Last updated: 16/10/2022

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Do you love to get through the summer nights heat-free? Doesn’t morning ventilation help you to keep your home cool? According to studies, we spend an average of 90 percent of our time indoors. Room temperature and humidity are an essential part of our well-being. Now there is an end to room temperatures that are too cold or too warm in your own four walls. Heat and excessive humidity are a thing of the past. The air conditioner helps you to set your optimal air temperature and optimise your well-being.

Welcome to our air conditioner test 2023. We want to help you find the best air conditioner for you. We have compared different air conditioners and present our results in this article. This will give you an overview of the most important information you need to be aware of when buying an air conditioner.


  • In addition to the cooling effect, modern air conditioners have the function of regulating the air humidity. This improves the feeling of well-being in the cooled room and the respiratory tract is not stressed. Note: The cooling effect is only guaranteed if the air conditioner is adapted to the room size.
  • Regular maintenance of an air-conditioning system prolongs the service life of the equipment and ensures maximum energy efficiency. Several experts recommend that air conditioners be serviced annually by a specialist.
  • The optimal combination of the right energy efficiency class and low consumption can reduce costs and thus counteract a cost trap. Compared to a split air conditioner, the inverter technology has a lower energy consumption because the cooling capacity can be adapted to the individual wishes and the environment.

The Best Air Conditioning: Our Picks

Buying and evaluation criteria for air conditioners

Buying an air conditioner is also an investment in the future. That’s why you should think in advance about which aspects your air conditioner must fulfil.

The criteria that help you compare air conditioners with each other include:

Cooling capacity

The right cooling capacity is the first prerequisite for determining the right air conditioner to meet your needs and wishes. It indicates how much heat energy is converted per unit of time.

Two units of measurement are important for this: BTU and Watt. In the field of air conditioning, BTU stands for cooling capacity per hour. Watt denotes a certain amount of energy per unit of time. How much cooling capacity you need and what you have to consider can be easily calculated and checked with the following rule of thumb:

  • The rule of thumb for calculating the air-conditioning output per room: room area in square metres times 60-100 watts. For example, for a 30 square metre room you need an approximate cooling capacity between 1800-3000 watts.
  • External influences: Add about 150 watts per person in the room. For perfect room cooling, you should also include the individual wattage consumption of the individual electronic devices in your calculation.
  • Differences in size: The required cooling capacity varies depending on the size of the room. In general, the larger the living space, the greater the energy required per unit of time.


1,000 BTU/h correspond to around 293 watts. Accordingly, the BTU/h value is approximately three times the watt unit of measurement.

Size and weight

An important purchase criterion is the weight and size of the air conditioner. Depending on the intended use, these factors should be taken into account in your planning.

Stand-alone units should be compact and light. This allows you to adapt the mobile air conditioner to your individual room. Window air conditioners, on the other hand, must be adapted to the desired dimensions of your window or wall height.

Electricity costs

This section gives you an overview of the general costs involved in buying an air conditioner. The costs listed are non-binding and vary depending on the purchase and operating costs of the respective supplier.

Product types Electricity costs Purchase and installation costs
Central air-conditioning system 120 to180 Euro per year from 7500 Euro
Decentralised air-conditioning system 150 euros per year from 2200 euros
Mobile air conditioning 24 cents per hour from 100 Euro
Split air conditioner 20 cents per hour from 2500 euros
Window unit 18 cents per hour from 400 euros

Compared to other product types, the mobile air conditioner is the cheapest option. It is available in online shops and specialist shops from a purchase value of 100 euros. Depending on the cooling capacity, functions and finishes of the air conditioners, the price may increase.

With a price range of 100- 1100 euros, the mobile air conditioner is not a long-term solution for cooling a large area, as a lot of heat energy enters the room through open windows. The mobile air conditioner must therefore be able to cool twice the amount of heat in a short time.

In the long term, the split air conditioner is an inexpensive option. The electricity costs are relatively low and it is possible to cool several rooms at the same time.

Functions of an air conditioner

The air conditioner has several functions that you can use. Depending on the model, different functions can be found. Basically, every air conditioner must have a cooling function, otherwise it cannot be called an air conditioner.

The more compact the air conditioner, the fewer functions it can offer.

