Trickle vents in windows have long been used in the background as a means of complying with Part F of the building regulations (ventilation). While this has not always been straightforward, things have become more complicated with the new 2022 building regulations. It is worth remembering that the burden of compliance falls on the window installer.
For the glazing industry, the most relevant change in Part F concerns background ventilation: the requirement for ventilation is much bigger than it used to be. The way background ventilation is calculated has also changed: it has been amended to individual room values rather than whole-house figures.
Background ventilation is vital as it supplies outdoor air for the health of the building and its occupants. As homes become ever more airtight to reduce heat loss through air permeability, the importance of controlled ventilation increases. Even so, it is important to look at the bigger picture. Ventilation through a trickle vent in the frame or sash is counterintuitive to what we are trying to do to increase the overall thermal efficiency of windows, so it is vital that they are used only where needed.
How the regulations are interpreted will vary greatly. Every case has to be considered on its merits because the required ventilation can be achieved not just via trickle vents in windows but through other forms of ventilation such as mechanical whole-house ventilation systems. This means that, while the duty of care falls on the installer at the point of sale – not the homeowner, developer, fabricator or manufacturer – understanding the bigger picture for any particular installation is not always easy.
Trickle vents are often resisted on the grounds of aesthetics. It is well documented that homeowners are not keen on any increase in the number or size of trickle vents. Despite this, homeowners will not be able to sign a disclaimer; the installation must conform to building regulations. Any attempt to circumvent the rules would come back to the installer, not the homeowner. Understandably, installers may put in trickle vents whether they need them or not to be sure they are complying with the regulations.
Although the vents are not that much bigger than before, the way that they operate and the measurement of their airflow has significantly changed. As a window manufacturer, we are working to ensure we provide the best commercial offer for the customer and the right choice of trickle vent. We have changed our vents to be able to provide ventilation through the use of a single ventilator. We have also worked hard to adapt our manufacturing details and have achieved good colour and pattern matching to ensure that the vents are as unobtrusive as possible.
While we cannot tell installers whether a particular window requires trickle vents, we can guide them through the regulations. We also equip them with the documentation and solutions to meet the new regulations.
Managing director of Tradelink