Responsible Refrigeration
BARNEY RICHARDSON
Barney Richardson is the director of South African Refrigeration and Air
Conditioning Contractors Association (SARACCA) and sits on various other
boards within the HVAC industry, including the South African Qualifications
and Certifications Committee for Gas (SAQCC) Gas.
THE QUALITY OF AIR
IN A HOME, SHOP OR OFFICE
By Barney Richardson
While I have been writing about being responsible when working on
refrigeration systems and being registered as an Authorised Refrigeration
Gas Practitioner, I have not commented on the quality of the air in a
home, shop or office.
F
ar too often when a room air conditioner is installed the user
assumes that the windows can be closed to keep the cool
air in and the hot air out. However, when there is no new fresh
outside air coming into a room there is a perception of staleness
in the air.
Air quality problems caused by pollutants are all contributors
to indoor problems. These pollutants are:
• Moisture in the form of high humidity and moulds in damp
walls;
• Bacteria and viruses;
• Organic compounds that are volatile and come from
furnishings;
• Building materials and paint;
• Smoke;
• Pesticide sprays like doom and the common mosquito
repellent sprays; and
• Dust particles.
The common symptoms of poor air quality indoors are dryness of
the nose, throat, and irritation of the eyes. There can be coughing
and sneezing from a sinus congestion as well as sensitivity to the
pollutants listed above and common allergies. There can also
be tiredness and fatigue with headaches. The adverse effects
of these symptoms result in poor work performance in the
workplace and absenteeism.
Ventilation of a space is the process of bringing in fresh filtered
air and displacing used air in a space to ensure the quality of
indoor air. Filtered ventilation is used to remove the pollutants
and odours, dust, bacteria and excess carbon dioxide. To avoid
indoor air stagnation requires the continuous circulation of fresh
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air through a correctly sized ventilation system. Complaints
about the freshness of indoor air have increased as buildings are
built with greater tightness and low infiltration. Air quality has
become a major discussion point with architects and HVAC design
engineers. The trend to reduce energy usage has prompted
designers to reduce the fresh air flow through the air conditioning
system but this is not solving the air quality problem. A large
proportion of the heat load can be the fresh air component of the
system which has to be considered.
The factors that affect air quality are the tightness of the
building mentioned above and what air infiltration can be
expected. The types of windows and doors are important
considerations when trying to determine infiltration. Wind
pressure is a force on a building that further complicates any
assessment because of the variable nature of wind. In tall
buildings the ‘stack effect’ can be a serious factor. For our
consideration here we can ignore the ‘stack effect’ if we are to
concentrate on the application of room air conditioners in homes,
small offices, shops and workplaces.
The quantity of outside air introduced through a ventilation
system must be based on dilution of odours and pollutants. It
must be remembered that most room air conditioners especially
split units do not have a fresh air feature. Therefore, one has
to consider a separate outdoor ventilation system with filters.
Remember that the more air introduced, the more air is added to
the heat load.
For 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. Greater fresh air volumes per
person have been promoted for smoking designated areas. RACA
RACA Journal I March 2020
67