Air Filtration: Filtering Through
the Facts
Indoor air quality (IAQ) has most certainly been an increasing
focus of consumers who have realized recently that the indoor
air they breathe can have a significant impact on their health
and well being.
"Studies
have shown that people spend up to 90% of their time indoors and
that indoor air can be up to 100 times more contaminated than
outdoor air. As consumers read these statistics and findings,
they begin to recognize the need to protect their indoor environment,
and as such, greater numbers are requesting better
air filtration solutions", said Brian Baker, CM President
of Custom Vac Limited.
To the rescue. the American Society of Heating Refrigeration and
Air Conditioning Engineers (ASHRAE) who sets standards for the
Industry announced the new proposed air filtration standard 52.2.
This new standard replaced the old standard 52.1 adopted in 1968.
It was important to move forward and set the stage for the advancement
of newer technologies. Baker stated that, "the old standard made
it confusing for contactors like myself to select the best air
filtration systems for their customers, so it was no surprise
to me that consumers too, were experiencing difficulty in selecting
a filter that was right for them."
New Standard for New Technologies
Standard 52.2 created a new way of documenting the efficiency
of air filters and established the Minimum Efficiency Reporting
Value (MERV). Basically the standard looks at 12 different particle
size bands from 0.3 microns to 10.0 microns. The method of testing,
documents the minimum efficiency curves of filters by using six
different loading stages. The standard uses a synthetic dust to
simulate field conditions. By comparing these 12 different particle
size bands to the six loading stages, a minimum performance can
be determined.
As more products become available in the marketplace, it is necessary
to understand that not all air filters are rated the same way.
By selecting air filtration products based on the new standard
using and understanding the MERV value rating system will become
more important. Basically the higher the MERV value the better
the air filter.
A Solution for each Situation
Does every application demand a high-end or high MERV value air
filtration system? Baker said, "No, many situations could be significantly
improved by simply upgrading to a pleated air filter." Over 98%
of all bacteria known to man are over 3.0 microns in size and
moulds are actually even quite larger than bacteria, with the
vast majority over 3.0 microns. "If a pleated filter with a MERV
value of 7 were to be installed, the filter would remove initially
60% of the 3.0 micron-size particles and quickly rise to over
80 percent within days of the application," said Baker.
Since some filters like a MERV 7 actually increase in efficiency
over time it becomes important to replace them more frequently.
This is because as the air filter loads with particles the air
filter increases resistance to airflow resulting in a higher-pressure
drop creating a negative affect on the Heating Ventilation and
Air Conditioning (HVAC) equipment. Overheating of the furnace
heat exchanger, freezing of the air conditioning cooling coil
and/or if the HVAC system is interconnected with a ventilation
system, a reduction in air exchange. On the flip side, regularly
scheduled equipment maintenance and filter changes can extend
the life of the (HVAC) equipment, lower energy bills and result
in fewer breakdowns, which are all positives.
Get Professional Advice to Improve Air Quality
Baker strongly suggests, "Speaking with your HVAC technician or
contractor about improving your air filtration system prior to
the purchase of an air filter ask lots of questions, after all
it's your health."
While this article has dealt with only air filtration as one means
of improving indoor IAQ there are many products such as Ultra-Violet
(UV) lights, Heat Recovery or Energy Recovery Ventilation (HRV/ERV)
systems, Air Conditioning and Duct Cleaning, that can all have
a positive affect on improving indoor IAQ. Keep an open mind and
educate yourself by using the resources that are available to
you from places like Manitoba Energy and Mines and the Canadian
Mortgage and Housing Corporation (CMHC). They are very useful
publications and most are free of charge.
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