The Benefits of Window Trickle Vents: Fitted Ventilation for Windows


Installed as part of the window frame, trickle ventilators can provide your home with constant, unobtrusive and secure background ventilation.

trickle ventilator window frame

The importance of background ventilation

In recent years, a drive to provide thermal comfort and increase energy efficiency has seen homes becoming better sealed against drafts than ever before.

However as homes are made more airtight, internal pollutants and condensation can have a greater impact on indoor air quality. If damp and pollutants cannot escape, the health of those living in a home may be at risk.

Effective background ventilation is necessary to provide a healthy and comfortable internal environment for the occupants of a home and this is why trickle vents are now installed as part of window frames.

What are Trickle ventilators?

Trickle ventilators (or trickle vents) provide background ventilation for a home when a window is closed, contributing to a healthy living environment by enabling unobtrusive and controllable whole-room ventilation.

A trickle vent is situated at the top of the window frame, it allows a small stream of fresh air to flow through from the outside into the room and can be easily adjusted through the use of cords, rods or simply by hand.

The benefits of installing trickle ventilators:

Cleaner air for your home

Providing effective background ventilation in your home may help to reduce the severity of health problems such as those brought on by respiratory ailments like asthma. It can also help to manage background air levels of pollutants such as carbon monoxide and carbon dioxide in your home.

Window Security

Trickle ventilators allow constant ventilation while a window is closed and/or locked, the opening for the trickle vent is very small typically less than 20mm wide which prevents human intrusion into your home.

Trickle vents operate 24-hours a day

Even at night and while you are away on holiday. If a trickle vent is left open it will provide background ventilation to your home. While your windows are closed and locked.

Using Trickle vent to reduce noise

Trickle ventilators provide ventilation to the room without the need to open the main window, reducing noise levels as a consequence. In noisier locations, such as near a busy road or an airport, the trickle vent can be designed with additional acoustic options giving even more noise reduction benefits.

Condensation reduction

Some homes may have an existing problem with condensation, especially in colder weather. Replacing older windows with modern double glazed units which include a trickle vent, a suitable thermal break in the window frame and a wide air gap between the glass panes may improve the condensation problem, and could potentially reduce consequent mould growth and internal surface damage.

Cost effective

Trickle ventilators are a passive home ventilation system. With the lowest cost route for the provision of background ventilation without the need for air bricks. Because trickle vents are passive there are no ongoing electricity costs and they allow you to have more control over the room ventilation than traditional air bricks.

Are trickle vents mandatory?

When replacing a window, having a trickle ventilator built into the casement window frame is not mandatory unless the existing window has one. If it does, the new trickle ventilator must offer at least the same airflow performance as the existing trickle vent.

However, if you are considering replacement double glazed windows and the existing window doesn’t have a trickle vent, it is recommended to request one when replacing it.

Trickle vent designs

Trickle vents can be added to the frame of new casement windows, sash windows and roof windows. They are suitable for wooden uPVC steel and aluminium frames. They can not however be retro fitted to an existing window frame.

Consider how tall the window will be, if you need to get onto a chair to open or close the trickle vent then it is unlikely you will regularly use it. You may want to move it from the top of the frame to the bottom/sides or consider adding rods or cords to your new window order so the trickle vent can be easily opened or closed.

Trickle vents can be fitted to all new window frame materials including PVC-u, timber, steel and aluminium.

  • Through Window frame design

A through frame trickle vent design is often positioned through the top of the window frame. The trickle vent is integrated into the window frame itself.

  • Over window frame design
window trickle vent over frame design

An over the frame design is used when it is not possible to fit the trickle vent through the window frame. The trickle vent makes provision for the ventilation to be routed over the frame or head of the window.

  • Glazed into the window
window trickle vent glazed in

The trickle vent is fitted into the glazed window area along the top of the sealed double glazed glass window unit.

For more advice and information about ventilation in your home, get in touch with a local GGF Member company.

Related topics

– A guide to home ventilation
What is condensation and why does it occur on windows?
Window condensation – where the water vapour comes from
Where condensation can form on a window and how to reduce it
Top tips on reducing condensation room by room