Requirements, classification, and recommendations for the bathroom fan

The bathroom fan is an essential element of a home's ventilation system, as it is responsible for extracting the stale air from this space in the house. There are different extractors on the market, depending on the direction of the airflow or its adaptability to the flow rate or humidity. All of them must guarantee maximum efficiency from an energy perspective.

Requirements of the current regulations regarding energy efficiency

The RITE stipulates the following requirements:

• Fans must be chosen that come as close as possible to the maximum performance level.

• If the ventilation system is of variable flow, the previous requirement must also be met for average activity conditions throughout the season.

• The specific power of the systems must be justified. This way, the power consumed by the extractor for each unit of airflow passing through the system can be stipulated.

• It is mandatory to indicate the category of each of the extractors. On one hand, SFP 1 and SFP 2 (for ventilation systems); on the other, SFP 3 and SFP 4 (for air conditioning systems).

• The specific power absorbed by each of the extractors will depend on the category to which they belong:

• For fans of category SFP 1, the power must not exceed 500 W/(m3/s).
• In the case of fans of category SFP 2, the power will range between 500 and 750 W/(m3/s).
• Those belonging to category SFP 3, the power will range between 750 and 1250 W/(m3/s).
• For category SFP 4, between 1250 and 2000 W/(m3/s).
• Category SFP 5, the power can exceed 2000 W/(m3/s).

Classification of fans

Depending on the direction of the airflow, we can classify fans into three different categories:

• Axial or helical: the airflow enters and exits in the direction of the axis.
• Centrifugal: the airflow enters and exits in a radial direction.
• Helico-centrifugal: the airflow enters in an axial direction and exits in a radial direction.

Depending on their adaptability:

• Extractor with humidity-regulated extraction mouth. Allows air renewal through a variable flow depending on the relative humidity rate of the space (indicator of occupancy).
• Extractor with self-regulating extraction mouth. Allows the equipment to be programmed to inject and extract a constant airflow. It avoids pressure differences between habitable spaces, as the flow is constant, which protects the health of users.

Whatever the type of bathroom fan, it is important to consider the noise aspect and choose those that do not exceed acceptable decibel levels in residential buildings. Therefore, it is advisable to select those with a complementary timer flow (half an hour) controlled by a presence sensor that causes the system to turn off when it is not necessary for it to be in operation. On the other hand, it is advisable to choose those that are easy to assemble and install.