Residential IAQ Retrofits
Answers to a Growing Need
2017 was the year the West burned. Heavy snowpack
and a damp spring across the northwest
yielded thick grass and underbrush growth. What
followed was one of the hottest summers on record, turning
the lush greenery into crisp tinder. It was a layup for
September’s lightening-riddled storm season.
By mid-month, there wasn’t a state west of the Mississippi
that didn’t have multiple wildfires. Smoke haze
from the Rockies could be seen for well over a thousand
miles. In some areas, the Air Quality Index approached
200, or “very unhealthy.”
A three-and-a-half-inch hole saw can be
used to cut a hole in ductwork or an air
handler for unit installation.
The generator can be wired either to
direct air handler contacts or through
a 24v transformer.
Simultaneously, Mother Nature ravaged coastal
Texas, then Florida. Days of rain and the ensuing floods
brought by Hurricanes Irma and Harvey stand in stark
contrast to the wildfires that charred the mountain
states, but there’s definitely one correlation: both natural
disasters present severe air quality challenges.
While fires present an immediate air pollutant danger,
the residual bonfire scent within nearby houses is also
a reality. Where hurricanes flooded homes, indoor mold
growth is almost guaranteed if moisture isn’t dealt with
swiftly and properly.
The modern IAQ challenge
For most homeowners across the country, these may
seem like isolated issues, but regardless of location, indoor
air quality (IAQ) has recently gained major awareness.
The weather seems to grow more extreme every
year, as do the allergies and breathing ailments we face.
More time is spent inside than ever before and information
on indoor air quality is widely available online.
Quite possibly the biggest factor, though, is modern
home construction. As part of the ongoing pursuit of
efficiency, houses are being built tighter. Thanks to
ASHRAE Standard 62.1, commercial buildings have
makeup air requirements. Makeup air is fresh air
brought into a building through ventilating (heating or
cooling) equipment. Private residences do not have makeup
air requirements. When extremely limited infiltration
is the only form of makeup air, airborne toxins—mold,
bacteria, viruses, fungi, Volatile Organic Compounds
(VOCs), particulates, etc.— have nowhere to go.
Those who suffer from asthma or allergies are generally
the first to notice poor air quality. Other times, the
problem is obvious to anyone in the building. A damp
smell is indicative of moisture and that’s often accompanied
by mold. “Dirty sock syndrome” is a perplexing
issue in hot, humid environments. In years past, retrofit
IAQ options were largely limited to larger filters and UV
lights, but the recent groundswell of interest has spurred
the development of new air purification
technology.
Many options
Ultraviolet light systems installed
within an air handler have proven
to be effective in many situations.
When used alone, the upfront cost
of a UV light is reasonable and installation
is relatively simple. Bulb
replacement is also a consideration.
UV lights only purify the radiation
with which it comes in direct
contact. That is, the system has no
effect on a shaded part of an AC
coil, and has zero residual effect
throughout the ductwork or home.
UV lights also don’t aid in filtration, so allergy symptoms
caused by inert particles aren’t affected.
However, UV lights aren’t the only option. Corona
discharge systems create positive and negative ions
through the use of a glass tube and metal mesh. The
ions destroy many airborne impurities without causing
any harm to building occupants, but the voltage
potential across a glass bulb can allow ozone production,
which is a health concern in and of itself. The tubes also
have to be replaced every year or two.
Photocatalytic systems include a UV bulb, but rather
than shining the light on the coil, the radiation is
concentrated on a titanium screen-like element. This
creates complex ions, which destroy pathogens, but also
run the risk of reacting with VOCs, in turn creating
unhealthy compounds.
Ozonizers, yet another technology, are very good at
decontaminating indoor spaces full of pathogens, but
cannot be used in occupied areas because of the health
risk that ozone creates. These systems are often used to
decontaminate a room while unoccupied.
An alternative
One new technology that avoids the use of UV lights altogether
is Cold Plasma Generation (CPG). CPG systems
create an electric or plasma field inside the ductwork. As
air flows through the field, molecules are highly charged,
creating natural positive and negative ions.
Dan Vastyan, Delta C, LLC
8 ICM/November/December 2017