The kitchen ventilation grille and its relationship with noise

When designing a ventilation system, we must take into account the noise that it may generate. The kitchen ventilation grille (and those of the other damp rooms in your home), one of the main components of the system, has a direct impact on the noise of the ventilation systems.

Standard UNE-CEN/TR 14788:2007 IN

According to the UNE-CEN/TR 14788:2007 IN Design and sizing of ventilation systems in residential buildings, ventilation systems must be designed in such a way that they meet the requirements for noise protection (acoustic insulation) between homes or between a home and the outside. It should be ensured that ventilation systems are quiet, placing special emphasis on the noise that the system can transmit between homes.

If it generates noise, it should be uniform and monotonous. Relatively high noise levels will be allowed in spaces where an activity can be carried out, with fans operating intermittently. However, noise levels will not be acceptable when they prevent listening to the radio or holding a phone conversation. In bedrooms, especially at night, low acoustic contamination must be maintained. In no case will the fans of the ventilation systems generate noise levels above what is acceptable outside the building.

Types of noise

To comply with current regulations, it is essential to think of ventilation systems that minimize noise levels as much as possible. We can talk about two types of noise: direct noise and indirect noise. We refer to direct noise when the noise is generated by the ventilation system itself (the ventilation system is the source of the noise and, at the same time, its means of transport). The components of the ventilation systems that can lead to this direct noise are the fans, the supporting structure of the ducts, and the valves. If the source of the noise is outside the ventilation system, we talk about indirect noise. The system, in this case, serves as the means of transport for the noise but not the source of it. This noise, which may come from outside the home, enters through the ventilation openings.

Depending on the ventilation system used, the external noise, the system noise, or the transmission of sound will be more or less important. In natural ventilation, there is no system noise, and the transmission of sound is irrelevant, while external noise is a factor to be taken into account. In mechanical ventilation, however, all three factors are important.

Requirements for distributors of air conditioning and ventilation equipment

All components, including the kitchen and bathroom ventilation grille, of the ventilation and air conditioning systems must comply with the noise protection regulations. According to the CTE DB HR, system suppliers must provide the following documentation:

• The sound power of systems that generate stationary noise (pumps, extractors, grilles, etc.)

• The mechanical stiffness of the ducts, the maximum load of the anti-vibration systems, and the damping capacity.

• The acoustic absorption factor of the absorbing elements used in the duct layout.