Bathroom ventilation

Bathroom ventilation is not the first thing that comes to mind when designing your bathroom, but it is an essential part that you cannot escape. In the bathroom you always have to deal with an enormous amount of warm air that has to be removed. If it doesn’t, it will remain warm and humid in the bathroom. This can cause a musty odor and mold, and it increases the chance that walls, floors, ceilings, furniture and sanitary facilities will break more quickly. And of course you don’t want that! You can prevent this by setting up a window regularly, but nowadays good bathroom ventilation is also a requirement, which can accelerate the removal of the warm moist air.

Read below how a bathroom fan works, how to calculate the required capacity and what types of bathroom fans are available.

How do bathroom fans work?

A bathroom fan connects to the standard 120-volt household electrical power in much the same way as lighting, for example. The fan can be connected to the same electrical circuit that powers a lamp. A wall switch controls the vent fan, and it may also have a timer that allows the fan to run for a prescribed amount of time. When the fan is turned on, the air is sucked out of the bathroom through the fan housing and down a plastic hose or metal duct to a vent on the roof or side wall of the house. A cover plate protects the exit point of the vent, keeping the duct closed when not in use.

Bathroom ventilation Bathroom inspiration


It is best to install the fan near the area with the most moisture, such as above the sink or near the shower. In an open bathroom you can place the fan halfway between the shower / bath and toilet. In a very small bathroom, centering the fan in the room is fine. When the toilet is in a secondary enclosure with a door, you may want to consider a second fan for this area.

  • Make sure the outer vent is working properly so that it closes completely when the fan is not in use. This prevents cold air from entering the house when the fan is not running;
  • Insulate around the flexible hose or metal duct leading from the fan housing to the outer cover. This helps to reduce the loss of heat from the inside to the outside;
  • Do not properly seal the opening under the bathroom door. Leave an opening at the bottom of the door so that the air discharged by the fan can be replaced with fresh air;
  • If you have a very high ceiling in the bathroom, it is wise to take a fan with a larger capacity;

Silent bathroom fan

Fans always produce noise. Therefore, pay attention to the noise classifications if you are going to buy a bathroom fan. has named the following bathroom ventilation brands as the most silent bathroom fans :

  1. SILEO series from Blauberg;
  2. SILENT series from Soler & Palau;
  3. SILENT Design series from Soler & Palau;
  4. Pro-Design bathroom fans KW series from Awenta;
  5. Nedco Fresh Intellivent.

Calculate capacity

It is important to get a bathroom fan with a capacity that is large enough for the size of the bathroom. Fan capacity is measured by CFM (cubic feet per minute), which is the amount of air moved per minute. In general, the larger the capacity the better, but it is possible that a fan is too powerful for the room, causing a negative pressure situation in the bathroom. This can disrupt the operation of the ducts or suck in cold air through windows. That is why it is important to first calculate how much capacity you need. Use the formula below to calculate the required capacity for the fan in your bathroom.

Height x width x length x 10 . Suppose you have a bathroom that is three meters high, three meters wide and three meters long, then you need a bathroom fan with a capacity of 3x3x3x10 = 270 m3 / h.

Bathroom ventilation Bathroom inspiration

Types of bathroom fans

There are three types of bathroom fans, namely ceiling fans, wall fans and inline fans . Read below what the differences are.

1. Ceiling fans

A ceiling fan, as the name suggests, is an exhaust fan that is mounted on a ceiling. These fans expel air upwards through the ceiling, which is discharged to the outside through a tube or duct. A ceiling fan is one of the most popular methods of ventilating a room. When choosing a ceiling fan, consider the required capacity, hole size and connection to the ductwork.

Bathroom ventilation Bathroom inspiration

2. Wall fans

A wall fan is particularly useful with limited ceiling or roof space. They come in a variety of styles, including wall fans located on the inside of the bathroom and located on the outside of the wall. A wall fan usually consists of a motor part (inside) with pipes or tubes that lead to an external ventilation. There are a few things to consider when installing a wall fan. If you are replacing an old fan, you must first remove the wall fan and measure the size of the hole. It is also important to measure the depth of the wall. For a new installation you have to make sure that your fan is suitable based on the depth of the wall. So you have to make a suitable hole in the wall to place the fan. Remember, if you don’t choose a fan with the exact same size, it is better and easier to make a larger hole.

Bathroom ventilation Bathroom inspiration

3. Inline fan

An inline fan is usually installed directly in the ceiling cavity and usually mounted between the lengths of the ducts. Inline fans are popular for bathrooms with no clearance or roof space for a ceiling fan. A big advantage of an inline exhaust fan is that it is much less noisy.

Bathroom ventilation Bathroom inspiration

Axial or Radial

In addition to the different types of fans, there is also a difference in the way the air is moved. This can be axial or radial> Below you can see what the differences are.

1. Axial

An axial fan is a fan in which the extracted air is drawn through the impeller, parallel to the axis around which the blades rotate. You could compare it to the operation of an airplane propeller. Most wall fans operate axially and are ideal for bathrooms, toilets and smaller spaces where the fan needs to be run directly through the wall or installed in a window.

2. Radial

Radial fans, also called centrifugal fans, draw air perpendicular to the inlet of the fan and turn the air out to the outlet by deflection and centrifugal force. The impeller rotates, causing air to enter the fan near the shaft and move perpendicularly from the shaft to the opening in the fan housing. This allows the fan to produce more pressure for a given air volume and thus the extracted air can be ‘pushed’ along much longer channels. Centrifugal fans are very suitable in rooms without outside walls. Bathrooms without windows or natural ventilation usually require a long pipe to reach the outside of the home.

Bathroom ventilation Bathroom inspiration

Bathroom ventilation Bathroom inspiration

Control bathroom fan

Bathroom fans can be operated in different ways. We have listed the most popular methods below.

  • Light switch : There are fans available that turn on when you turn on the lights in the bathroom or toilet with the light switch. If you turn off the lighting, the fan will also turn off. The problem is that in practice it takes a while before all the warm and moist air has been removed. Chances are, therefore, that not everything has been drained while you leave the bathroom. Of course it is also strange to leave the lights on.
  • Run-on timer : A bathroom fan with a run-on timer can be a solution to the above ‘problem’. The difference is that a fan with a run-on timer stays on longer after the lighting has been switched off. With some models you can set how long the follow-up period is.
  • Hygrostat : Then you also have bathroom fans with a built-in hygrostat. This is a moisture sensor that switches on or off based on the moisture content in the bathroom.

Bathroom ventilation Bathroom inspiration

Bathroom ventilation Bathroom inspiration

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Bathroom ventilation Bathroom inspiration

Bathroom ventilation Bathroom inspiration


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