Auto-Sealing New Home Leaks with Aerosols

Curtis Harrington, PEUC Davis, Western Cooling Efficiency Center

EEBA High Performance Home Summit:October 17, 2018

Presentation Overview

»Air Sealing Benefits

»Basic Concept

»Development Timeline

»Building America Project

»Path Forward

»AeroBarrier Update

Energy Benefits of Air Sealing

»Heating and cooling is responsible for large fraction of energy use• 48% in residential

• 35% in commercial

» Infiltration is responsible for 30% of the heating and cooling load

»Better insulated envelopes increase fraction of heating & cooling associated with infiltration/ventilation

» Envelope tightness standards were fairly recently included in U.S. codes

»Cost-effective approaches to sealing envelope leakage would improve and simplify adherence to code

Health Benefits of Air Sealing

»Better control of air flow and reduced infiltration of outdoor air and outdoor pollutants (e.g. PM 2.5 or Ozone)

»Facilitates use of Mechanical Ventilation• HRV or ERV and filters• Putting HRV/ERV on leaky building doesn’t save

energy or reduce uncontrolled infiltration

Health Benefits of Air Sealing (Large Buildings)»NIST measurements of large building leakage suggest that

more air is needed for pressurization than for ventilation

»Better and more efficient air flow control in sensitive spaces

• Elimination of outdoor chemical infiltration

• Contagious disease spaces

• Clean rooms

• Laboratories

• Schools in non-compliance areas (have current CEC project on HVAC and IAQ in schools)

Health Benefits of Air Sealing (Large Buildings)»Reduce noise transfer

»Reduce smell transfer

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Basic Concept

Seal formed between gap in foam

Blower door setup for pressurization

Building America Project Goals

Integrate aerosol sealing into building process»Determine appropriate time for applying

»Measure performance relative to conventional methods

»Determine existing sealing efforts that could be avoided

»Determine cost-effectiveness

Building America Project Team

»Project Partners: • Center for Energy and Environment • Building Knowledge Inc.• University of Minnesota’s Cold Climate Housing

Program• Aeroseal LLC

»Builders:• Two in California• Two in Minnesota

Building America Project ApproachHouse

Leakage Assessment

• Review existing sealing practices

• Aerosol sealing demonstration

Develop Two Sealing

Options

• Meet with builder to go over options

• Pick two promising approaches

Perform Aerosol Sealing

• Seal at least two homes under each option

• Evaluate impact relative to baseline

Refine Sealing Options

• Refine most promising option

Perform Aerosol Sealing

• Seal 3-4 homes under refined option

Building America Interim Results (CA)»California Builder #1

»Homes designed with sealed attics

»Using open-cell spray foam• Under roof deck

• At rim joist and other mechanical penetrations

»Fiberglass/mineral wool in wall cavity

»HRV integrated into central air handler

»Target leakage of 800 CFM50 (2.1-2.4 ACH50)

Conventional Sealing

Can foam at seams where wood is joined

Can foam and gasket at sill plate

Foam gasket to seal drywall to top plate

Sealing Options

»Sealing options• Option 1: After open-cell spray foam

• Option 2: Before spray foam insulation

»Advantage of sealing before drywall• Addresses outer wall surface

• Seals less prone to damage in wall cavity

• Easier aerosol distribution

Option 1: After Foam

Foam at roof deck

Foam at rim joist

Results Sealing After Foam

Stage/Option Lot PlanFloor Area

(ft2)Volume

(ft3)

Pre-Seal Post-Seal

CFM50 ACH50 CFM50 ACH50 % ReductionDemo 1 After Foam 7 3 2569 23121 1690 4.39 429 1.11 75%Demo 2 After Foam 8 1 2032 22215 1286 3.47 351 0.95 73%

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Demo 1 Demo 2

Example Seals After Foam

Seals formed under trusses Seal formed at corner of wall

assembly

Option 2: Before Foam

Exposed roof deck

Rim joist penetrations

Option 2 Pre sealing work

»Large penetrations needed to be sealed prior to aerosol sealing

»Time/materials for pre-sealing was tracked

Prepare for unexpected!

