From: Anthony C Jones, Chairman, National Federation of Glaziers

The double glazing market has experienced a surge in demand during the pandemic. Consumers have been spending more time inside, considering how to make their homes more comfortable, safe, and efficient.

There are proposed amendments to building regulations in England and Wales with a consultation period ending on the 12th April. We feel that consumers need to be made aware of the practical effects of these amendments before they are due to come into force.

There are proposed amendments to Part L (conservation of fuel and power) and Part F (ventilation). Some amendments to Part L will be positive for consumers, as they will impose a minimum B energy rating and ultimately reduce household energy bills.

However, a proposed amendment to Part F, which regulates a home’s ventilation, is concerning. It aims to make trickle vents mandatory for most replacement windows, which was unsuccessfully put forward in 2006.

A good quality trickle vent adds £50 on average to the price of each replacement window, which is, in our view, an unnecessary extra cost to the consumer which quickly adds up across an entire house. 

We estimate that the introduction of mandatory trickle vents will cost the consumer around £60 million per year. And to what benefit?

Our arguments are:

1.       It is obvious that windows can simply be opened to allow for sufficient ventilation, rendering trickle vents pointless. 

2.       They compromise the aesthetics of a consumer’s brand new, otherwise attractive windows.

3.       Trickle vents have a detrimental impact on a window’s efficiency and integrity.

4.       Trickle vents can let moist, cold air into the property along with noise, pollution, and small insects. 

All of this is contrary to energy saving principles. Making replacement windows more expensive and less efficient will deter potential consumers from investing in energy efficient products.

Understandably, many consumers who are forced to have trickle vents in their windows will simply cover them to keep out unpleasant cold air, noise, pollution, and insects. From experience, we know that it is not uncommon for customers to ‘blank off’ trickle vents: filling them in internally in an attempt to restore some of the window’s prior efficiency. These consumers are ultimately left with an unsightly, expensive feature on their windows which offers them no use or benefit.

We have conducted a survey of a large number of industry professionals and business owners. Over 90% of respondents echoed the above four concerns regarding the trickle vents proposals. 

To summarise, consumers will be paying disproportionately for a ‘benefit’ which takes away their choice as to how they ventilate their homes. On this ground alone, there will be considerable resistance from consumers, and it is more than likely that many companies will refuse to fit them. The current self-regulatory regimes (such as Fensa and Certass) check only 1 in 100 installations, and trickle vents can be retrofitted in any case.

As mentioned above, Part L amendments will require a tightening of insulation values up to a minimum B rating. The fitting of trickle vents work counter to this policy: they are little more than a hole in the window frame with only a piece of plastic (typically 2mm) separating the outside from the inside. 

The substantial additional cost of trickle vents will disincentivise consumers, and its implementation next year will come at a very unfortunate time as the economy recovers from the pandemic. The National Federation of Glaziers was founded in 1991 to encourage excellence and integrity in the glazing industry. We are a consumer and trade association, balancing the needs of both the consumer and the industry. As a social, not-for-profit business, we are run by experienced people from the glazing industry and are happy to give advice and assistance to anyone who needs us. Our website gives full information about who we are and what we do: