Transcript WEATHERIZATION INSTALLER/TECHNICAN FUNDAMENTALS Identifying and Air Sealing the Building Envelope WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012 1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM.

WEATHERIZATION INSTALLER/TECHNICAN FUNDAMENTALS
Identifying and Air Sealing the
Building Envelope
WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012
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ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012
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Learning Objectives
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
By attending this session, participants will be able to:
• Differentiate between the thermal and pressure boundaries and
describe the behavior and function of each.
• Summarize basic principles of air leakage.
• Identify the proper location of the pressure and thermal
boundaries.
• Identify common sites and signals of breaks in the pressure
and thermal boundaries.
• Identify common air sealing materials and their characteristics.
(continued on next slide)
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Learning Objectives
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
By attending this session, participants will be able to:
• Explain what is meant by “inside” and “outside” in terms of air
barrier and how a blower door is used to determine that.
• Identify typical construction details that lead to gaps in
pressure and thermal boundaries and know how to treat them.
• Describe treatment options for walk-up attics.
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Comfort, Safety and Efficiency
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
A comfortable, safe, and energy-efficient home
requires:
• A fully insulated thermal envelope or thermal boundary.
• A well-sealed air barrier.
• Continuous thermal boundaries and air barriers that are in
contact with one another.
• Efficient, properly sized equipment to condition the living
space and heat water.
• A well-designed and balanced air distribution system.
• Healthy indoor air quality.
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Typical Air-Leakage
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Image courtesy of ENERGY STAR
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Primary Air Infiltration Sites
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
5% Fans and vents
12% Windows
Floors, walls, and
ceilings 36%
13% Doors
Electrical outlets 2%
15%
Plumbing penetrations
Fireplaces 16%
Data courtesy of the California Energy Commission
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Finding Air Leaks
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Check typical hot spots
• Flues and plumbing vents
• Wire pathways
• Recessed fixtures
(lights and fans)
• Chimney penetrations
Signals
Photos courtesy of the US Department of Energy
• Blower door, smoke
• Dirty or discolored insulation
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Thermal Boundaries & Air Barriers
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
For maximum efficiency and comfort,
the thermal boundaries and air barriers must
be continuous and in contact with each other.
Graphic developed for the US DOE WAP
Standardized Curricula
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The Thermal Boundary
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The Thermal Boundary
• Limits heat flow between inside and outside.
• Is easily identifiable by presence of insulation.
The location of insulation in relation to other building
components is critical to its effectiveness.
• Even small areas of
missing insulation are
very important.
• Voids of 7% can
reduce effective R-value
by almost 50%.
Graphic courtesy of Dr. Energy Savers
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Thermal Boundaries are Obvious
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Photo courtesy of the US Department of Energy
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Air Barrier
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Air Barrier
• Limits air flow between inside and outside.
• Is more difficult to identify.
• Is not always where you think it is.
A blower door is used to locate
the air barrier.
Graphic developed for the US DOE WAP
Standardized Curricula
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Thermal Boundaries & Air Barriers
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
An uninsulated attic
hatch is a gap in the
attic’s thermal boundary.
Air Barrier
Thermal Boundary
Graphic developed for the US DOE WAP Standardized Curricula
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PRESSURE & THERMAL BOUNDARIES
Photo courtesy of NRCERT
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Air Barrier
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
A mechanical chase
containing ducts can
break the attic’s
air barrier.
Air Barrier
Thermal Boundary
Graphic developed for the US DOE WAP Standardized Curricula
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Moisture
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Moisture flows with warm
air through breaks in the
air barrier, causing damage
when it condenses on
cool surfaces.
Air Barrier
Thermal Boundary
Graphic developed for the US DOE WAP Standardized Curricula
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PRESSURE & THERMAL BOUNDARIES
Photo courtesy of NRCERT
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PRESSURE & THERMAL BOUNDARIES
Photo courtesy of NRCERT
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PRESSURE & THERMAL BOUNDARIES
Photo courtesy of NRCERT
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PRESSURE & THERMAL BOUNDARIES
Photo courtesy of NRCERT
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Construction Details
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Other construction details can result in gaps in
pressure and thermal barriers.
• Changes in
ceiling height
• Knee-wall attics
• Walk-up attics
• Dropped soffits
o Above kitchen cabinets
o In bathrooms
o Above vanities
o Above built-ins
o At duct chases/bulkheads
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Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Attic
Not only is the top of
the wall uninsulated...
Conditioned
Space
Conditioned
Space
Graphic courtesy of Anthony Cox
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Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The interior wall cavities
act as a chimney that robs
the house of heat and
conditioned air.
