32 • OIL
&
ENERGY
TODAY’S ENERGY EFFICIENT HOMES ARE
tighter than ever before because reduced
infiltration/exfiltration results in higher
energy efficiency and lower bills. Good stuff
all around, but there is a downside.
In the “good old days” when fuel was
cheap and building codes were less strin-
gent, our homes were loosely built with
poor insulation and multiple openings to
the outside ranging in size from the gaps
in ill-fitting windows and doors to open
chimneys. Dollar for dollar, tightening
up the home provided the best return on
investment and so we did it, oftentimes
with financial incentives.
Add to this the newer stricter building
codes, and our housing stock today uses
almost half as much fuel for heating as it
did in 1978. This reduction is all the more
significant considering that over 35 million
homes have been added during that time.
Of course there have been huge improve-
ments in the appliances that we use to heat
and cool our homes, but a large part of those
savings, if not most, are the direct result of
sealing the building envelope.
LIFE MOVES INDOORS
Our lifestyle has also changed over the
years. More time is now spent indoors both
at work and at home. This is particularly
true during the humid days of summer
when we keep our homes comfortable with
air conditioning. The last 30 years has seen
an increase of almost 30 percent in the
amount of homes with air conditioning.
So it seems that for much of the year, the
only time that a significant amount of fresh
air enters our homes is when somebody
opens a door!
No wonder then that we have seen an
accelerated interest in indoor air quality.
There was a time not so long ago that
outdoor pollution was commonplace. The
smog that we hear so much about is gener-
ally caused by emissions from industry and
power generation. London suffered through
the “Big Smoke” in 1952, a four-day event
caused primarily by coal emissions, which
is reputed to have resulted in the premature
death of as many as 12,000 people with an
additional 100,000 made ill. China boasts 16
of the world’s 20 most polluted cities, which
is the result of increased industrialization and
automobile use. And here in the US, while
many cities still experience smog events that
necessitate public warnings, the Clean Air
Acts of the 1960s have done much to improve
the quality of the air that we breathe.
However, the EPA tells us that indoor
air quality is a serious issue: “In the last
several years, a growing body of scientific
evidence has indicated that the air within
homes and other buildings can be more
seriously polluted than the outdoor air in
even the largest and most industrialized
cities,” the EPA writes.
Since most of us no longer burn coal or
generate our own electricity, where are these
pollutants coming from? EPA explains:
“These include combustion sources such as
oil, gas, kerosene, coal, wood, and tobacco
products; building materials and furnish-
ings as diverse as deteriorated, asbestos-
containing insulation, wet or damp carpet,
and cabinetry or furniture made of certain
pressed wood products; products for house-
hold cleaning and maintenance, personal
care, or hobbies; central heating and cooling
systems and humidification devices; and
outdoor sources such as radon, pesticides,
and outdoor air pollution.” Whew!
VOCS ARE UBIQUITOUS
A significant contributor to this condi-
tion is what we refer to as VOCs – volatile
organic compounds, which come from
cleaning products and just about every
manmade product. When these pollut-
ants are allowed to accumulate in a sealed
environment they can become a potentially
serious issue. By reducing the amount of air
changes in our homes as a result of weather
sealing, we have in effect created an envi-
ronment for the accumulation of indoor
pollutants.
Some of the measures that can be taken
to address this issue are:
• Source control. Identify the source
and eliminate or modify. Direct vented
heating appliances are a great example
as they eliminate the problem of reverse
flow of combustion products created by
negative pressure.
• Air Filters. Point-of-use air cleaners
are growing in popularity, while whole
house filters such as those used in
furnaces and air handlers now achieve
MERV ratings of 13. The one-inch filter
that we most often see has a MERV
rating of between 1 and 4, which is
less than 20 percent efficient. HEPA
filters used in hospitals are over 90
percent efficient. Be sure to check with
Mechanical Solutions Can Improve Indoor Air
Make-up air systems provide the fresh air that tightly sealed homes lack
By Bruce Marshall, Emerson Swan