Most air conditioners have these three functions:

  1. Cooling or heating the air temperature
  2. Filtering individual air particles to ensure air purity
  3. Lowering or increasing the humidity of the air

Decision: What types of air conditioners are there and which one is right for you?

Air conditioners come in many different types. Basically, they are divided into central and decentralised air conditioners. A more precise subdivision is made into the different designs:

In this section, we have compared the respective types and examined them in more detail. It will help you to find the right air conditioner.

Central air conditioner

Central air conditioner

The central air conditioning system is permanently installed at a fixed point in the building. The respective air handling functions are combined in a central supply/exhaust air unit. Ventilation ducts connect the individual rooms with each other. They provide the necessary heat exchange. The treated and cooled air is supplied to all rooms via the air duct.

Central air-conditioning systems have very high initial costs. The installation of central air-conditioning systems involves a great deal of effort. They are always included in the construction process of a building, as retrofitting is often not feasible. Retrofitting requires cost-intensive conversion measures.

Nevertheless, central air conditioning offers many advantages. There is no noise generation, as the air-conditioning system is not installed directly in the respective rooms. System components, insulation material and sound-proofing caps reduce noise pollution. The individual rooms can be regulated individually and thus operate energy-efficiently.

  • No noise pollution
  • Individual air regulation
  • Energy-efficient
  • High purchase costs
  • Intensive maintenance costs
  • Retrofitting poses problems
Decentralised air conditioning

Decentralised air conditioning

Decentralised air conditioners are installed directly in the respective room. It usually consists of an outdoor and an indoor unit. This has the advantage that retrofitting can be carried out without any problems. The operating costs including installation are very low compared to a central air conditioning system. The possible mobility of the air-conditioning system supports individually usable cooling.

Nevertheless, some compromises have to be made. Due to the direct installation in the room, there is a lot of noise and the air quality is lower.

  • Low installation costs
  • Low operating costs
  • Retrofitting possible
  • High noise level
  • Poor air quality
  • Intensive cleaning required
Monobloc air conditioner

Monobloc air conditioner

Monobloc air conditioners consist of only one module. They are easy to transport and flexible to use. After purchase, they can be used directly, as the air conditioner does not need to be assembled.

We distinguish between monobloc air conditioners with a hose and monobloc air conditioners without a hose. The air conditioners that have a hose transport the produced exhaust air directly outside, whereas the other model blows the exhaust air directly into the room.

Monobloc air conditioners with a hose have to additionally cool the produced exhaust air. This is not energy efficient. Another negative aspect of monobloc air conditioners is the limited cooling capacity and the noise level.

  • Low mobility
  • Relatively low initial costs
  • No assembly necessary
  • Not energy efficient
  • Limited cooling capacity
  • High operating costs
Split air conditioner

Split air conditioner

Split air conditioners are decentralised air conditioning units that consist of two components. They have an outdoor and indoor unit. The outdoor unit discharges the warm air, whereas the indoor unit cools the room.

Construction measures must be agreed with the landlord or the authorities
  • The outdoor unit: It has a high noise level, which does not reach the inside due to the external installation. The indoor and outdoor units are connected by a refrigerant line.Therefore, major construction work is often required to ensure proper installation of the air conditioner.
  • The construction measures: They are associated with high costs and interfere with the appearance of the exterior facade.
    Nevertheless, split air conditioners are a cost-effective option because they cool energy-efficiently and have a higher cooling capacity.
  • Strong cooling capacity
  • Energy-saving
  • Low electricity costs
  • Construction measures necessary
  • High installation costs
  • Approval by landlord necessary
Inverter air conditioner

Inverter air conditioner

The On/Off system allows the cooling temperature of the air conditioner to be adjusted to the temperature differences between the set temperature and the room air temperature

In contrast to classic On/Off systems, an inverter air conditioner has an automatic compressor speed control. The compressor of a classic air conditioner rotates at a constant speed. This means that the compressor rotates at the same speed all the time until the desired temperature is reached. After that, the system switches off.

If the temperature rises again and exceeds the setpoint, the system switches on again and cools the room air down again. The inverter technology ensures efficient and energy-saving cooling by varying the rotation speed.

