Francis R. Lazaro - As a NJ certified Energy Auditor/Inspector for fifteen years, my job was to inform and educate home energy users on saving and conservation. There seems be some confusion about the difference between Energy Conservation and Energy Efficiency. The following is my take on this subject.
Energy, Wildlife, Forrest, etc. conservationists all has a
common goal. That is to “Sustain a Healthy Environment”. Sometimes they are viewed
as separate and completely different entities. They all have the same goal but
energy conservationists because of commercial, institutional and residential
usage it deals a lot with “Sustaining a Healthy Indoor Environment”.
Energy Efficiency differs from energy conservation is that
efficiency deals primarily with costs. While energy usage of an appliance or
application plays a major role with the costs of operation; the inclusion of
the purchase price, costs of installation and durability determines if it is
efficient. There is a Cardinal rule with Energy Efficiency, “If it ain’t broke,
don’t fix it!”
The role of an energy conservationist becomes confusing or
misleading to people when installing or applying energy efficient measures in a
structure. They assume energy efficiency is the same as energy conservation.
The easiest way for me to explain this to you is to compare an energy efficient
home to one that is not from an energy conservationist’s perspective.
Let’s assume there are two identical houses, same age, size
and number of occupants. House “A” has a 30% lower energy bill than house “B”.
This was due to the improvements house A did, such as adding more insulation in
the attic, replacing the heating system with an efficient one and replacing all
the windows in the house with thermal pane windows. This explicitly implies
that house A uses 30% less energy than house B to heat their homes. However,
house B may have better indoor air quality than house A.
There are several factors one has to consider involving the
aforementioned. One is what happens to air inside a house when heated or
cooled. When air is heated the molecules become excited and move away from each
other (expansion) and when cooled or losing temperature the molecules become
less excited and move closer together (contraction). Another factor is the
volume of air within the house that remains constant. In other words if you
pour 10 ounces of water into an eight ounce glass the amount of water inside
the glass is eight ounces, the other two ounces overflows the rim of the glass.
If we apply this to a house, when the heat comes on the air
inside the house expand and since the volume of air inside the house is
constant the expansion pushes air out the house. This takes humidity and other
pollutants found inside the house with it. As the temperature of the air inside
the house drop the air contracts which brings in fresh air from outside. This
is known as “Air Exchange” and heating one’s home is the primary source of it
during the heating season. While the efficient heat system installed in house A
may account for some of the reduction in energy costs, it probably accounts for
a small portion of it. Which means house B heating system comes on more
frequently than house A and has more air exchange than house A. This doesn’t
mean that house A has a lesser air quality than house B. It does mean that
house A has a higher probability to have an indoor air quality problem than
house B. This is what concerns energy conservationists. Most of us believe in
“Murphy’s Law”.
Clearly all of the aforementioned is an oversimplification
in our pursuit to achieve a “Sustainable Healthy Indoor Environment”. Factors
like type of heating systems, number of gas appliances, fireplaces, exhaust
fans, occupants’ behavior, area climatic conditions, site drainage and more
were not discussed here but do play a very important role in achieving our
goal. It is good to note that the average homeowner is unlikely to cause an
indoor air quality problem by making energy efficient measures in their homes.
Companies that “Air Seal” structures can cause an indoor air quality problem.
What these companies do is first determine the “Minimum Ventilation
Requirements” then measure (before air sealing) the air exchange. This
determines if they can proceed with air sealing the structure. Afterwards they
verify the air exchange to assure they did not violate the Minimum Ventilation
Requirements for the structure.
The role of an energy conservationist is to encourage the
use of Energy Efficient measures with a deep concern for the health and
well-being of the occupants as well as the integrity of the structure. Two
topics for those who wish to know more about this topic are “Combustion
Appliance Zones” (CAZ) and “Sick Building Syndrome” (SBS).
