Aerosol Sealing in New Construction
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This project aims to optimize aerosol sealing of building envelopes in new home construction. The timeline runs from August 2016 to July 2019, with key milestones including builder meetings in Minnesota and California in late 2016/early 2017 and sealing of initial test homes beginning in mid-2017. The budget totals $669,179 from DOE and cost-share sources. Progress includes developing a test plan, an initial builder meeting, and plans to work with selected builders to develop and test optimized sealing approaches in Minnesota and California. The goal is to provide guides enabling reliable, lower-cost envelope tightening reducing space conditioning energy use by over 10%.
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Aerosol Sealing in New Construction
- 1. Dave Bohac, dbohac@mncee.org Center for Energy and Environment Aerosol Sealing in New Construction 2017 Building Technologies Office Peer Review
- 2. 2 Project Summary Timeline: Start date: 8/1/2016 Planned end date: 7/31/2019 Key Milestones 1. Builder kickoff meetings; MN- 12/16, CA- 3/17 2. Identify sealing options; MN- 4/17, CA- 6/17 3. Seal 5 houses; MN- 8/17, CA- 10/17 Budget: Total Project $ to Date (1/31/17): • DOE: $44,244 • Cost Share: $11,089 Total Project $: • DOE: $535,037 • Cost Share: $134,143 Key Partners: Project Outcome: The project team will work with builders to optimize the integration of aerosol envelope sealing into the production building process. The sealing guides will enable builders to reduce air infiltration space conditioning energy use by over 50% which can reduce space conditioning energy use by over 10%. University of California, Davis, WCEC (Western Cooling Efficiency Center) Building Knowledge, Inc. University of Minnesota, Cold Climate Housing Program Aeroseal, LLC.
- 3. 3 Purpose and Objectives Problem Statement: High performance moisture managed envelopes require more effective air barriers that require add cost, training, and quality control. Target Market and Audience: Aerosol envelope sealing can improve the energy performance of all residential new construction. This project will focus on single family new construction, but many of the lessons learned could be applied to other residential units. Approximately 1 million new residential units were built in 2014. In 2009 40% of residential energy use was attributed to space heating and cooling which is impacted by air infiltration loads from leaky envelopes. Impact of Project: This project will provide guides and builder case studies for optimal integration of aerosol envelope sealing for new home construction. The project team will work with builders in Minnesota and California to identify options for when to seal and what current sealing could be eliminated. The tightness and net cost of the aerosol sealed houses will be compared to results for their standard construction. The goal is to produce reliably tighter houses for equal or lower cost.
- 4. 4 Aerosol Envelope Sealing Technology: • Pressurize enclosure for 1 to 2 hours while applying aerosol “fog” • Sealant particles find and seal leaks as air escapes house • Capable of simultaneously measuring, locating, and sealing leaks in a building envelope. Benefits: • Envelope tightness improved by 60% to 95% • Reduced training and quality control for eliminated conventional sealing • Reliable tightness to meet requirements, know when to “stop”, and certification test
- 5. 5 Leakage Results: 18 New Construction MF Units Average leakage: pre= 3.9 ACH50, post= 0.7 ACH50 54% to 95% below code requirement, average= 77%
- 6. 6 Approach Key Issues: • Previous Building America projects showed 60% to 95% improvements in envelope tightness. • Sealing typically applied after drywall in place. No experience with ability to replace current sealing methods. Approach: • Iterative approach with multiple builders – when & what to eliminate • Assess current sealing methods for a MN & CA builder and develop two approaches for each • Net cost and tightness will be evaluated against standard methods • Process repeated with second set of houses for first builders and a set of houses for additional builders.
