Ventilation and health


Poor indoor air quality (IAQ), or indoor air pollution, is linked to a range of health conditions and is responsible for a signi´Čücant loss of healthy life years, loss of life and disease burden and the knock-on costs to the NHS, and the wider economy, are considerable.

UK citizens spend around 90% of their time indoors and around 16 hours a day on average at home. This means that their potential risk of exposure is many times that of pollution outdoors, especially considering that indoor air can be many times more polluted than outdoor air.

Poor IAQ has been linked to allergy and asthma, lung cancer, chronic obstructive pulmonary disease, cardiovascular disease and more recently even investigated for its links to dementia.

If your home has evidence of mould (usually black/discoloured patches on the walls) or if any of the occupants are suffering from respiratory or allergy problems, you should take a good look at the ‘healthy balance’ of your home.




Many buildings, particularly older ones, ventilate naturally by air passing through the building fabric. They also may have a ventilation system of some sort, but the question is “is it used?” You can air your homes by opening the windows. However, indoor air quality deteriorates very quickly when windows are closed again, e.g. when cooking or taking a shower, so we advise you to use whatever ventilation system you have in your home proactively.

With increasing insulation in homes they become more 'airtight' and the ability to ventilate naturally diminishes. In such situations mechanical ventilation can be used to overcome the risk of worsening indoor air quality.

The importance of ventilation is clearly recognised within Government backed building regulations that state the minimum levels of ventilation performance required in each home. However, awareness of regulations and ventilation requirements in the UK remains very low and many homes will show evidence of the health damaging side effects of poor ventilation.




If you can heat your home affordably and comfortably then look at your ventilation system to ensure it is working hard enough to improve the air quality in your home. If you don’t have any ventilation system installed, then look at the options below and consider an installation to suit your requirements.

Local Extract Ventilation

The most common method of ventilation in UK homes is a mix of natural and mechanical ventilation, for example trickle vents in the windows and intermittently running extractor fans in wet rooms, the kitchen, bathroom and toilet. Make sure that the trickle vents are open and unblocked and that extractor fans are clean and operating properly.

Don’t shy away from using the boost function if it is available at times when excessive moisture is being produced, e.g. when cooking or taking a shower. If your cooker hood or extractor fan is not working, buy one straight away to prevent further damage to your home and potential damage to your health.

Continuous Mechanical Extract Ventilation

If you have renovated your home with insulation and methods of reducing air leakage through the building fabric, you may find that the Local Extract Ventilation route is not effectively ventilating due to the larger amount of stale air and moisture that is created. In this situation it is best to invest in continuous ventilation which is either in the form of a central box system with ducts to applicable rooms or low level continuous running local extractor fans in the wet rooms. The latter approach is mostly applicable in existing homes where it is difficult to run ducted systems. Please note that although such fans run continuously, they can cost less than £5 per year to run so this is a tiny investment for such an important gain in your home, your personal comfort and your health.

Positive Input Ventilation (PIV)

These are central box systems (usually located in the loft in a house, or on a wall in a flat) with a duct that supplies fresh, filtered air into a landing area or hallway to ventilate the whole property. Rather than extracting air out, this method delivers air into the home to dilute, displace and replace high humidity levels to control condensation.

Mechanical Ventilation with Heat Recovery (MVHR)

MVHR is often applied in new, very air-tight and well-insulated buildings. Like Mechanical Extract Ventilation, they ventilate homes continuously but they give the added benefit of recovering heat from the extracted air and warming up the fresh air supplied to the building. In the future, it is expected that most new homes will be sold with these ventilation systems.

Please bear in mind that MVHR may not be the best solution if your home is poorly insulated and/or you leave your windows open.