Home Energy Losses: Air Leakage and Air Sealing
Air Leakage and Energy Losses
Many houses, in particular the older ones, tend to be very
leaky. And this can cost highly: according to EPA studies, in a
typical American house air leakage accounts for between 25
percent and 40 percent of the energy used for heating and
cooling.
Air leakage is indeed a cause of higher energy bills, low
comfort, moisture, cold drafts, unwanted noise and lower indoor
air quality or lower building durability. And air sealing one
of the most crucial elements of an energy efficient building.
Sealing all horizontal and vertical construction joints
should be considered a common practice in home building.
See also:
Windows and doors
Weatherstripping
Windows and doors Caulking
Air
Leakage Tests in existing homes
Leakage tests may be important when remodeling. Tests will help
you decide the right approach concerning key factors as windows
replacement, duct improvements or walls insulation. Tests will
also help you on decisions concerning new heating or cooling
equipment.
So, consider an air leakage test. They are cheap, quick (usually
performed in a few hours time: 2-4 hours) and very common. They
are based in «blower doors» and «duct blowers» equipment, and
allow to measure the leakiness of buildings and ductwork and to
locate the source of leaks.
New
Houses Air Sealing
Many air leakage paths are difficult and costly to access and
properly seal in existing homes.
So, if building a house, consider including the right air
sealing. With a minimal investment, you will save energy and
increase comfort and air quality…
Air Leakage Paths
Air leakage typically occurs at several common locations,
namely:
- joints between building materials
- gaps around doors and windows frames
- bottom of walls, in the joints with the floor/foundation
- penetration linked to piping, ducts...
- attic penetrations: in the ceiling plane, and in ducts holes,
pipes and chimneys joints.
These last paths involve the most important air-sealing
areas, because these air leakage sources tend to be relatively
large and because the hot air tends to rise and to flow to the
top of the house, escaping by it whenever possible. Air sealing
windows and door is a good practice, but sealing attic
penetrations is usually the most important feature of home air
sealing.
Materials used in Air Sealing
There are many products available in the market for air sealing.
They include caulks, expanding foams, weather-stripping,
gaskets, door sweeps... Densely installed insulation is also an
effective way of reducing air leakage through walls and
ceilings, while polyethylene can be installed as an air and
vapor barrier.
Air leakage and mechanical ventilation
Air sealing your house is undoubtedly one of the most effective
ways to save energy, but airtight homes need also adequate
ventilation, and that means mechanical ventilation in most
climates and days to maintain good indoor air quality.
Homes need minimum amounts of air exchange in order to provide
oxygen for their residents, to control humidity, to eliminate
odors, and so on. And very few homes have the ability to truly
control ventilation rates. In some cases and when the weather is
favorable, you may open the windows or profit from natural
ventilation. But in most homes and weather conditions, houses
that are tightly sealed demand active ventilation - exhaust
fans, heat recovery ventilators… - to ensure that fresh air is
provided. In cold climates, and in houses without a good natural
ventilation, if you have implemented an highly sealed approach
to your home, you should talk with your heating/cooling
contractor about installing an energy recovery ventilation
system. It is essential to regulate fresh air entries, humidity
and minimize energy losses.
See also:
Energy Efficient House Basics
Good and
bad
Indoor Air quality
Mechanical ventilation: HEV and HRV
Natural
Ventilation: cross and stack
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