Article authored by our Director, Barney Richardson:
This month I deviate again from refrigeration requirements for compliance to meet skills training and registration with SAQCC Gas.
To follow on from last month’s discussion I recently read an article regarding a complaint that air conditioning causes illness through colds and hay fever. One point made is that and air conditioner either a through the wall or window type or a split unit does not bring fresh outside air into the space. The popular choice of air conditioner these days is a midwall split air conditioning unit for many applications.
Many people falsely believe that air conditioners bring fresh outside air into the office space or house. For some people with allergies this is of concern when there is high incidence of pollen through spring and summer. There are lot of pollutants in the air from outside and inside from furnishings such as carpets, pets and paint. The fact is that air conditioning units do not bring fresh air in from outside.
In hot humid weather the air conditioner is switched on then the windows of the office or home are tightly shut to keep the cool air in and not to waste cooling energy. The penalty of that is that no fresh air coming into the space.
If you inspect your air conditioning unit, you will see that there is an inside unit, the evaporator and an outside condensing unit. These are connected by copper refrigeration pipes with a refrigerant flowing between the two units, either as a liquid going to the indoor unit or suction gas going back to the outdoor unit. The air flowing through outside unit is just outside air, the air blowing from your indoor unit is recirculated air inside the room. The indoor unit has a return air intake grille which includes filter to collect dust. No fresh outside air is introduced through a split air conditioner unit. The outdoor unit has a fan to push air across the condenser coil, taking heat out of the refrigerant and cooling it down to be recirculated to the indoor unit in liquid form.
If indoor air quality is a major concern to you additional fresh air ventilation steps must be taken to ensure clean air and that volatiles and pollutants are not re recirculated. A dedicated ventilation system for a space may be required. A purpose designed fresh air ventilation system to supply fresh filtered air to the office space and to displace stale air will ensure the quality of indoor air. Filtered ventilation is used to remove the pollutants and odours, dust, bacteria and carbon dioxide. To avoid indoor air stagnation requires the continuous circulation of fresh air through a correctly sized ventilation system. It may not always be possible to have a dedicated ventilation system for a home, but leaving one or two windows slightly open will create circulation and dilute stale indoor air.
To repeat last month’s advice for ventilation be aware of minimum fresh air requirements. A good rule of thumb is 6 l/s to 12 l/s per person dependent on the activities in the in the space or alternatively 1.2 l/s /m².
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