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Ventilation system in the house - which ventilation suits my family home?

Ventilation systems have been around for thousands of years. As early as 2650 BC It is proven that the Egyptians built the first ventilation system to supply the pyramid of Cheops with air. Even then, people recognized the benefits of healthy indoor air: less tiredness, better concentration and generally greater wellbeing.

The British natural scientist Stephen Hales set another milestone in ventilation technology: in 1740 the concept for a ventilation system was developed, which is still used today in almost all ventilation areas in a further developed form.

Dezentrale Lüftungsanlage Haus

Healthy living space thanks to ventilation systems in the house

House construction is becoming more and more progressive: tight building envelopes through insulated roofs, external facades and multi-glazed windows ensure ever higher energy efficiency. However, the tightness of the building also means that a natural exchange of air in the house is becoming more and more difficult. While in the past natural ventilation was permanently guaranteed through cracks, joints or leaks in the masonry, nowadays the air is in the energy-efficient houses.
As a result, on the one hand, pollutants such as vapors from furniture and carpets accumulate in the room air. On the other hand, there is a faster rise in moisture, which greatly increases the risk of mold. The use of ventilation systems in the house is becoming more and more indispensable and ensures a continuous exchange of air. This increases the quality of the healthy indoor air and prevents mold growth. We would like to find out in the following: Which ventilation system suits your house?

Comparison: Installation & planning of a ventilation system in the house

In this chapter we will compare the planning and installation effort of the individual ventilation systems: Is professional ventilation planning necessary if, for example, funding is possible for the measure? Does the ventilation system have to be installed by a specialist company or can anyone do it themselves if necessary? Furthermore, we will consider the ventilation systems in the house in terms of their acquisition costs.

Comparison: installation & planning

Window rebate ventilation

Central ventilation

Decentralized ventilation

1. Installation & assembly
How big is the effort during assembly?

2. Eligibility
Which ventilation system can be funded?

3. Required expertise
How much expertise is required for installation?

4. Acquisition costs
How high are the acquisition costs?

Vorteile und Nachteile von Fensterfalzlüftung

Installation of a window rebate ventilation system in the house

The window rebate ventilation scores with very little effort during installation and assembly. Ventilation slots are inserted into the window frame without an electrical connection, thereby making the window leak again. The installation location and quantity are already specified by the window position and number of windows. Numerous window manufacturers already offer the ventilation slots in their windows from the factory. This type of ventilation is the (inexpensive) cheapest way to create a permanent exchange of air for moisture protection in the house. However, this type of ventilation is not one of the eligible measures in the course of an energetic renovation or a new building according to the KfW efficiency house standard. Due to the principle of “free ventilation”, air is only exchanged with heat loss, which is why this type of ventilation is not one of the energy-efficient solutions and, moreover, it is difficult to implement ventilation of inhabited units.

Installation of central ventilation in the single-family house

In contrast to free ventilation, the central ventilation system impresses with a heat exchanger for heat recovery, which is why it was included as part of the KfW funding program. However, the acquisition and installation costs of a central system are significantly higher, since a complex air duct system has to be laid and clad through the entire house. In new buildings, the pipes and ducts are often integrated directly into the false ceilings in the shell. A division into supply and exhaust air rooms is already determined at the planning stage. The location of the central ventilation unit must also be determined beforehand, as the air distribution system must converge here. The subsequent upgrade with a central system is therefore associated with considerable effort and increased costs and can only be carried out when the residential unit is completely renovated (house installation).

Installation of a decentralized ventilation system in the house

The decentralized ventilation system is the most flexible ventilation variant with heat recovery and can be easily implemented in both new buildings and renovations. The ventilation devices are installed in the outside wall of the house and therefore do not require a pipeline system. Especially in new buildings, the installation effort can be significantly reduced by using prefabricated assembly blocks, which also has a positive effect on the installation costs. Decentralized systems can also be retrofitted without any problems in the occupied state by means of core hole drilling. A partial renovation of one or two rooms is also possible. The acquisition costs for a decentralized ventilation system are between those of the window rebate ventilation and the central system. Due to the high degree of heat recovery offered by the decentralized ventilation devices, this controlled ventilation method is also part of the KfW funding programs. Contact us if you are planning ventilation with heat recovery.

