Tackling Trickle Vents – as published in Glass Times mag
No-one can argue against the necessity for background ventilation to be delivered in the built environment. But, the requirement to provide this background ventilation via trickle vents in windows is leading to misconceptions in the level of ventilation present in a property and causing issues around acoustics and aesthetics for our industry.
Ventilating the home has never been more important than now. Historically, our buildings had ill-fitting doors and windows, open fireplaces (or ventilated chimney breasts), ill-fitting loft hatches providing many opportunities for internal stale air replacement. However, over recent decades we have been doing more and more to improve the air-tightness of our buildings by gasket sealing all openings and even spring-loading and adding brushes to letterboxes.
The need for whole dwelling ventilation is explained in Approved Document F (ADF), emphasising its importance in the provision of fresh air and removal of water vapour. Both of these factors are huge contributors to the health and wellbeing of occupants and also to the wellness of the building by addressing the battle against condensation.
Unfortunately, the requirements to install trickle vents when replacing windows fitted with them or when the room is not ventilated adequately, leads to a number of issues because the drive for their use seems to be more from the cheap means of provision as opposed to their effectiveness.
With this is mind, Certass is starting a new campaign to lobby government on amending the regulations surrounding the use of trickle ventilators in windows. It has been a controversial issue over a number of years due to the majority of occupants, consumers, installers and manufacturers being not in favour of their usage.
Providing trickle ventilation within a fenestration product, simply because it is cheap and convenient, does not make it a suitable solution for whole house ventilation. Especially when that solution is rendered ineffective due to human non-acceptance and intervention.
We rely on manual operation by consumers, who just as easily could open or close the window itself and without an easy way to enable consumers to understand the impact of bad ventilation, the situation is getting more urgent especially when combined with the increasing number of overheating deaths in the UK.
On top of this, consumers consistently complain about the sound issues caused by the vents, especially when they live in busy areas, often leading them to insert silicone within the opening. And the use of curtains and/or blinds often hide the ventilators and any effectiveness throughout the year.
As an industry, we all understand these issues – but our communication to government is critical. We need to make it absolutely clear that the high levels of thermal insulation in a well-engineered and well-manufactured window is ruined by the provision of an unrestricted passage of external air either adjacent to it or through it.
Government’s own research in 2015/2016 into ventilation and indoor air quality in 80 new homes, found that less than 4 percent of the naturally ventilated homes met the guidance in ADF with respect both to trickle ventilator provision and intermittent extract fan air flow rates.
Further improvements in thermal performance of windows will enhance the detrimental effect of trickle ventilators on the overall performance of the product. And as air tightness in buildings increase, so will the need for a more effective means of whole dwelling ventilation.
Whether Government will review the position is debatable, but when no stakeholder group is happy with the outcome, surely it is time to think again. Even the World Health Organisation (WHO) is clearly expressing its negative view on standards of natural ventilation for indoor air quality, dampness and mould for a variety of reasons.
In a perfect world, consumers would want a well-insulated home with no draughts, where you can replace stale, moist, low quality air with fresh air from outside without having to turn on the heating to warm it up. They would also be very aware of the potential health concerns that can be caused by bad ventilation in the home and appreciate the need to open a window.
Government moved in the right direction with some of the commentary under the Green Homes Grant but maybe it is time that the regulation is focussed more on what can be achieved rather than halfway steps that are more about cost than effectiveness.
It is time to look again and consider alternatives to trickle vents, such as a drive toward whole house passive stack ventilation systems. Perhaps then our industry can stop punching holes in good, high-performance products and ruining the thermal and acoustic performance, for consumers who resent the requirement to do so.