By September 29, 2017 Read More →

It’s a breeze! Recommending effective ventilation

It is important for wholesalers to have a good understanding of ventilation options in order to help contractors source the most appropriate product. Robert Dennis, Product Marketing Executive at Airflow Developments, reviews the key factors to consider before identifying which solution will offer the optimum benefits for each individual project.

In an effort to reduce heat loss and improve energy efficiency, our buildings are becoming increasingly sealed. However, this means they are also more susceptible to mould, damp and condensation – marking and potentially damaging ceilings and walls. This is particularly true in areas such as kitchens and bathrooms where users generate high levels of heat and moisture through cooking and bathing.

Arguably a greater concern is the negative effect poor indoor air quality can have on the health of building occupants. A 2015 report by My Health My Home revealed that more than 15.3 million UK homes are at risk of Toxic Home Syndrome – a condition that occurs when airborne allergens such as dust, pollen and mould spores build-up and pollute the internal environment due to inadequate ventilation and in turn harm human health.

As such, wholesalers need to be well informed to ensure only high performance products are chosen, along with the most appropriate system for specific areas within buildings is selected.

Approved Document F

Building Regulations Approved Document F and the accompanying Domestic Ventilation Compliance Guide set out the requirements for extract ventilation air flow rates for common ‘wet’ rooms that typically require enhanced ventilation. These are:

  • Toilets: 6 I/sec (22 m3/hr)
  • Bathroom/shower rooms: 15 I/sec (54 m3/hr)
  • Utility rooms: 30 I/sec 108 m3/hr)
  • Kitchens adjacent to hob: 30 I/sec (108 m3/hr)
  • Kitchens without a cooker hood: 60 I/sec (216 m3/hr)

It is important to ensure that any recommended solution complies with Approved Document F when installed. However, fan performance statistics can be misleading as these figures are often listed for fan operation without appropriate ducting or grilles in place. As such, this is not always an accurate representation of the ‘installed performance’.

If the added resistance of ducting and/or grilles has not been taken into account for a fan that has been installed, its performance could drop below the minimum required level for it to comply with Approved Document F.

The sound of silence

As our buildings become increasingly hermetically sealed and properly insulated, it is reasonable to assert that noise from outside the building will permeate less. Additionally, with improved acoustic performance any noise coming from within the building will be more noticeable to occupants.

In response to this, a number of new products have been released, marketed as ‘silent fans’. The Oxford English Dictionary defines ‘silent’ as ‘the complete absence of sound’, so with this in mind, we must ask whether these fans are being marketed with this definition in mind.

Essentially, it is important to recommend fans that provide a low energy, effective extraction solution, whilst offering the quietest possible noise output on all settings.

Fans with low dB(A) levels must be assessed in terms of the extracted air that they deliver in situ.

If a fan is sacrificing optimum flow rate for the lowest possible noise levels then a building’s fabric will still most likely deteriorate and a person’s health can become negatively affected by the harmful pollutants created.

Wholesalers should consult specification sheets to ensure the most informed decision is made when helping a customer to select a ventilation solution. In addition, fan performance curves help identify which extraction fan will offer optimum benefits against a system pressure resistance for each individual project.

Intermittent fans

Intermittent extractor fans should be installed in all wet rooms. They can be turned on manually via a pull cord or switch, or automatically by humidity or motion sensors – coinciding with cooking and bathing activities. The common types of intermittent extractor fan are:

  • Centrifugal and mixed flow fans – are powerful fans that are appropriate for installation on walls and ceilings. Their power enables them to work very efficiently against system resistance, making them the ideal choice for installations with longer duct runs.
  • Axial fans – are quiet fans that are ideal for through-the-wall and installations with shorter duct runs. Providing high performance with a slim profile, they are generally suitable for use with ducting up to a maximum recommended 1.5m length, connecting directly to an external outlet or grille.

One such example of an intermittent extractor fan is Airflow’s QuietAir QT100. Quiet Mark approved, the unit is a highly energy-efficient axial fan with a long-life ball-bearing motor that provides 40,000 hours of operation. With its flow smoothing design, it can deliver installed performance over longer duct runs. It is fitted with a room refresh interval timer that enables automatic extraction at pre-set times.

The unit also benefits from an extremely low noise level (25 dB(A)) for a fan of this performance. Ideal for toilet and bathroom areas, the QuietAir QT100 exceeds the requirements of Building Regulations Approved Document F.

Mechanical Extract Ventilation

As electrical wholesalers will be aware, the key difference between traditional intermittent ventilation systems and Mechanical Extract Ventilation (MEV) systems is that MEV units feature a continuously running fan.

Ideal for residential properties, a centrally mounted unit is typically installed in a loft space or cupboard and ducted around the home to each ‘wet’ room – extracting the moist air to prevent damp and mould from developing.

For further protection, adjustable units are available where the level of ventilation can be adjusted based on changes to air quality, e.g. humidity. This ensures any excess moisture is swiftly removed from the room.

Localised versions, known as decentralised MEV (dMEV) units are also available. These single room fans can be a useful addition in highly insulated properties as it provides a quiet and unobtrusive ventilation option. Again, a continuously running fan extracts moist air that causes condensation and mould.

Whether in a domestic or commercial setting, electrical wholesalers will become increasingly asked by customers to recommend appropriate ventilation solutions. With pressure being placed on ensuring high levels of indoor air quality to comply with current Building Regulations, wholesalers need to be aware of the options they have available to them to give the best possible advice.

Pictures: Airflow’s QuietAir QT100 is Quiet Mark approved. The unit is a highly energy-efficient axial fan with a long-life ball-bearing motor that provides 40,000 hours of operation.