Moisture, dust, pollutants – you don’t want these inside your home so make sure every room is well ventilated, every day. A small, discreet vent in your window frame can do the job without you having to lift a finger. Here’s how it works. 

Everyone knows that you need efficient ventilation for a good indoor climate, otherwise your home can become an unhealthy place to live. Ideally, this means airing out every room, every day to avoid a build up of damp and polluted air which can affect your health and wellbeing, and can also damage your home.

In practice, however, it can be hard to make sure our homes get enough fresh air every day, so how much easier would life be if our windows did this for us? And they can – windows with trickle vents allow fresh air to flow continuously around the home, even when you are out or asleep.

Friskluftventil åbnes med et klik

How do trickle vents work?

Trickle vents are inserted into the internal window frame, which means they can’t be seen from outside. With a single click, the vent opens to provide a small gap that allows fresh air to enter the room, until you click the vent shut. To begin with we recommend leaving vents open continuously, unless it’s really cold outside or blowing a gale.

Trickle vent function


One vent is not enough, however. To circulate fresh air efficiently you need trickle vents in a number of windows, plus air bricks in the walls (if possible). Together, the vents will either draw in fresh air and expel stale air, depending on how the air flows around your home.

What do trickle vents look like?

Rationel trickle vents are designed to be discreet, so they lie flush against the frame when closed and are only slightly raised when open. Externally, you can’t see the vent at all. We usually insert trickle vents into the side of the frame but they can also be installed into a transom window, in which case an external rain screen will also be fitted as protection from the weather.


Trickle vents are not enough so remember to ventilate

While trickle vents certainly help keep your home ventilated they are not enough, on their own, to ensure a good indoor climate. So remember – create a through draught across your home, two to three times a day, by opening windows in different rooms for five to ten minutes. That’s all it takes!

Good advice for ventilating

Why is ventilation so important?

Fresh clean air is vital for a healthy indoor climate. A poor indoor climate, where the air is full of moisture, dust and pollutants, can damage your home:
• Good ventilation prevents condensation – small water droplets inside the home caused by warm moist air meeting a cold surface, such as a pane of glass or a wall.
• Condensation can be a particular problem in winter, making your house damp and encouraging mould growth
• This is why ventilation is particulalry important in winter, when temperatures drop