Comparison: ventilation properties of every ventilation system in the house

In the following we consider the ventilation systems according to their specific properties: Does heat recovery take place? Can moisture also be recovered so that the air in the interior does not become too dry? How do the ventilation systems behave in terms of noise development? Do they cause intrinsic noise and or can they dampen the noise from the outside? In addition, the ventilation systems are checked for frost protection and intelligent sensors.

Comparison: ventilation properties

Window rebate ventilation

Central ventilation

Decentralized ventilation

1. Energy efficiency (heat recovery)
How high is the energy efficiency?

2. Moisture recovery
Is there the possibility of moisture recovery?

3. Sound & noise development
How high are the sound and noise levels?

4. Frost protection
Is there frost protection?

5. Sensor technology
Are there sensors that enable demand-driven ventilation?

Merkmale der Fensterfalzlüftung

Features of window rebate ventilation

The window rebate ventilation ensures basic ventilation for moisture protection. The air exchange takes place here depending on natural pressure differences through the ventilation slots in the window rebate. The close proximity to the window and soffit can cause condensation problems. In addition, there are high heat losses and direct sound transmission without sound insulation. A high level of noise protection cannot be guaranteed, especially in houses or apartments on busy streets. A healthy indoor climate exists with a humidity between 40 and 60 percent. The open structure of the window rebate ventilation means that healthy interior moisture is also lost more quickly. Dry mucous membranes, which are more susceptible to infections, coughing, eye irritation and skin irritation, can result.
There is no frost protection for the window rebate ventilation. In extreme weather conditions, the ventilation slots can therefore also ice up.

Merkmale einer zentralen Lüftung im Haus

Features of central ventilation in the house

In contrast to window rebate ventilation, there is no direct sound passage with the central ventilation system. Here, extra silencers ensure that both external noise and the transmission of noise from room to room (telephony effect) are absorbed. Heat recovery is made possible in the central ventilation system by the integrated heat exchanger (cross flow, counter flow or cross counter flow). However, the high operating costs reduce the energy efficiency of the central ventilation system. Intelligent sensors that enable demand-based ventilation in the house are available in central systems.
A preheater ensures that the system does not freeze up when there is frost and that the temperature in the house remains constant, even when the outside temperature is low. However, the frost protection provided by the preheater increases the operating costs of the ventilation system considerably.

Merkmale einer dezentralen Lüftungsanlage im Einfamilienhaus

Features of a decentralized ventilation system in a single family home

The greatest advantages of decentralized ventilation systems lie in their energy efficiency: On the one hand, the use of ceramic heat accumulators enables heat recovery of 80 – 90% to be achieved, and on the other hand, the fans have very low power consumption (around four euros per year per ventilation device). Here, too, sensors are available for demand-driven, individual ventilation of individual rooms or living areas. Direct sound transmission can also be present with decentralized fans, but additional soundproofing measures can help. In the meantime, the trend is towards new sound insulation devices that function as a sound absorber thanks to special linings made from high-performance insulation materials (e.g. the iV14-Zero with a sound insulation lining made from Inventin). External and internal noise are reduced to a minimum without reducing the air flow in the house.
In decentralized ventilation units, frost protection is provided by the reversing operation of the fan. Cold supply air and warm exhaust air alternate, which prevents the ventilation system from icing up from the start.

Practice check: which ventilation system suits my house?

In this chapter we examine the practical use of ventilation systems: Can the ventilation filter pollen, dust and odors from the outdoor air? Can you control the systems for individual ventilation? In addition, we consider the running costs of the individual ventilation options: What operating costs do you have to plan and how high is the maintenance effort?

Practice check of the ventilation systems

Window rebate ventilation

Central ventilation

Decentralized ventilation

1. Filtering
Is there protection against pollen, dust or odors?

2. Control options (automation)
Is there the possibility of moisture recovery?

3. Operating costs
How high are the operating costs?

4. Cleaning & maintenance
How high is the effort for cleaning and maintenance?

Praxis-Check der Fensterfalzlüftung

Practice check of window rebate ventilation

The “open” system of window rebate ventilation means there is no protection against pollen, dust or odors. In principle, the residents are exposed to the air quality that flows in from the outside. Once installed, the ventilation system does not lead to any additional operating or follow-up costs, as it does not require an electrical connection. Theoretically, cleaning and maintenance can be carried out by the user himself. In practice, however, cleaning can be difficult, as not all areas are easily accessible due to the angled structure. Because the installation location is tied to the window and the supply air is not preheated, comfort can be severely restricted if there are seats or even beds near the window rebate ventilation.

