Getting technical about ventilation

With the revisions to Part F of the Building Regulations soon to take effect, the interest in ventilators has never been greater. But are you aware of the technical difference between the different kinds? We talk to AW Louvers’ Wayne Irvine to discover more.

While introducing background ventilation is vital for the health of a building and its occupants, a gap through or above the window frame could introduce unwanted external noise to a property.

The Building Regulations have yet to include a requirement to resist the passage of external noise, but the effects of noise pollution on human health are becoming more understood, especially in built-up areas. For example, prolonged disturbed sleep could result in heart disease, and metabolic disorders such as diabetes.

Unfortunately, the understanding surrounding acoustics – the terminology, the way it is measured, and the different noise levels – often means that the wrong types of products are specified.

“There’s a lot of confusion around acoustics,” says AW Louvers’ managing director Wayne Irvine. “For example, there are different performance measurements that are referred to by different European testing houses. There is RW in the UK, and Dnew on the continent. There are also different decibels, different kilohertz.”

This can play havoc within the specification market, he said, because confusion could lead to the wrong products being specified. This is only likely to get worse as interest in ventilation increases.

“It’s quite often the case that somebody will ask for a product to meet certain specification, but that turns out to be the wrong specification because they don’t understand Dnew, C, CTR, the octave bands that relevant to aeroplane traffic, relevant to train traffic, relevant to car traffic, or relevant to groups of people, in fact,” Wayne says. “So, we’ve done a lot of work on that in the past and we’ve developed our products and technical support accordingly.”

On one recent successful project, AW Louvers provided glazed-in louvers for the Quintain Wembley Park residential development right under the famous Wembley Arch on Engineers Way. Due to its location, noise reduction was of prime importance because of the large crowds that could sometimes gather nearby.

To ensure that its products meet the technical requirements, AW Louvers has its products tested at SRL Technical Services which is an accredited acoustic performance lab in the UK.

“The mechanics of the testing are quite simple,” Wayne explains. “You have two rooms: you have one room which is sending room, and another which is the receiving room. Between these two rooms is a wall with your product placed in the middle.

“Then, the sending room sends a sound at different kilohertz, ranging from 50kHz to 8,000kHz. And then the receiving room picks up the sound for each of those kilohertz levels. The sending room will be much louder than the receiving room if the product you are putting into the test wall has good acoustic properties.

“The results are calculated to get an average, which is called the RW or the Dnew. This average gives you the sound reduction performance of your product: the higher your sound reduction, the better your product is acoustically.”

The SSH 2500EA acoustic trickle has a slot height of just 11mm, and can provide a sound reduction of 46Dnew in one acoustic model in open position, and 48Dnew with two acoustic models in open position.

“It’s important the ventilation specifications reflect the sound reduction in the open position, not the closed position, because you only get ventilation in the open position,” Wayne says. “The performance levels in the closed position are somewhat academic.

“Most of the other products are around the 42-43Dnew level at a 2500Ea. Obviously, with a 5000Ea, the performance goes down, but it’s still a market leading performance at that free area.”

AW Louvers’ range of ventilation products includes over-the-frame ventilators, through-the-frame ventilators and glazed-in ventilators. They are designed for a wide range of applications, balancing the ventilation requirements with superior noise mitigation.

The company’s website – www.awlouvers.co.uk – provides technical datasheets to help you specify the correct product for the right application.

“We know that understanding the acoustic performance of ventilators can be confusing when you are trying to meet the requirements of the revised Building Regulations,” Wayne says. “This is why we’ve invested in developing a market-leading range of products alongside comprehensive technical support.”