David Millward, Group Product Manager at Elta Group, explains a few key practical considerations for those tasked with installing ventilation systems.

A renewed focus on the air we breathe has highlighted the importance of good indoor air quality (IAQ). This is especially true in public spaces such as offices, shopping centres, schools, and a whole range of other buildings, which are increasingly tasked with improving IAQ.

Ventilation contractors have a critical role to play in delivering this. It requires an understanding of how to achieve good IAQ, but also a general awareness of some of the key considerations that can make a significant difference to system effectiveness.

Defining fresh air

With so much of the focus surrounding IAQ on the introduction of ‘fresh air’, there must first be a better understanding of what this term means. This applies to everyone involved in the ventilation supply chain, from government and manufacturers, all the way through to contractors and even the general public.

As things stand, there is a general misunderstanding that ‘fresh air’ is simply that which is brought in from outside. However, this does not go far enough and, in urban areas in particular, the air that is brought into the building can often contain high levels of pollutants.

Changes to Parts L and F of the Building Regulations are on the horizon, which will seek to provide a more concrete definition and promote more monitoring of IAQ in buildings. Contractors should ensure they keep up-to-date with evolving legislation as this is likely to impact the systems that they install in the months and years ahead.

Reducing noise and vibration

When it comes to installation itself, an often-overlooked factor in ventilation is noise, and it is often too late by the time it is noticed. Providing a comfortable internal atmosphere goes beyond just air quality, and this is where contractors can add value to their work.

For example, duct-borne noise can be reduced by using attenuators (also useful for airborne sound), or using lined fan types and duct lining. Structure-borne noise, meanwhile, can be reduced by isolating the fan from the structure and duct. Working to minimise the noise that a fan produces helps to distinguish a good installation from an okay one, and can be particularly important in quieter locations, such as a restaurant or library.

Vibration control is equally critical to the overall efficacy of a system, as this will contribute to noise as well as user comfort. A fan will inevitably vibrate, which can reverberate through the structure it is mounted to. Vibration isolators are the ideal solution to this problem, and should be selected to offer the minimum deflection required.

Care should also be taken to ensure vibration isolators are suitable for the fan and environment where it will be operating, and flexible duct connectors are available to aid in the reduction of both noise and vibration. These are just a few of the many options available to contractors.


Flexible ducting can be a fan’s worst enemy, as it introduces system resistance which means you have to use a much higher pressure and power output. A common issue lies with people incorrectly using a lot of flexible ducting in a roof space, purchasing say 10m when they only really need 3.5m and, instead of cutting it to size, creating a snake shape that places additional pressure on the fan.

This contributes to reduced airflow, increasing the risk of poor ventilation, and ultimately contaminants, viruses and colds etc. – something the population is hyper-aware of in the current climate. With this in mind, rigid ducting should be used wherever possible, with flexible ducting only used for final connections. It is also best practice to ensure all duct work is taut.

A reliable partner

Ventilation contractors are often relied upon by their customers – not just for their ability to install systems to a high standard, but also to be a fountain of knowledge on all things air quality. Now more than ever, an understanding of how to deliver good IAQ is a valuable asset, which makes it important to keep abreast of the latest developments and the most effective ways to install products.