CLEARING THE AIR: It happens to everyone. You get a
little distracted, overcook dinner, and then all evening,
someone’s asking, “What’s burning?!”
Cooking odors are just one of the many ways bad air
can linger inside your home. But many contaminants are
odorless and go undetected by the human nose. We
readily adapt to smells anyway, so your nose isn’t a very
reliable indicator of indoor air quality.
Besides odors, your home’s air may also contain moisture,
dust, mold spores, chemical fumes, combustion products
such as smoke and carbon monoxide, and other potential
irritants. Although most people aren’t significantly affected
by this indoor air cocktail, the long-term effects are
still being evaluated. As anyone with asthma or other
respiratory problems can tell you, poor air quality can
become a serious matter.
If you’re planning to build a home, you’re in the
perfect position to make it a healthy one by considering
several techniques for improving indoor air quality.
These techniques are recommended by the Partnership
for Advancing Technology in Housing (PATH),
a program of the U.S. Department of Housing and
Urban Development that promotes efficient technologies
to improve the quality, durability, comfort, and health
of your home.
VENTILATION: Healthy air starts with good
ventilation. Without it, everyday activities
like cooking (especially with gas), showering,
and even breathing often make indoor air
more polluted than the air outdoors. New
carpeting and fresh paint or varnish can
make it worse.
In most older homes, ventilation
happens the old-fashioned way:
through drafty doors and
windows and small leaks in
the walls and ceilings.
To achieve better energy
efficiency, today’s homes
are built “tighter”– so
tight, in fact, that
you may need to
incorporate additional
ventilation
into the heating,
ventilating, and
air conditioning
(HVAC) system to
ensure healthy air.
T h e A m e r i c a n
Society of Heating,
Refrigerating and
Air-Conditioning
Engineers (ASHRAE)
recommends a minimum
ventilation rate of 0.35
air changes/hour, which
means that about a third of
the air in your home should be
replaced by outside air every hour.
If your home is built tight, you may
want to consider an energy recovery
ventilator (ERV). This energy-efficient
device brings fresh air into the home and
recovers the energy from the heated (or
cooled) air as it is vented out of the house.
ERVs make more sense the more extreme
your climate is – whether hot or cold. They
also can be used to control humidity, which
is important in hot, humid climates in the
summer and in cold climates in the winter.
(In cold, heating-dominated climates, better
air flow and the introduction of humidity
to the indoor environment can help control
wintertime window condensation. In
humid summer climates, which are cooling
dominated, it can be critical to dry out
incoming air so that mildew or mold do not
develop in ductwork.)
HEATING AND AIR CONDITIONING: Your
HVAC equipment can help you maintain
good indoor air quality and comfort. Correctly
sizing both the air conditioner and furnace will
not only provide better air quality and comfort,
but also save you money on the initial
purchase cost and your monthly energy bills.
Correctly sizing the air conditioner will
help you control your home’s humidity in the
summer as well. Air conditioners provide the
greatest comfort when they run long enough
to both cool the air and remove the humidity.
An oversized air conditioner doesn’t run long
enough to dehumidify the air adequately. You
pay higher energy bills to run a bigger unit,
and the air feels cold and clammy. So resist
the urge to go with the “bigger is better” sizing
strategy or the rule-of-thumb approach of one
ton per 1,000 square feet. The builder should
calculate the size of the air conditioner using
Manual J, published by the Air Conditioning
Contractors of America.
Many homeowners opt for radiant floor
heating, which provides heat with hot water
coils (or heat-generating electrical wires)
buried beneath the floor. The heat is more
even and, because there is no forced air to
move dust around, rooms stay cleaner.
PATH research has shown that radiant
heat is as energy efficient as
conventional heat. It’s also very
comfortable.
Regardless of the type or
size of the HVAC system,
maintenance is critical.
Changing or cleaning
filters is key to the
performance of the
system. A good filter
will minimize the
dust, pollen, and
other contaminants
that are introduced
into your home.
N o r m a l f i l t e r s
remove dust and
some pollen, but
more efficient filters,
including electronic,
are available. Maintain
your filters by changing
or cleaning them at least
twice a year – once in
winter and once in summer.
(Some filters require more
frequent cleaning or replacement.)
Routine maintenance is also
critical to keeping systems operating
at peak efficiency and, for gas furnaces,
preventing exhaust leaks that can release
carbon monoxide into the home.
ASK THE BUILDER:
How did you determine the size of the
air conditioner and furnace? Did you
use Manual J?
Does my furnace use supply air from
the outside?
Where can we locate the furnace to
provide the most useable space?
What choices do I have for filtering
the air in the HVAC system?
Does an energy recovery ventilator make
sense for our home? How much would
an ERV add to the price, and how much
would it reduce our yearly energy bill?
Will upkeep be more difficult?
How will you keep the ducts clean during
the construction process?
CONTROLLING HUMIDITY: In most homes,
moisture build-up is related to the owners’
activities. A family of four releases about 2.5
gallons of water into their home each day.
