Modern ventilation technology for your home


  • Why modern ventilation systems?
  • Different types of systems
  • Paying attention during planning
  • Conclusion

Nowadays modern ventilation systems are more than just sheer extravagance, in fact, they are an essential part of complying with building physics in energy-efficient new buildings. With the help of a fan, used up air from inside the house is transported outside through ductwork that is usually kept as short as possible. At the same time fresh air from the environment is sucked into the house. This is done either by a separate system for supply air, or a by natural balancing of negative pressure.

But what do we need to pay attention to when installing a modern ventilation system? Which benefits and disadvantages does each system have? The following guide will give you a summary of different ventilation methods and help you in planning a modern home ventilation unit.

Why modern ventilation systems?

Ever since the end of the 20th century modern ventilation systems have become increasingly popular. This is strongly connected to the development of passive houses, because this type of building is generally designed to be airtight. Walls are heavily insulated and, contrary to old buildings, closed windows allow almost no circulation of air. The result is an outstanding efficiency regarding heat reservoirs, however the impermeability of air goes both ways. Not only is there no supply of fresh air in the house, but humidity caused by breathing, sweating and even cooking cannot leave the house.

Applied and maintained correctly, modern ventilation systems prove to be rentable in the long run, because they save heating costs and also prevent mould growth on building fabric and reduce possible costs for renovation. Furthermore, they operate virtually silent, so that there is no sound pollution either. Basically, they can even prevent the latter: If you are living on a street with a lot of traffic, you probably know the problem that once a window is opened, the noise level inside the apartment increases considerably. With ventilation system, windows do not even have to be opened.

Improvement of air quality

Another advantage of controlled home ventilation is the significant improvement or air quality.
Residents in privately owned homes do not have pay attention to opening windows anymore once humidity in the room is perceived as too much. Humid air is automatically removed, resulting in a pleasant indoor climate.

The possible threat of temperature loss is prevented with the help of a heat exchanger. Those devices extract heating energy from the transported air and keep it inside the house. Thus, providing you with cosy temperatures and fresh air at the same time.

Spread over a period of 24 hours the human body releases up to one and a half litres of water, even with only little physical stress. On top of that, the following sources of humidity are added:

  • cooking
  • bathing
  • showering
  • doing laundry
  • drying laundry
  • watering flowers and other plants

If humidity results in condensation on windows it‘s time to air the room.

In this context it is very important to make sure that excessive humidity is transported out of the house, to prevent damage on building materials such as mould.

In summer a ventilation system works almost like an air conditioning system, even though it has less of a cooling effect. However, it does keep out the heat if insulated well. Often it is because of manual airing, meaning opening windows and doors, that unwanted heat is getting into the house.


Apart from air quality, the hygiene of a household also be impoved with a ventilation unit. By using special filters in the supply air duct, pollen, fine dust and other pollutants are kept at bay.

Furthermore, there are often pollutants inside the house that we are not always aware of. Lacquers, plastic or building material can partly release dissolvers, softeners and formaldehyde. A constantly circulating, filtered air flow therefore ensures not only that harmful substances stay out of the house, they also rid the inside of pollutants.

Individuals suffering from allergies can breathe a literal sigh of relief during spring-time. Special filters are keeping harmful pollen outside.

Reducing the relative humidity with automated ventilation also helps prevent the spreading of bugs and vermin – particularly mites. They prefer warm rooms with high relative humidity as it is their ideal habitat that provides everything they need for quick reproduction. Mites prefer to infest big, cushioned surfaces, like a mattress for example. Especially people with asthma or allergies to dust are sensitive to increasing mite populations. Various secretions of those microscopic arthropods are what cause allergic reactions.

A suitable ventilation ultimately prevents growth of fungi and mould. Almost a fifth of the population has already encountered damages in their own home that were caused by too much humidity. Mould growth is not only harmful to building material, but also to our health – particularly allergy sufferers.

Different types of systems

Basically, the individual systems can be divided into centralised and decentralised installation. If a ventilation system for the entire living space seems to be too expensive and inefficient for you, an automated ventilation of single rooms might be better for you. In this case the unit is mounted between the outside and inside wall of the room. This option still offers the possibility of heat recovery.

Centralised ventilation systems on the other hand, are much more complex, and need to be divided again: mere exhaust air systems and a combination of exhaust and supply air. In the following we are taking a closer look at the characteristics of each system.