Nevertheless, they are cost-intensive to purchase. If you want to cool several rooms at the same time, the total cost of an inverter air conditioner can increase dramatically.

  • Energy efficient
  • Low running costs
  • Good cooling performance
  • High purchase costs
  • Construction work necessary
  • Landlord”s approval required

Guide: Frequently asked questions about air conditioners answered in detail

There are high costs associated with buying an air conditioner. An air conditioner is a big investment in the future. It is often a permanent part of your furniture for several years, so it is important to inform yourself in advance with questions and tricks about air conditioners.

In this section, we answer the most important questions you should ask yourself before making your purchase.

What are the alternatives to air conditioning?

There are several alternatives to air conditioning. However, the different methods often do not achieve the desired result in the long run. Nevertheless, we have tried to summarise the best alternatives for you:

  • Fans: They cool the room with a uniform air flow that can be adjusted in stages as desired. As a rule, most fans are noisy. Therefore, you should inform yourself in advance about the different models. The purchase and operating costs for a fan, on the other hand, are relatively low.
  • Natural cooling systems: These are a short-term solution. You can soak a towel in cold water and hang the moistened towel over the open window. Natural cooling systems are free, but in the long run they are not as effective and efficient as air conditioning.

To counteract the heating of the respective rooms, you should darken the windows every day and ventilate them vigorously in the morning or at night. This form of prevention provides the necessary cooling effect in the short term. However, this alternative should be seen as a supportive activity for your own air conditioning system, because it reduces the necessary operating power and at the same time lowers electricity costs.

How do I cool my room without air conditioning?

In the previous section, we looked at the alternatives to air conditioning in more detail
Here you will find a list of the different alternatives:

  • Axial and radial fans
  • Solar protection films
  • Heat pumps
  • Natural cooling systems

How does an air conditioner work?

The foundation of the air conditioner is the refrigeration cycle. The refrigeration cycle basically goes through the same steps in every air conditioner, so we have summarised the most important for you.

The basic principle of the air conditioner is based on the interaction between energy absorption and energy output of a refrigerant and the room air to be cooled. The refrigerant flows through the entire cooling circuit. The aggregate state of the refrigerant can change through the supply or release of heat or through a change in pressure.

The refrigeration circuit consists of four main components:

  1. Compressor
  2. Condenser
  3. Expansion valve
  4. Evaporator

First, the refrigerant is in a gaseous state. The compressor, also called a compressor, compresses the refrigerant. At the same time, the pressure increases and the temperature of the refrigerant rises.

Then, in the condenser, the refrigerant is converted from a gaseous state to a liquid state, in which heat is released to the outside air.

In the expansion valve, the pressure is reduced and the temperature is lowered. The pressure regulator transfers the refrigerant to the evaporator.

The evaporator provides the desired cooling effect. It absorbs the warm room air. The refrigerant extracts evaporation heat from the room air. The refrigerant evaporates and the room air cools down during this process.
These individual steps reflect a constantly repeating process.

What needs to be considered when installing air-conditioning systems?

The installation of an air-conditioning system differs according to the type of product. Here we mainly distinguish between floor-standing units and wall-mounted units. Floor-standing units are mobile and compact. They often consist of only one component and have no outdoor unit. They lead warm exhaust air out of the window via a hose and can therefore be installed by yourself.

Wall units are permanently mounted on the wall. Basically, a wall unit consists of an indoor unit and an outdoor unit. The indoor unit filters and cools the room air that is drawn in, whereas the outdoor unit discharges the warm air. The outdoor and indoor units are connected by a coolant pipe in the house. An example of wall-mounted units are split and multi-split air conditioners.


Split and multi-split air conditioners are permanently mounted on the wall. Basically, a wall-mounted unit consists of an indoor unit and an outdoor unit, which are connected by a refrigerant pipe in the house.
(Image source: Photo by Michu Đăng Quang/ Unsplash)
Please note that changes to the house wall must be agreed with the landlord or the authorities.

For this reason, drilling through the wall is necessary and should be done by a professional. Investing in an air conditioner is also an investment in the future. An air conditioner is ideally in use for several years, so you should not save in the wrong places.

A suboptimal installation of your air conditioner will result in an inefficient cooling performance. Conversely, you need a higher cooling capacity to achieve optimal cooling. The increased energy consumption results in increased costs. This cost effect can be prevented by professional installation.

