December 11, 2023, 4:23 pm | Read time: 3 minutes
A window rebate ventilation system constantly brings fresh air into the home—even when you’re not actively ventilating. However, this mechanical ventilation system is controversial. myHOMEBOOK explains the pros and cons and reveals how much installation costs.
Poor air quality in an apartment or house usually means there hasn’t been enough ventilation. While unpleasant odors can be annoying, they’re often harmless. In rooms with limited air exchange, humidity levels can quickly rise, partly due to the residents’ breath. Over time, this can lead to mold in damp corners and moisture damage to the building structure, which is far from harmless.
Proper ventilation can be challenging during the cold season. Especially with exorbitantly high energy costs, no one wants to stand in a cold room only to heat it again. A ventilation system can help ensure fresh air indoors, but these devices are expensive and require ample space. If you lack both, you can install a window rebate ventilation system. But what exactly is behind this term? And why is such a ventilation system controversial?
What Is a Window Rebate Ventilation System?
A window rebate ventilation system is a type of ventilation sluice that operates mechanically in continuous mode without electricity. Also known as window rebate ventilators or simply FFL, these small valves are integrated between the window frame and sash. Fresh air flows from outside through the window rebate ventilators into the interior, while used air exits. This ensures a constant air exchange. A wind pressure safeguard prevents the air exchange rate from rising too high during strong winds. In other words, despite the wind, drafts don’t pass through the window frames.
The system only works if the house or apartment has windows facing different directions. Simply put, fresh air flows in from one side and exits from the other.
What Are the Advantages of a Window Rebate Ventilation System?
Unlike a ventilation system, window rebate ventilators are relatively inexpensive. They can be retrofitted into existing windows by a professional. Additionally, a constant air exchange is guaranteed, even if the residents are not home to ventilate. This can help prevent mold formation, albeit to a limited extent. Nowadays, window rebate ventilators are so well integrated into the window system that they’re no longer visible. They can also be easily cleaned when the window is open.
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What Are the Disadvantages?
While the small air valves are sufficient to ventilate the home to a minimum standard, regular shock ventilation is still necessary to maintain adequate living comfort. Additionally, even with constant incoming air, window rebate ventilators fail to combat widespread mold effectively.
Another issue: While the ventilation brings fresh air into the home, it can also bring in unpleasant odors from outside, such as street exhaust. For pollen allergy sufferers, window rebate ventilators can be more of a curse than a blessing, as the air openings are not suitable as pollen filters and cannot be easily retrofitted with filters.
How Much Do Window Rebate Ventilators Cost?
Simple FFLs are available at specialty stores for between 15 and 20 euros. High-quality models or those for specific window systems can cost more. If you plan to equip the entire house with window rebate ventilators, you should budget around 500 euros.