BPI Building Analyst Field Exam Blower
Door
What is a Blower Door? - correct answer ✔- a diagnostic tool designed to
measure the airtightness of building and to help locate air leakage sites.
- the fan blows air into or out of the building to create a slight pressure
difference between inside and outside.
- this pressure difference forces air through all holes and penetrations in the
exterior envelope
- the tighter the building (eg. fewer holes), the less air you need from the
blower door fan to create a change in building pressure
- problem spots are easier to find using chemical smoke, an infrared camera
or simply feeling with your hand.
- it can also help you access the potential for backdrafting of natural draft
combustion appliances by exhaust fans and other mechanical devices
- help to determine the need for mechanical ventilation in the house
Basic dynamics of air leakage in buildings - correct answer ✔- for air leakage
(infiltration or exfiltration) to occur, there must be both a hole or crack, and a
driving force (pressure difference) to push the air through the hole.
Five most common driving forces which operate in buildings are: - correct
answer ✔1) STACK EFFECT - warm air rises due to buoyancy & leak out the
top of the building and replaced by colder outside air entering the bottom of
the building. (winter time)
(Reverse stack effect is summer time only)
2) WIND PRESSURE EFFECT - exposed areas will have wind go right it
3) POINT SOURCE EXHAUST OR SUPPLY DEVICES - chimneys for
combustion appliance and exhaust fans push air out of the building when they
are operating
Door
What is a Blower Door? - correct answer ✔- a diagnostic tool designed to
measure the airtightness of building and to help locate air leakage sites.
- the fan blows air into or out of the building to create a slight pressure
difference between inside and outside.
- this pressure difference forces air through all holes and penetrations in the
exterior envelope
- the tighter the building (eg. fewer holes), the less air you need from the
blower door fan to create a change in building pressure
- problem spots are easier to find using chemical smoke, an infrared camera
or simply feeling with your hand.
- it can also help you access the potential for backdrafting of natural draft
combustion appliances by exhaust fans and other mechanical devices
- help to determine the need for mechanical ventilation in the house
Basic dynamics of air leakage in buildings - correct answer ✔- for air leakage
(infiltration or exfiltration) to occur, there must be both a hole or crack, and a
driving force (pressure difference) to push the air through the hole.
Five most common driving forces which operate in buildings are: - correct
answer ✔1) STACK EFFECT - warm air rises due to buoyancy & leak out the
top of the building and replaced by colder outside air entering the bottom of
the building. (winter time)
(Reverse stack effect is summer time only)
2) WIND PRESSURE EFFECT - exposed areas will have wind go right it
3) POINT SOURCE EXHAUST OR SUPPLY DEVICES - chimneys for
combustion appliance and exhaust fans push air out of the building when they
are operating