Exhaust air systems

Exhaust air only systems are mainly used in damp locations. Kitchens, bathrooms and WCs generally have a higher amount of humidity that the rest of the flat. Therefore it makes sense to use special fans, such as bathroom fans or window fans, in order to transport humid air through a duct to the outside so that mould can be prevented.

Now a negative pressure is created in the individual room as the air has been extracted. This is evened out by pulling in air from the other rooms. In turn, those rooms are balancing out their negative pressure by themselves with the help of special slipstream openings on the house walls.

Exhaust systems have the benefit of little installation efforts and have more favourable prices as they do not require ducts for supply air. However in most cases this type of system does not include a heat exchanger, meaning that valuable energy is lost. Furthermore there are not as many options for using filters.

Poor installation can also lead to cold air from the outside flowing into the inside of the house during winter, which is an issue especially for people that are sensitive to low temperatures, resulting in discomfort. When mounting the device on the outside wall of the house, it can sometimes happen that the acoustic insulation is reduced as well. That is why it is essential to be foresightful when drafting a concept, so that the noise level is kept at a minimum.

Advantages and disadvantages of an exhaust air only system:

Combined exhaust and supply air systems

This type of ventilation is generally applied throughout the entire house and flat respectively. The core of these systems is the central exhaust air unit. It collects thermal energy of the removed air and transfers it onto the outside air that was heated up before with geothermal energy. This ensures a maximum efficiency in keeping the heat inside the house.

Furthermore, used up air is not only removed from damp rooms, but also from living and bedrooms. The quality of the air in those rooms increases and the threat of pests spreading is reduced significantly, because they require humidity for survival.

Aside from investment and maintenance costs the combined ventilation system offers many benefits: Altogether the value of a building is increased by the installation of an exhaust and supply air system. Because: The more efficient the heat recovery device is, the less needs to be spent on heating the house. Furthermore, there are no restrictions by draught in regard to well-being.

A combination of exhaust and supply systems is a particularly good choice for people with allergies, the air that is coming into the house from the outside is being thoroughly filtered. Due to the longer duct that reaches from the place where the air is coming in and where it is brought into the room, there is no loss of quality in terms of sound insulation.

Advantages and disadvantages of a combined ventilation system:

Paying attention during planning

If you are looking to install a suitable ventilation system in your home, you should ask yourself a couple of questions:

  • How are the conditions (personal habits, structural)?
  • What is the suitable type of system (centralised, decentralised, exhaust only, combination)?
  • What are the main components (fan, control)?
  • Which documents are required (contract specifications, duct system diagram)?
  • Which mistakes should be avoided (pollution, wrong choice of device)?

Planning a modern ventilation system requires more than just drawing a system diagram.

Planning a modern ventilation system in your home begins with taking inventory of the current circumstance. Your own behavioural patterns are a main aspect. For example it should be taken into consideration if there are people with allergies or smokers.

Also you need to question how often the doors are open during heating periods. The airtightness of the house and its location in windy or calm regions have to be analysed as well.

The possible types of systems have already been described above. Whereas decentralised systems can score with a low cost factor, centralised ventilation offers heat recovery, filtered air and better sound insulation.

As far as documentation goes, technical drawing of the duct system plays an important role. On top of that it might also make sense to have a functional specification (offered to the customer by an installer) as well as a product requirements document (specifically demanded by the customer) and an acceptance certifacte.

Frequent errors that can be prevented in advance are possible pollution of the components, an irritatingly high sound volume of the system or incorrect tuning of air distribution, air transportation, or control of the entire system.

Planning phases of a ventilation system:


When it comes to implementing a modern ventilation system, there are many options one can choose from. The fundamental question that needs to be answered is whether the home has the required level of air density, so that a centralised system pays off. In old buildings this is often not the case, which is why decentralised ventilation of single rooms is often the better choice. It is also important to consider if it should be a exhaust air only system of it it makes more sense to use a combination. Each system has its own advantages and disadvantages, so it is not possible to give a generalised recommendation, it always depends on the individual case.

An extensive planning process first analyses basic conditions of the personal living situation: Whether doors are opened during heating periods, or if the house is in a windy location. Afterwards, it is necessary to choose the suitable type of system and to pay attention to selecting the right equipment. Ideally, devices that consume only little power, operate quietly, and are easy to clean and maintain. Finally, one should not forget to sufficiently document the finished system, so that maintenance and cleaning efforts can be kept at a minimum.

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