August 2016

The Numbers of Air Quality in the UK

Over 90% of asthma sufferers in the UK that experience breathing difficulties in the office feel that their workplace isn’t properly ventilated

If there is no Indoor Air Quality intervention over and above existing requirements to combat the effects of improved build quality that by 2050 there will be:

  • An 80% increase in asthma sufferers (currently the UK has the highest rate in Europe)
  • TVOC concentration up to 60% above WHO 24 hour limits
  • NO2 concentrations 30% above WHO annual limits

There is 5.4 million asthma sufferers in the UK – highest number and highest percentage of the population in Europe

Indoor air can contain over 900 chemicals, particles and biological materials that can have an effect on health – we spend 90% of our time indoors

Building dampness and mould – a direct result of poor ventilation – can be associated in up to a 50% increase in a variety of respiratory issues

Below you can see diagrams that showcase the impact poor indoor air quality has on human health (taken from IAQ and Health: A Summary of Evidence published by My Health My Home and from the The World Health Organisation's Breath Life Campaign) :

Burden of Disease from poor indoor air quality in the UK in 2010. Firstly by disease, then by exposure

What are the different types of ventilation?


Infiltration is the exchange of air from inside the building to outdoors. This takes places for a number of reasons. The build quality of the building plays a major part, as the more air tight the building is, the less porous the building is and there are fewer opportunities for the indoor air to escape from the building. Air tightness is becoming a growing problem within the UK, as the improved build quality is causing new homes to be increasingly air tight.

Passive stack ventilation

This is an extremely basic type of ventilation. It contains no moving and requires no electricity. It works by having an extract point from each wet room, which in essence becomes that room’s chimney, i.e. 5 wet rooms equals 5 chimneys; these extract points cannot be merged into one. The hot air from the wet room rises and the Venturi effect, from the wind blowing across the top of the pipes, causes the air to be sucked up the pipes and removes the air from the home. All other living areas should have trickle vents in the windows and walls to allow the outdoor air into the premises. Passive Stack systems are virtually uncontrollable as they are dependent on the outdoor environment. Passive Stack Systems can also be affected by tall structures as they require good levels of wind to be effective.

Extractor fans

Simply speaking, extractor fans mechanically remove the air from the wet room. Typically extractor fans (classed as intermittent fans in the Building Regulations) are used in wet rooms such as bathrooms, kitchens and toilets to remove the moist air from the room; maintaining a high quality indoor air environment. Building Regulations within the UK require a set degree of ventilation to take place. This is dependent on the type of wet room. Toilet fans are expected to extract 6 l/sec, bathrooms are expected to have an air flow rate of 15 l/sec and kitchens are either 30 l/sec when adjacent to the hob or 60 l/sec when fitted elsewhere in the kitchen. These flow rates are a minimum bench mark set by the Building Regulations and can increase based on the size of the room and the house itself.

Intermittent fans are also legally required to fully adhere to the 2016 ErP (Energy Related Products) Directive that came into force 1st January 2016. This requires all fan manufacturers to provide a product fiche and label on both their product and on their website to any fan that operates above 30W. You will be familiar with ErP through washing machines and fridges – whereby they were given an A+ - G rating based on their green credentials. Surprisingly, not many ventilation suppliers to the UK adhere to this legal requirement.

You can easily find the ErP Product data for the award winning iCON range of intermittent fans on the Airflow website as well as ErP data for the entirety of the residential intermittent fan range including: Loovent eco, QuietAir and Aventa.


dMEV stands for Decentralised Mechanical Extract Ventilation. Extractor fans are placed in the wet rooms around the house and run continuously at a low extraction rate (its trickle rate). When the humidity level increases within these rooms, the unit will then increase its extraction rates (up to its boost levels) to remove the excess moisture from the room.

The minimum flow rate for dMEV fans are 13 l/sec for kitchens, 8 l/sec for bathrooms and utility rooms and 6 l/sec for toilets and en-suites. However, in reality, these ventilation levels are dependent on the size of the house and could be higher than these. You can learn more ab