If your bathroom has only internal walls, you can install a central exhaust fan. This will channel air outdoors through pipes or ventilation shafts. This is another relatively practical and cost-effective solution for windowless bathrooms. However, if you choose this type of ventilation, you will need to ensure a flow of fresh air back into the bathroom. You can use, for example, louvres on the bathroom door for this. One disadvantage of this exhaust fan: It has no heat recovery function, which means extra heating costs must be factored in.
What’s more: In windowless bathrooms, the installation of a fan is prescribed by law – according to the DIN 18017 standard in the federal building code for ventilation of windowless rooms. So if you live in rented accommodation, you can discuss this with your landlord.