What is Depressurization and why should I be concerned?
We're glad you asked!
Depressurization can pose a threat to your family's health and
safety. The latest in-home research conducted in Manitoba has
proven that levels of depressurization occurring in new and older
homes, is potentially a serious safety issue that remains unresolved.
What is Depressurization?
Depressurization is a condition that is created when air within
the home is exhausted by natural or mechanical means. As air within
the home is being removed, pressure levels in the home are lowered.
This lowering of air pressure within the home increases air leakage
into the home around doors, windows and other cracks in the building
envelope. When building pressure is reduced, the least restrictive
way in which to bring air back into the home is via the chimney
and that is typically what happens. Air is drawn back down the
chimney allowing the products of combustion to enter the home.
This can create a very hazardous condition that has the potential
to cause serious injury and even death in cases where carbon monoxide
(CO) is being produced.
What research has been done to confirm that this is a
serious issue and concern?
Research in Manitoba has shown that the present codes, standards
and inspection methods have fallen short. Even though installations
follow the codes and standards, and are inspected by the authorities,
at present this does not guarantee that a home will not experience
a serious depressurization condition. There are no requirements
or enforcement to conduct a depressurization test when servicing,
maintaining, installing or replacing a piece of equipment. Some
homes in Manitoba have been shown to have depressurization levels
well in excess of 20 Pascalšs (pa) -5 pa. = 0.02" water column
(wc).
What are the causes of Depressurization?
If you have exhaust devices (central vacuum systems, bathroom
fans, dryers, kitchen range fans or any other exhaust devices)
that remove air from the home there is a greater potential for
a problem. Depressurization can also be a problem in homes that
have high, large, or multiple chimneys. The reason is that these
types of chimneys create high negative draft conditions that will
pull more air from within the home, which again has been proven
in actual tests to be a serious problem.
How do I know if my home has a Depressurization problem?
Testing can be done to determine the level of depressurization
and once determined remedial measures if required can be proposed.
The testing does not take long to complete and is relatively inexpensive.
Remember that if you are planning to replace an appliance or add
an exhaust device to the home, have the test done prior to the
start of any work.
How come my regular technician who has been servicing
our equipment did not tell me about Depressurization or that my
home had a problem?
In the past, all technicians were taught they need only concern
themselves with energy efficient, new homes, as it was believed
that these homes had depressurization problems. Research conducted
specifically since 1997, has proven that a home of any age and
style can have and experience serious depressurization conditions.
With no testing standard in place or training there was no way
for any technician to know for certain whether or not there is
a depressurization problem with a home when performing a service
for the homeowner by simply looking at the home.
My home is not air tight. In fact, it's very leaky.
Almost every homeowner says his or her home is not airtight and
therefore is not a problem. This is just not the case the actual
in-home research proves that. Just like you need to know about
the signs and dangers of carbon monoxide you need to educate yourself
about depressurization and how the two are inter-related.
CO and depressurization are similar in that you cannot detect
or identify a problem without the proper testing equipment. As
of October 1, 2000 over 600 homes that were tested in Manitoba,
25% or 1 out of 5 homes tested, exceeded the 5 pa. limit set
out in the codes. Real eye openers for all those homeowners who
think their homes are leaky.
What can be done to reduce the potential for Depressurization?
Homeowners should have a depressurization test conducted in addition
to or as part of the Federal Governments Office of Energy Efficiency,
EnerGuide for Houses, energy evaluation program. This evaluation
will identify any potential safety issues that could your family.
Independent trained and qualified energy inspectors perform these
in-home energy evaluations.
In addition, homeowners who are planning to install an exhaust
device or retrofit their homes building envelope regardless of
how minor it may seem, should consult with a Heating Refrigerating
and Air Conditioning Institute of Canada (HRAI) certified residential
mechanical ventilation designer and installer. Having been trained
to Nationally recognized standards and undergoing training updates
these technicians remain current with changes as they occur.
Return to the FAQ Index
