With the advent of a more energy conscious consumer, builders
are spending hundreds to thousands of dollars providing new
homes with latest and greatest energy efficient features.
However, recent studies have shown that for mere pennies on
the dollar, builders can substantially increase the overall
efficiency of new homes by simply tightening ductwork
Leaky ductwork often accounts for 10 to 30 percent of total
heating and cooling costs. If duct leakage is 20% of total
airflow, the efficiency of the cooling system can drop as much
as 50%. Duct leakage also lowers heating and cooling capacity
thereby reducing equipment life. And while the increase in
energy costs as a result of leaky ducts can be significant,
protecting the health and safety of the building occupant is
the most important reason to insist on a tight duct
Air leaking into or out of the HVAC system can dramatically
affect humidity control, condensation potential, indoor air
quality, energy consumption, and occupant comfort.
Air leaks on the return side of the HVAC system can cause the
home to become pressurized because more air is being supplied
to the home than is being removed by the return air ducts.
Pressurization can lead to dust filtration and wasted energy
costs. The HVAC system is the primary source of
dehumidification during warm weather. Leaks in ductwork on the
return air side of the unit that are outside the thermal
envelope can pull hot, humid air from the attic into the HVAC
system. This can cause a burden on the systemís ability to
dehumidify and cool the air in the home.
Air leaks on the supply side of the HVAC system can cause the
home to become depressurized because less air is being supplied
to the home than is being removed by the return air ducts (see
diagram). Depressurization can pull dust, pollen, mold spores,
carbon monoxide from cars, and other contaminants into the home
through any air leaks in the building envelope. Depressurization
can also pull air down through chimney flues and vent pipes of
combustible appliances at a rate that can cause the pilot flame
to be extinguished. If this occurs, natural gas or combustion
byproducts can be pulled into the home. The depressurization
caused by supply air duct leakage pumps conditioned air out of
the system causing significant loss of energy.
Airtight duct construction is one of the keys to providing a
quality heating and cooling system. Such systems assist in
making the homeís environment more healthy and comfortable and
lead to greater energy efficiency.
There is only one way to make sure that ductwork has been
thoroughly sealed... TEST IT. A simple pressure test can
measure the airtightness of the air distribution system and
helps hold installers to a high standard of quality.
Pressure testing is not a new concept in home construction.
Plumbers have their work pressure tested on every job, and the
test forces them to get it right, meaning NO leaks. But when
plumbing leaks there is an immediate consequence... things get
wet. Air leakage on the other hand seldom causes immediate
trouble. Instead, homeowners gradually become aware of comfort
problems, high utility bills and decreasing indoor air quality
over time. A duct tightness test is the only way to identify
defects in advance.
Qualified Inspection Services through its affiliate company
Energy Smart can provide third party residential inspection and
testing services designed to help builders construct more
energy efficient homes. To find out how our services may benefit
your company, please contact us today.