During the winter in cold climates, this moisture
is often beneficial because heated winter
air can be very dry. However, in other seasons
and in areas where humidity is high yearround,
this moisture can result in
excess humidity, less comfort, and
possibly mold or mildew. An
indicator of excess humidity
in a home is water condensation
on the windows.
For most homes, the
easiest way to control
excess moisture is at
the source, typically
the stove or the
bathroom. Exhaust
fans will remove
that moisture – but
only if they’re used.
Family members
may be reluctant
to use noisy fans,
so be sure to select
quiet models.
Dehumidifiers are
great for controlling
humidity, which can
cause mold and dust mites
and trigger or aggravate
asthma. However, unless your
dehumidifier is vented outdoors
– and most portable units are not –
it will actually heat your home. During
periods of mild temperatures, a dehumidifier
might provide all the heat you need in
your basement. Keep in mind that you may
want to shut it off during the heating season
when your home needs more humidity.
A ventilation control system can also be
installed to control the air flow into the
home and maximize the home’s overall
HVAC efficiency. More elaborate central air
purification/ventilation/dehumidification
systems can do it all, but of course, they
cost more.
Basements can be an important source of
home moisture. Take measures to prevent
water from entering your basement by making
sure your builder slopes the ground away from
the foundation and extends the downspouts
so they discharge away from the home.
Read more about indoor mold and
mold control in “A Brief Guide to Mold,
Moisture and Your Home,” available at
epa.gov (click on “Air,” “Indoor Air,”
“Mold”), and in “Mold in Residential Buildings,”
available at toolbase.org (click on
“Mold, Moisture, and Leaks”).
ASK THE BUILDER:
Will we need to dehumidify our basement?
Will a portable ENERGY STAR®
dehumidifier do the job?
Is a central air purification/ventilation/
dehumidification system appropriate for
our home in this climate? How much
more would that cost?
How did you determine the size of the
exhaust fans?
Are exhaust fans ENERGY STAR®
qualified? How quiet are they?
Can the fans automatically shut off
after running for a preset time?
COOKING: While stoves have fans in the
range hoods, many homeowners do not use
them because of the noise. This allows cooking
odors, moisture, and grease to stay in the
home, decreasing air quality and requiring
more cleaning. For kitchens, options for quiet
range-hood fans include hood-mounted,
in-line, or exhaust-cap fans. Just like
selecting bathroom fans, selecting a
quiet fan with the correct capacity
is important. Again, ENERGY
STAR® qualified exhaust fans
are usually a good choice
because of their low noise
and excellent efficiency.
ASK THE BUILDER:
Is the exhaust fan
ENERGY STAR®
qualified?
If not, how
loud is it?
CLEANING:
B e c a u s e i n d o o r
air quality often
depends on the
cleanliness of the
home, select building
materials that are easy
to clean. Smooth floors
– such as wood, laminate,
tile, bamboo, or pigmented
concrete – provide such surfaces.
Low-pile carpet is also
easier to clean than deep-pile
carpet. (See “Building Technology
101: Flooring for a Healthy Home
and Planet” in the Winter 2005 issue of
Her Home.)
We have all used a vacuum that leaves a
dry, dusty odor in the room after use. That
odor is the dust leaking from the bag back
into the room. If you use a portable vacuum,
choose a model with effective air filtration to
prevent the release of small dust particles.
Some models offer High Efficiency Particulate
Air (HEPA) filters, which are among the
most effective filters available. You can also
buy more efficient “microfiltration” bags for
most household vacuums.
An alternative to a portable vacuum is a
central vacuum system, which makes it easy
to keep your home clean. Because the central
vacuum system can be exhausted to the outside,
the dirty air and dust that are collected
are not released back into the home. If you
select a central vacuum system, make sure the
system exhausts outdoors, not in the garage orbasement, and the exhaust does not affect
your use of the yard. An added advantage:
central vacuum systems are very quiet.
ASK THE BUILDER:
What options do you have for a
central vacuum system?
How will the system be installed
and exhausted?
OUTDOORS TO INDOORS: Homeowners
can unknowingly bring chemicals and other
contaminants into their homes from the
workplace, workshop, or yard. If you have an
outside door leading to a laundry or mud
room, consider using it as a changing room so
you can avoid bringing contaminants into
the home. Also use doormats or remove your
shoes when you go inside. This is especially
important right after you fertilize or use lawn
chemicals. Pets may also track such chemicals
indoors. (The use of lawn chemicals, especially
pesticides, can be reduced in most homes by
matching properly conditioned soils with
plants that require fewer chemicals. Always
follow the label during applications.)
Your windows may be your most effective
line of defense against polluted outdoor air.
Contaminants can come in through open
windows, so remember to close them if outside
activities like barbequing, mowing, fertilizing,
or painting may affect the indoor air. If your
windows are open during such activities,
don’t operate exhaust fans since they draw
air into the home.
Maintaining the quality of your home’s air
isn’t difficult, but it does take a good initial
design and a certain attention to detail. By
considering these issues during construction
planning, you can help design and build a
home that is healthy for years to come.
