Advantages And Disadvantages Of Positive Input Ventilation Systems

By Ruth MacEachern

Product Manager

When weighing up the correct ventilation systems for your home, you might wish to consider the advantage of a positive input ventilation system. This can help to circulate air around your home, helping to prevent problems such as damp, mould, and condensation, while also providing fresh air and scattering the build-up of pollutants.

What is positive input ventilation?

Many traditional, ‘passive’ ventilation systems rely on fixtures, such as vents and air-bricks with gaps to allow air to pass into and out of the home. There are some disadvantages to this passive approach, though. These areas can be forgotten about, become neglected, blocked, or even be papered or bricked over. The air flow through a modern house is not always optimal, even if all the vents are clear, and these gaps can also introduce drafts or allow heat to escape.

Modern homes are increasingly energy efficient, meaning that they are better at retaining heat, but it is also important that they are well-ventilated. Without good air flow, moisture can build up, leading to condensation, damp, and mould. Research has shown that the average four-person family creates 112 pints of moisture each week, from breathing, cooking, washing, and boiling the kettle.

The measures we take to improve energy efficiency, such as installing double glazing, cavity wall, and loft insulation, can all help to prevent natural ventilation, meaning that air-flow needs a helping hand. A positive input ventilation (PIV) system provides this helping hand in the form of a motorised unit, installed in the loft space of your home. This will draw air from the outside, filter it of impurities and pollutants, and use positive pressure to circulate the air through the home.

In a similar way that the environment inside a fish tank is prevented from becoming slimy and murky with the use of a pump, a PIV system can prevent the less-visible, but the still unhealthy build-up of moisture and pollutants in your home.

By Ruth MacEachern

Product Manager

What are the advantages of positive ventilation?

There are several advantages to this sort of low-pressure ventilation. It ensures a constant flow of fresh, filtered air through your home, regardless of the conditions inside or outside the house.

This can be crucial to prevent the build-up of moisture and associated problems, which can include the growth of mould and damp patches. A damp environment can exacerbate some health problems, such as asthma, can cause damage to your home that is expensive to rectify, and generally create an unpleasant environment.

The pressurised circulation of clean, filtered, air through the house can also help to remove pollutants that enter from elsewhere in the house, as well as dispersing mustiness and odours. A PIV system can lower the humidity in the house, which can also prevent dust mite populations from thriving. This can be another benefit for children and adults in the house who have asthma or allergies.

As warm air rises, lofts are often comparatively warm spaces, and as this air is moved by the fresh air coming in, it can have a slight but significant impact on the temperature of the house.

A good quality PIV unit will run on a low-energy motor that has low running costs.

Are there any disadvantages to PIV?

The set-up of a loft mounted positive input ventilation system means that it is only appropriate for houses with a suitable loft space. There are many homes, including some designs of bungalows, flats, and houses, where this type of system is not suitable, however other positive input system could be utilised, such as a wall mounted system.

As already noted, warm air rises, and so the loft spaces can be warm during the summer or when the house is well heated. Depending on the design of the house and insulation measures, however, lofts can be cold in the winter and this colder air can be distributed by a positive input ventilation system, having a slight cooling effect on the rest of the house.

They can also be a more expensive solution than other ventilation systems such as an extractor fan, although the problems that can arise in a home with inadequate ventilation can be far more expensive in the long-term. There are some slight disadvantages to the system but the benefits provided by PIV will almost always outweigh these drawbacks.

When weighing up the correct ventilation systems for your home, you might wish to consider the advantage of a positive input ventilation system. This can help to circulate air around your home, helping to prevent problems such as damp, mould, and condensation, while also providing fresh air and scattering the build-up of pollutants.