Pre-Sealing Time/MaterialsSealing Penetrations Sealing Gap at Eaves

Stage/Option

Time for Manual Sealing

(person-hours) Cans of Foam Used

Time for Manual Sealing

(person-hours) Cans of Foam Used

Before Foam 1.5 3 1.5 4

Before Foam 4.5 6 1 4

*Note: Pre-sealing work performed by inexperienced staff

Option 2 Results

After Foam

CFM50 ACH50 % Reduction

483 1.25 6%

352 1.06 4%

Stage/Option Lot PlanFloor Area

(ft2)Volume

(ft3)

Pre-Seal Post-Seal

CFM50 ACH50 CFM50 ACH50 % ReductionDemo 1 Before Foam 23 3 2569 23121 5836 15.14 828 2.15 86%Demo 2 Before Foam 24 2 2223 20007 3005 9.01 477 1.43 84%

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Demo 1 Demo 2

Option 2 Example Seals

CA Builder #1 Results Summary

»39% tighter than two control houses

»55% tighter than Zero Energy Ready requirement of 2.5 ACH50 0

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Pre-Seal Post-Seal After Foam End-Const

After Foam Before Foam

Avg. 1.1 ACH50 Avg. 1.8 ACH50

Further Testing In Sealed Attics

»California Builder #2

»Homes designed with sealed attics

»Using netting and blown-in cellulose insulation at roof deck

»Fiberglass/mineral wool in wall cavity

»HRV integrated into central air handler

Conventional Sealing

Gasketed light fixtures

Can foam in expansion joint at roof deck and HVAC penetrations

Foam gasket at sill plate

CA Builder #2 – Before Insulation

Challenges

Air barrier installed to block garage attic from house attic

Gap between exterior foam and roof

CA Builder #2 Results Summary

»41% tighter than two control houses (before drywall)

»Final end of construction testing planned this week

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Before Blow-InInsulation

Before Blow-InInsulation

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Pre-Seal Post-Seal End-Const

Avg. 3.0 ACH50Avg. 5.1 ACH50

Testing In Vented Attics

»California Builder #1

»Vented attic with blow-in insulation on ceiling

»Fiberglass/mineral wool in wall cavity

»HRV integrated into central air handler

Sealing Strategy

»Sealed after drywall, mud and tape

»Temporarily covered fire sprinklers

Conventional Sealing

Sealing Results»80% reduction in leakage

»90 minutes of sealant injection

»65% below Title 24 code

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Sealing Profile for Demo 1

Example Seals

Building America Interim Results (MN)»Minnesota Builder #1

»Homes designed with ventilated attics

»Closed-cell spray foam at rim joist

» Interior poly wrap

»Fiberglass/mineral wool in wall cavity

»ERV integrated into central air handler

Conventional Sealing

Caulk at seams where wood is joined

Can foam at wire penetrations

Caulk at sill plate

Proposed Sealing Options

»Option 1: • Seal home after spray foam at rim joist

• Reinforced poly at ceiling-attic interface

• Maintain conventional sealing

»Option 2 (Ultimately not implemented): • Seal home after spray foam at rim joist

• Reinforced poly at ceiling-attic interface

• Do not install: Airtight electrical boxes

Interior poly

Sealing Results

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Reinforced poly failed

Example Seals

Seal formed between studs

Seals formed at wire penetrations

Seal formed at

electrical box

Seals formed at

plumbing penetrations

MN Builder #1 Results Summary

» 41% tighter than two control houses

» 56% tighter than Zero Energy Ready requirement of 2.0 ACH50

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#2 Demo #1 Demo Blaine Eagan Plymouth Lakeville ControlLakeville

ControlEagan

AC

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Pre-Seal Post-Seal End-Const

50% 84% 72% 82% 46% 66%

% Reduction of Sealing

Batt Insulation in Walls

IECC Code zones 3 - 8

Passive House

garage area converted to sales office

0.88 average

Final Takeaways

»Aerosol sealing was very effective• Reduced air leakage by 75-80%

• Achieved leakage rates well below codes

»Only 1-3 hours of total injection time

»Can replace many conventional sealing tasks

»Assures leakage targets are met• Provides verification

Project Path Forward

»Complete testing with vented attics

»Complete end of construction tests

»Determine cost effectiveness:• Gather cost data from builders• Compare costs and performance to conventional

sealing approaches

Research Path Forward

»Application in commercial buildings• Completed a project for DoD on non-res retrofits• Commercial buildings present challenges

Roof-to-wall connection

Supplemental manual sealing sometimes required

»Application in existing homes• Existing homes are leakier• Apply at time of tenant change