner wastefully and only when necessary, because this can result in high electricity costs.


In addition, a higher ventilation or air supply setting can often save more electricity than a low setting. (Image source: Zulki Jrzt /Unsplash)

It is advisable not to switch on the room air conditioner when the room is already overfilled with heat, but it is more energy efficient to switch on the unit beforehand. This allows the unit to stabilise the room temperature better. In addition, it can be more efficient to switch on the highest air supply level, because this reduces electricity consumption.

What alternatives are there to a room air conditioner?

A room air conditioner can be very expensive and there are some alternatives you can look at if you are looking for something cheaper. Below we explain the alternatives so you know what they are and how they work.
Alternatives Advantages Disadvantages
Fan The most popular alternative to a room air conditioner, flexible and easy to set up Just an extra air supply and no cooling air as with an air conditioner and loud
Natural air conditioner Easily self-adjustable with cloths dipped in water hung over an open window and this can lower the room temperature Can be annoying to repeat this process and warm air can easily flow into the room through the open window.
Humidifiers Can fill the room with more humidity, thereby changing the dry climate in the rooms The humidifier does not make it cooler, but somewhat more pleasant.
Sun protection film They are attached to windows and can lower the room temperature from 3 to 5°C. They are cheap and effective the darkened windows can be disturbing for some.

The alternatives are usually very cheap and can be easily set up to try. They may not cool the room as effectively as a room air conditioner, but they can be a good short-term solution and are easy to set up.

How do I clean a room air conditioner?

There are different ways to clean a room air conditioner. It depends on whether it is a mobile or a permanently installed room air conditioner.

With mobile air conditioners, the filter can be easily cleaned and changed.

With permanently installed room air conditioners, cleaning is somewhat different. First of all, the outdoor and indoor unit should be cleaned, because germs or bacteria can form in both. On the outside, it is best to remove the grille from the air filter and clean it.

For the indoor unit, you can simply vacuum up the dirt with a hoover. If more dirt has accumulated, you can remove the filter and rinse it with soap and water. The filter should also be replaced once a year. With mobile air conditioners, you can also easily remove the filter and clean it with soap and water. In addition, most mobile air conditioners have a water tank, which should also be cleaned.


Room air conditioners can be very useful for cooling a room and often have many additional functions, such as a dehumidifier function.

They can be used in any size of room, and their compact form makes them variable and flexible. Therefore, room air conditioners are suitable in every household to enjoy the perfect cooling in summer.

Image source: Davydov / 123rf

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