Praxis-Check der zentralen Lüftungsanlage

Practice check of the central ventilation system

With the central ventilation systems, a pollen-, dust- and odor-free living space is no problem thanks to the use of various filter systems. An F7 fine dust filter is often already available from the factory and is necessary to protect the device. Disadvantages tend to arise in the maintenance and cleaning of the ventilation system due to the extensive pipe and duct system: For reasons of hygiene, a cleaning interval of two years is strongly recommended. A maintenance contract with a specialist company is advantageous, even if this is associated with additional costs. Reductions also have to be made in terms of operating costs: Depending on the size and manufacturer, the power consumption of a central ventilation system is up to eight times higher than e.g. B. in the decentralized ventilation system. The ventilation can be controlled individually, but the entire residential unit is always ventilated.

Praxis-Check der dezentralen Lüftungsanlage

Practice check of the decentralized ventilation system

Even with the decentralized ventilation system, the air quality increases through the use of different filters, but higher filter classes can reduce the air flow to a small extent. Using an intelligent control system, you can define different ventilation zones in the house and ventilate each area individually.
With a decentralized ventilation system in the house, maintenance and cleaning can be carried out by the user himself and usually only takes a few minutes per device. The components can be cleaned with a damp cloth during cleaning and the filters can be replaced independently. The low operating costs, which are around four euros per device per year, are also positive.

Summary: advantages and disadvantages of every ventilation system for your house

Nowadays, new, energetic standards mean that houses are built so “tightly” that building owners have to consider the use of a ventilation system. Which ventilation system suits the needs of your home?
Choosing a ventilation system for your house construction is always a weighing of the pros and cons. Low acquisition and operating costs such as window rebate ventilation sound tempting at first, but in normal residential use the ventilation system quickly reaches its limits. Conversely, very high acquisition costs are not always offset by the greatest benefit. In the following we have listed a brief summary of the most important properties for you:

Summary window rebate ventilation system

Window rebate ventilation is part of free ventilation and differs fundamentally from other ventilation systems in that it is operated without a fan. Window rebate ventilation is an inexpensive and easy-to-implement solution for creating an exchange of air in the house. The principle of this ventilation only works if an air flow is established between two parallel sides of the building. Then, however, it only corresponds to the minimum requirements for ventilation, which is defined by DIN 1946-6 as moisture protection. In practice, this means that the free ventilation in an empty house can prevent the formation of mold if it is not regularly ventilated by opening windows. In a four-person household, window rebate ventilation alone cannot guarantee adequate moisture protection.
In terms of energy efficiency, the window rebate ventilation cannot keep up with the other common ventilation systems in the house. There are no operating / electricity costs, but heat is continuously lost through the open ventilation slot.

Conclusion central ventilation systems

Your house is continuously supplied with fresh air through the sleeping and living areas via a complex air duct system. At the same time, used air is transported outside from the extract air rooms such as the bathroom and kitchen. Heat is recovered through the heat exchanger inside the central device. This increases the energy efficiency of the house, which means that the ventilation system is included in the KfW program as an eligible measure.
A major disadvantage of the central ventilation system results from the complex planning of the ventilation system and the cost-intensive acquisition. The subsequent installation of a sewer and pipe system through the whole house is associated with a high level of structural effort, especially in the case of a renovation.
The operating costs of the central system are also significantly higher compared to other ventilation systems. Maintenance and cleaning should be carried out by a specialist company every two years and also have a negative effect on the household budget.

Conclusion decentralized ventilation system in the house

With decentralized ventilation systems, high heat recovery meets low operating costs. Decentralized ventilation is also the most flexible solution when it comes to controlled living space ventilation with heat recovery. It is suitable for new builds as well as for subsequent energy-efficient renovation, as it is installed directly in the external walls without a pipe system. The passage sound from the outside can get into the house through the wall opening. It is therefore important to equip the ventilation duct with appropriate soundproofing measures or to use decentralized soundproofing devices that prevent direct sound penetration from the outside (building installation).
The decentralized ventilation devices achieve the specifications for nominal ventilation according to DIN 1946-6. Together with 80 – 90% heat recovery, the criteria for attractive loans or even repayment grants from the KfW funding programs are met. The low operating costs of the decentralized fans are just as advantageous. Cleaning and maintenance are relatively uncomplicated and can be carried out by the resident himself in just a few steps

Vorteile dezentraler Wohnraumlüftung

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