THE IMPORTANCE OF YOUR HOUSE "ENVELOPE"
Your household heating and cooling
system's equipment is only part of the equation. The efficiency of the
building envelope (outer walls, floor, ceiling, and roof) also requires
attention. A heating and air conditioning system provides heating and
cooling and the house uses (or wastes) it, in exact balance.
Professional energy auditors use blower
door tests to help determine a home's airtightness.
These are some reasons for establishing
the proper building tightness:
-
Reducing energy consumption due to air leakage
-
Avoiding moisture condensation problems
-
Avoiding uncomfortable drafts caused by cold air in
the winter and hot, humid air in the summer leaking in from
the outdoors
-
Making sure that the home's air quality is not
contaminated by indoor air pollution.
How They Work
A blower door is a powerful fan that
mounts into the frame of an exterior door. The fan pulls air out of the
house, lowering the air pressure inside. The higher outside air
pressure then flows in through all unsealed cracks and openings. The
auditors may use a smoke pencil to detect air leaks. These tests
determine the air infiltration rate of a building.
AIR LEAKS VS. INSULATION
To increase the economy of heating and
cooling, most homeowners automatically assume that insulation is the
answer. However, insulation is not the whole story. Actually, in most
homes air leakage is the biggest robber of heating and air
conditioning dollars.
Houses leak air because of the difference
between indoor and outdoor air pressure. Imagine your house as a hot
air balloon. The biggest pressure differences are high and low in a
building. Holes in these areas typically leak more air than the holes
in the middle. Warm air rises and leaks out any unsealed areas at
the top of the building. Leaks inward tend to be at the bottom of the
structure, pulling in cool air in the winter and hot, humid air in the
summer. This can cause your home to have humidity control problems,
causing mold and mildew problems, and high utility bills.
"Airtight" homes are more economical and
more comfortable to occupy, if proper ventilation is provided. There
are no drafts, only controlled air flow. They are also more durable,
too.
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