1 | weatherization assistance program standardized curriculum – july 2012eere.energy.gov...

1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012 eere.energy.gov

Identifying and Air Sealing the Building Envelope

WEATHERIZATION INSTALLER/TECHNICAN FUNDAMENTALS

WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012


IDENTIFYING & AIR SEALING THE BUILDING ENVELOPE

Learning Objectives

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)



Learning Objectives

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.


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.

Comfort, Safety and Efficiency



Typical Air-Leakage

Image courtesy of ENERGY STAR



Primary Air Infiltration Sites

Data courtesy of the California Energy Commission

5% Fans and vents

12% Windows

13% Doors

15% Plumbing penetrations

Fireplaces 16%

Electrical outlets 2%

Floors, walls, and ceilings 36%



Check typical hot spots• Flues and plumbing vents

• Wire pathways

• Recessed fixtures (lights and fans)

• Chimney penetrations

Signals• Blower door, smoke• Dirty or discolored insulation

Finding Air Leaks

Photos courtesy of the US Department of Energy




Thermal Boundaries & Air Barriers

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


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%.

The Thermal Boundary


Graphic courtesy of Dr. Energy Savers


Thermal Boundaries are Obvious

Photo courtesy of the US Department of Energy



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.

Air Barrier





Thermal Boundaries & Air Barriers

Thermal Boundary

Air Barrier

An uninsulated attic hatch is a gap in the attic’s thermal boundary.



PRESSURE & THERMAL BOUNDARIES

Photo courtesy of NRCERT



Air Barrier

A mechanical chase containing ducts can break the attic’s air barrier.

Thermal Boundary

Air Barrier




Moisture

Thermal Boundary

Air Barrier

Moisture flows with warm air through breaks in the air barrier, causing damage when it condenses on cool surfaces.



Other construction details can result in gaps in pressure and thermal barriers.

•Changes in ceiling height

•Knee-wall attics

•Walk-up attics

Construction Details

• Dropped soffits

o Above kitchen cabinets

o In bathrooms

o Above vanities

o Above built-ins

o At duct chases/bulkheads



Changes in Ceiling Height

ConditionedSpace

ConditionedSpace

Attic

Not only is the top of the wall uninsulated...Not only is the top of the wall uninsulated...


Graphic courtesy of Anthony Cox



The interior wall cavities act as a chimney that robs

the house of heat and conditioned air.

The interior wall cavities act as a chimney that robs

the house of heat and conditioned air.


Graphics courtesy of Anthony Cox



Open Wall Cavity




Knee-Wall Attics

Main Attic

Knee-wall Attic

Open Wall CavitiesOpen Wall Cavities




Dropped Soffits

Kitchen wall cabinets mounted

under soffit or valance

Kitchen wall cabinets mounted

under soffit or valance




Dropped Soffits

Attic insulation can hide dropped soffits.Attic insulation can

hide dropped soffits.




Dropped Soffits

If you see soffit-mounted cabinets,

remember to investigate during

attic inspection.

If you see soffit-mounted cabinets,

remember to investigate during

attic inspection.




Vent pipe for kitchen exhaust fan helps locate area over kitchen cabinets.

Vent pipe for kitchen exhaust fan helps locate area over kitchen cabinets.



Open Wall Cavities

A closer look reveals a dropped soffit and

misaligned pressure and thermal boundaries.

A closer look reveals a dropped soffit and

misaligned pressure and thermal boundaries.

Photo Source: US Department of Energy



Where Is the Air Barrier?

Cape Cod1½ Story House





Targeted air sealing defines air barrier





Pressure and thermalboundaries now aligned



Plumbing pipe and dirty insulation are clues…

Plumbing pipe and dirty insulation are clues…

…that an attic bypass is allowing air flow through the

insulation.

…that an attic bypass is allowing air flow through the

insulation.



An innocent looking fireplace and built-in

china cabinet…

An innocent looking fireplace and built-in

china cabinet…



…hides an attic bypass you can park a car in.

…hides an attic bypass you can park a car in.

The client wondered why her silverware got

cold in the winter.

The client wondered why her silverware got

cold in the winter.



Gaps ≤ 1/4”Caulk

General Guidelines

Energy Blast ServicesThe Daily Green

Gaps 1/4” – 3”Spray foam

OtherFoam board, fiberglass in

plastic bags, etc.


US Dept. of Energy


Sometimes sealing air leaks requires repairing damaged drywall.

Drywall Repair




The hole is capped at the level of the attic floor and sealed with

the two-part foam.

The hole is capped at the level of the attic floor and sealed with

the two-part foam.

Shielding prevents blown-in cellulose insulation from touching the chimney.

Shielding prevents blown-in cellulose insulation from touching the chimney.




In older homes the ceiling level changes in closets, causing

gaps in the pressure and thermal boundaries.

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.

The uninsulated bedroom and bathroom walls are

exposed to outdoor temperatures.





New insulation will be blown over the repaired pressure boundary and the existing

insulation.

New insulation will be blown over the repaired pressure boundary and the existing

insulation.

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.

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.




The pressure and thermal boundaries are now

continuous and in contact with each other.

The pressure and thermal boundaries are now

continuous and in contact with each other.



Walk-Up Attics

Where Is the Pressure Boundary? Where Should It Be?




If the client does not use the attic often:

Walk-Up Attics

• 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.

It is also cheaper and faster than the alternative.




If the client uses the attic fairly often:

Walk-Up Attics

• 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.




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.

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.



The door is insulated and weather-stripped.The door is insulated and weather-stripped.



The final step in aligning the pressure and thermal boundaries is to insulate and air seal the stairs.

The final step in aligning the pressure and thermal boundaries is to insulate and air seal the stairs.



The spray foam must be covered since it is located

within the living space.

The spray foam must be covered since it is located

within the living space.



Summary

• 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.


1 | weatherization assistance program standardized curriculum – july 2012eere.energy.gov...

Documents

building envelope air

air barrier limits air

attics air barrier

slide slide

terms of air barrier

building envelope slide

common air sealing materials

wellsealed air barrier