Air Quality

Posted 26th January 2013


During last year’s weird weather, we had periods of heavy rain following drought.  This caused extreme stressing of the sewage network, resulting in the overflow of vast quantities of raw sewage into the Channel, which made many of our most popular beaches unusable.  None of us would like to swim in polluted water.

However, we seem to be less fussy about breathing polluted air.  Research has shown that in many houses, schools and offices, we breath in a cocktail of chemicals which can be harmful to our health.  These result from the activities in our buildings, the furniture, machinery, paints, and carpets.

Most houses are naturally ventilated, research shows that ventilation rates can vary hugely, depending on wind speed and weather conditions.  0.3 air changes an hour per person is recommended.

Below some remedies are reviewed.

1.  Simplest Solution – Open the Windows

Opening windows can provide rapid purge ventilation to remove odours and humidity, nothing could be simpler.

Many replacement windows, especially PVC, do have trickle vents.  These allow a small constant airflow needed for fresh air.

2.  Reduce Pollution Sources

Think carefully about the chemicals you bring into your buildings.  Cleaning agents and ‘air fresheners’ are usually harmful in concentrations, consider simple natural alternatives such as lemon juice, vinegar, or bicarbonate of soda.  Remember that for every litre of chemicals under your sink, many more will have been created in production, much ending up as pollution.

3. Use Your Extract Fans

Most mechanical extract fans are noisy and annoying, but they serve a purpose.   Replace defective units, clean them, this can reduce noise and electrical consumption.  If they have filters, have you ever removed, cleaned or replaced them?  Cooker hoods should be cleaned regularly.

4.  Bedrooms

Many of us sleep with the windows closed for security reasons, in which case we are often in one room with no ventilation for 8 hours.  Trickle vents are of particular use, or put the windows on the night vent setting if PVC or aluminium.

Well ventilated and cooler bedrooms reduce the development of mould and dust mites.

5.  Air Vents

During the winter air vents through walls/windows are often blocked up to reduce draughts, but these may be the only means of providing fresh air to a room.  Avoid the temptation!  It is possible to fit baffles to prevent wind blowing through, whilst still providing a flow of air.

Over-sized trickle vent

6. Mechanical Ventilation with Heat Recovery (MVHR)

The most reliable method of ventilating a building is through a continuously running extract system, sometimes coupled to a continuous air supply.  These have been shown to provide the best air quality, with CO₂ levels little different to the outside air.  They maintain constant air supply regardless of the weather and wind conditions.

When correctly designed and installed they are quiet to operate, and cost only around £30 to £50 per year to power.

However, the filters need regular replacement or cleaning, just like in your car.

7.  Maintenance

If you have a ventilation system, when did you last check the filters?  According to industry figures, around 20,000 units are sold every year in the UK., but only around 3,000 filters!  Time to check yours?