This document discusses the importance of air tightness in buildings. It defines key terms like infiltration, exfiltration, and building envelope. Having an air tight building envelope can improve energy efficiency and occupant comfort by reducing air leakage. Leaky buildings can increase energy costs and accelerate issues like mold growth. The document recommends methods for improving air tightness during design, construction, and testing, such as using air tight materials and sealing openings and penetrations.
2. Overview
Terminologies.
Benefits of AirTight Buildings
Airtightness consequences.
Improving Airtightness
Air tightness test.
3. Controlling air leakage is an important factor
effecting:
Building's energy efficiency.
Occupants comfort.
Uncontrolled Infiltration of air could have drawbacks
such as
Increasing energy consumption.
Health and safety of the buildings occupants.
Accelerate deterioration of building materials.
Such as concrete corrosion, mold, wet insulationetc.
4. Airtightness
Resistance of infiltration/exfiltration of conditioned air through
gaps, cracks, openings in the building envelop.
Causes of air leaks
Pressures difference across the building envelope.
Temperature difference across the building envelope.
5. Air Leakage
Air leakage refers to the unplanned, unpredictable and
unintentional airflow in the buildings (Infiltration) or out of
the buildings (exfiltration) through buildings envelope.
Building Envelope
The building envelope includes all the building components
that separate the indoors from the outdoors.
It includes
o Foundation
o Roof
o Windows
o Exterior walls
o doors.
6. Infiltration
is the movement of air through leaks, cracks, or other
adventitious openings INTO the building.
Exfiltration
is the movement of air through leaks, cracks, or other
adventitious openings OUTSIDE the building.
Wind Washing
Air movement that occurs due to wind entering a building
envelop and passing through the thermal insulation and
significantly impacting the thermal and moisture
performance of those assemblies.
7. Stack Effect
Stack effect is a temperature-driven phenomenon, which is
especially noticeable in cold weather, when warmer indoor air,
which is lighter than the colder outdoor air, tends to rise in the
building.
It is influenced by:
Temperature differential between indoors and outdoors.
Size and location of the opening in the building enclosure.
9. Air-tight buildings waste less energy, and cause less
CO2
Enables right-sizing of HVAC system.
Reduced Energy Costs.
Vital to achieving passive builds
Reduced Interstitial Condensation
More Comfort for Occupants.
Opportunity for Owners to give their buildings an
advantage.
13. Design a tight building.
Material type.
Building orientation.
Opening sizes.
Install airtight layer.
Pressurization.
Construct a tight building.
Pipe and duct penetrations.
Openings sealant.
Walls joints.
Use sealant for openings and penetrations.
19. Passive House
Is the house which is built to be extremely
energy efficient, and has a comfortable
interior climate maintained without a
traditional heating system - or active cooling.
20. Convective loops can form within
highly air permeable insulation
(low-density fibrous insulations)
or small gaps around insulation.