For this, the professional should carry out a careful cooling load calculation. The following aspects must be taken into account when calculating the cooling load:

  1. Room size/room volume
  2. Geographical orientation
  3. Size and number of windows
  4. Average number of people in the room
  5. Heat emission of electrical appliances
  6. Shading devices/ solar radiation
  7. Room insulation

You should include these factors in your cooling load calculation so that your room can be cooled effectively. If you consider these aspects in your installation, your air conditioner can provide the right heat energy in a cost-effective and energy-saving way.

What should I do if the air conditioner smells?

The foul smell of the air conditioner is due to the formation and accumulation of bacteria, germs and harmful fungi. The air is only cooled, dehumidified and purified if the air conditioner is used and maintained regularly.


The air conditioner is the perfect breeding ground for bacteria and germs. That’s why it’s important to clean your air conditioner regularly. (Image source: Photo by Clay Banks/ Unsplash)

The air conditioner extracts moisture from the air in the room. The moisture often collects in the evaporator of the air conditioner. It provides the perfect breeding ground for bacteria and germs.

If a musty smell develops, it is immediately necessary to clean and disinfect the air conditioner. Professional disinfection prevents the development of harmful microbacteria that can enter the respiratory tract through the circulating air. For the maintenance of your air conditioner, you should first consult an expert.


Regular maintenance and cleaning of the air conditioner prevents the development of harmful bacteria and prevents unpleasant odours.

What do I do if the air conditioner no longer cools properly?

If your air conditioner stops cooling properly, you should keep a cool head. We have listed several possible causes for you:

  • Refrigerant: The lack of cooling is often due to an insufficient level of refrigerant in connection with leaking pipes. The refrigerant can be refilled in a vacuum. The individual lines must be replaced.
  • Technical problems: Compressor, condenser, expansion valve and evaporator are the four main components of an air conditioning system. If one of the four elements is damaged, the refrigeration cycle is interrupted and the air conditioner no longer cools. In this case, it is necessary to replace the respective individual part to enable heat absorption and heat dissipation.
  • Blockages: Dust deposits can lead to blockages. The clogged filter prevents optimal air circulation of the air conditioner and the refrigeration cycle is interrupted. Regular cleaning prevents clogging and ensures efficient performance of your air conditioner
  • Incorrect programming: Incorrect programming can lead to modern air conditioners not achieving the desired cooling effect. Therefore, you should compare the settings of your air conditioner with the recommended guide values in the operating instructions.

A repair should be carried out by a professional. If the air conditioner is not repaired by a professional, further damage can occur.

Is my health endangered by an air conditioner?

If the temperature fluctuations are too great, the body cannot adapt quickly enough to the constant temperature changes. The recurring cold shock results in a weakened immune system. A weakened immune system increases the risk of catching a cold.


An air conditioner must be cleaned and maintained regularly. Otherwise, the air-conditioning system turns into a virus breeding ground. (Image source: Photo by Vladislav Nikonov/ Unsplash)

Besides the cooling process, the regulation of humidity can also affect your health. Air conditioners extract moisture from the air in a room. This dries out the mucous membranes, which in turn are more susceptible to pathogens.

An air conditioner must be cleaned and maintained regularly. Otherwise, the air-conditioning system becomes a virus breeding ground.

Can an air conditioner also heat?

Basically, the main function of an air conditioner is cooling. Modern air conditioners often work according to the heat pump principle and can therefore not only cool, but also heat.

The air-conditioning circuit is reversed for the heating process. The refrigerant evaporates in the outdoor unit and thus absorbs heat. In the indoor unit, the refrigerant is converted into a liquid state by a compressor. This process causes heat to be released and the room air is heated.

According to experts, the temperature difference to the outside temperature should not exceed 6 degrees Celsius

This so-called air/air heat pump can run in heating mode at outside temperatures as low as -20°C. However, you should take this into account. However, you should bear in mind that the heating capacity decreases as the outside temperature drops. It should be noted that not every modern air conditioner has a heating function. Therefore, before purchasing your air conditioner, you should find out whether the air conditioner also has a heating function.

Image source: sutichak/