Graphics courtesy of Anthony Cox
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Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Open Wall Cavity
Photo courtesy of the US Department of Energy
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Knee-Wall Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Main Attic
Open Wall Cavities
Knee-wall Attic
Graphic courtesy of Anthony Cox
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Dropped Soffits
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Kitchen wall
cabinets mounted
under soffit or
valance
Graphic courtesy of Anthony Cox
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Dropped Soffits
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Attic insulation can
hide dropped soffits.
Graphic courtesy of Anthony Cox
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Photo courtesy of NRCERT
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Dropped Soffits
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If you see soffitmounted cabinets,
remember to
investigate during
attic inspection.
Graphic courtesy of Anthony Cox
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Vent pipe for kitchen
exhaust fan helps
locate area over
kitchen cabinets.
Photo courtesy of the US Department of Energy
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A closer look reveals
a dropped soffit and
misaligned pressure and
thermal boundaries.
Open Wall
Cavities
Photo Source: US Department of Energy
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Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Cape Cod
1½ Story House
Graphic developed for the US DOE WAP Standardized Curricula
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Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Targeted air sealing
defines air barrier
Graphic developed for the US DOE WAP Standardized Curricula
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Where Is the Air Barrier?
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Pressure and thermal
boundaries now aligned
Graphic developed for the US DOE WAP Standardized Curricula
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Plumbing pipe and dirty
insulation are clues…
…that an attic bypass is
allowing air flow through the
insulation.
Photos courtesy of the US Department of Energy
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An innocent looking
fireplace and built-in
china cabinet…
Photo courtesy of the US Department of Energy
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…hides an attic bypass you
can park a car in.
The client wondered
why her silverware got
cold in the winter.
Photo courtesy of the US Department of Energy
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General Guidelines
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Energy Blast Services
US Dept. of Energy
Gaps ≤ 1/4”
Gaps 1/4” – 3”
Other
Caulk
Spray foam
Foam board,
fiberglass in plastic
bags, etc.
The Daily Green
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Drywall Repair
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Sometimes sealing air
leaks requires repairing
damaged drywall.
Photos courtesy of the US Department of Energy
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Shielding prevents blown-in
cellulose insulation from
touching the chimney.
The hole is capped
at the level of the attic
floor and sealed with
the two-part foam.
Photo courtesy of the US Department of Energy
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Photo courtesy of the US Department of Energy
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Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
In older homes the ceiling level
changes in closets, causing
gaps in the pressure and
thermal boundaries.
The uninsulated bedroom
and bathroom walls are
exposed to outdoor
temperatures.
Photo courtesy of the US Department of Energy
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Changes in Ceiling Height
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
The pressure boundary is
re-established by capping
the hole with foam board at the
same level as the rest of the
attic and air sealing.
New insulation will be blown
over the repaired pressure
boundary and the existing
insulation.
Photo courtesy of the US Department of Energy
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The pressure and thermal
boundaries are now
continuous and in contact
with each other.
Photo courtesy of the US Department of Energy
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Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
Where Is the Pressure Boundary?
Where Should It Be?
Graphic developed for the US DOE WAP Standardized Curricula
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Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If the client does not
use the attic often:
• An insulated, airtight cover can
be installed on top of the
stairwell.
• The pressure and thermal
boundaries are aligned at
the level of the attic floor.
This approach brings the stairwell
into the conditioned space.
Graphic developed for the US DOE WAP Standardized Curricula
It is also cheaper and faster than
the alternative.
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Walk-Up Attics
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
If the client uses the
attic fairly often:
• The pressure and
thermal boundaries
must be established at
the stairs, stairwell
walls, and door to the
attic stairs.
• This approach leaves
the stairwell open to the
attic and outside the
conditioned space.
Graphic developed for the US DOE WAP Standardized Curricula
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Since these attic stairs were
used often, it was better for
the client to keep the
stairwell “outside,” which
means dense-packing the
stairwell walls with
insulation.
Photo courtesy of the US Department of Energy
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Photo courtesy of the US Department of Energy
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The door is insulated
and weather-stripped.
Photo courtesy of the US Department of Energy
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The final step in aligning
the pressure and thermal
boundaries is to insulate
and air seal the stairs.
Photo courtesy of the US Department of Energy
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The spray foam must be
covered since it is located
within the living space.
Photo courtesy of the US Department of Energy
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Summary
IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE
• For maximum efficiency and comfort, the thermal and pressure
boundaries must be continuous and in contact with one another.
• Electrical and mechanical chases, missing top plates,
knee walls, dropped soffits, and changes in ceiling height are
common trouble spots.
• Targeted air sealing defines the pressure boundary.
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