- 7. 7 Progress and Accomplishments Accomplishments: • Planning complete: Test Plan and Project Management Plan • Held kickoff meeting for Minnesota builders and starting outreach for California meeting • Developing assessment protocol • Field work delayed – did not want to apply sealing under most challenging conditions (e.g. Minnesota winter) Market Impact: • Working with manufacturer (Aeroseal) – direct application of results • Aeroseal’s duct sealing contractors seal about 15,000 systems/year & planning to develop envelope contractors by end of 2017 – DOE Energy 100 award – ASHRAE 2016 Product of the Year Award • Large and/or visible builders to improve credibility
- 8. 8 Progress and Accomplishments Lessons Learned (Builder Kickoff Meeting): • Interested in sealing after mechanical penetrations/before insulation • Eliminate 4 ml poly interior? • Change rim joist spray foam approach? • Seal ducts from outside > in? • Likely to need help working with code officials to approve some changes • Significant interest, but time for corporate approval & other priorities MF New Construction • 71% to 94% reduction • Post ACH50: 0.16 – 0.66 • Post cfm50: 25 - 114
- 9. 9 Project Integration and Key Partners: • UC Davis Western Cooling Efficiency Center developed technology and working on other efforts to promote aerosol sealing in other markets • Aeroseal corporation will be conduit to contractors who perform work • Building Knowledge is established air sealing and energy efficiency consultant for homebuilding industry • University Minnesota Cold Climate Housing experienced builder trainer/educator Communications: • Presentations at ACEEE Summer Study, Better Buildings Better Business, & Home Performance Conference: primarily previous MF results but discussing current BA project Project Integration and Collaboration
- 10. 10 • Agreement with first MN builder • Assess houses and develop sealing options 1st MN builder (March/April) • Seal 1st five MN houses (May – August) • CA effort ~ 2 months after MN • California builder kickoff meeting (March/April) • Seal 1st five CA houses (June – Sept) • Repeat for second set of houses for first builders • Repeat for houses for another builder in MN and CA Next Steps and Future Plans Waiting for the winter thaw
- 12. 12 Project Budget: The total project budget is $669,179 (DOE: $535,037; Cost Share: $134,143). About 7% of the funds will be used by Aeroseal staff to seal houses, 11% by Building Knowledge for builder engagement, and remainder split between CEE and WCEC to implement project. Current expenses were used primarily to generate the Test Plan and conduct first builder kickoff meeting. Variances: Expenses in FY 2017 have been less than expected due to the decision to move back initial field work to warmer weather and delays in partner invoices. Cost to Date: DOE: $44,244, Cost Share: $11,089; 8.3% of the project budget has been spent to date. Additional Funding: Builder’s staff time for project was uncertain and has not been included as cost share. Budget History 8/1/2016 – FY 2016 (past) FY 2017 (current) FY 2018 – 9/30/2018 (planned) DOE Cost-share DOE Cost-share DOE Cost-share $11,218 $2,813 $224,169 $58,761 $200,103 $47,872 Project Budget
- 13. 13 Project Plan and Schedule • Three year project that started August 2016 & planned to be completed July 2019. • Final Test Plan and MN builder kickoff meeting complete. • Split builder kickoff meetings for MN & CA, so CA meeting is being held later (closer to start of field work). Delayed initial sealing work to warmer weather- project put on 2 month hiatus. • Work with first MN builder expected to start in March with sealing to start in April-May. CA work will start about 2 months after work in MN. • First go/no-go decision point is to have first two builders recruited by July 2017. Project Schedule Project Start: August 2016 Projected End: July 2019 Task Q1(Oct-Dec) Q2(Jan-Mar) Q3(Apr-Jun) Q4(Jul-Sep) Q1(Oct-Dec) Q2(Jan-Mar) Q3(Apr-Jun) Q4(Jul-Sep) Q1(Oct-Dec) Q2(Jan-Mar) Q3(Apr-Jun) Q4(Jul-Sep) Past Work Q1 Milestone: Final version of Test Plan Q1 Milestone: MN builder kickoff meeting Q1 Milestone: CA builder Kickoff meeting Current/Future Work Q2 Milestone: MN builder 1 sealing options Q3 Milestone: MN builder 1 seal five houses Q? Milestone: CA builder 1 sealing options Q? Milestone: CA builder 1 seal five houses Completed Work Active Task (in progress work) Milestone/Deliverable (Originally Planned) Milestone/Deliverable (Actual) FY2016 FY2017 FY2018
Editor's Notes
- This is a new project that started in August of last year. We are very excited about this aerosol envelope sealing technology. We have worked with this sealing method on a project to seal new and existing MF units in MN where it was incredibly successful. We obtained typical leakage reductions of over 80% in the new construction units and 75% in the existing units. This project will allow us to apply the technology to the single family new construction market.
- The issue addressed by this project is reducing the envelope air leakage of single family new construction houses. This is primarily a concern for space conditioning energy use. In 2009 about 40% of residential energy use was associated with space conditioning and typically 25% of that is due to air infiltration loads. Given that there were about 1 million residential units built in the US in 2014, this technology has the potential to produce significant reductions in residential energy use. In addition, air leakage through high performance walls can cause moisture issues. So this technology can also improve the durability of our houses. The limited field tests that have been performed show that aerosol envelope sealing can produce much tighter envelopes than possible by conventional sealing methods. However, further work is necessary to determine the best application of this method. We will be working with two builders in MN and two in CA to determine the tradeoffs for when during the construction process the sealing is applied. In addition, we will be looking for current sealing methods that could be eliminated when the aerosol sealing is applied to offset some or all of the cost of the aerosol sealing. So there could be little or NO net cost for the aerosol sealing. We see the aerosol envelope sealing as a new tool for the builders that will be applied in different ways. For MN where our code requires a tightness of 3 ACH50 this may be a method for handling specific air barrier details that they are having difficulty addressing with other methods or they may use it to eliminate other sealing approaches for a net cost reduction. For states like Texas, Penn, Alabama, Kentucky that are building to 7 ACH50, they may want to use it to go below the code requirement or if there are builders who are struggling to meet code, this will provide a method to reliably meet code.
- Just a quick overview of the technology. For those of you who are familiar with the aerosol duct sealing method, it is the same approach but now the entire house is being and not just the duct system. The house is pressurized to about 100Pa and multiple sprayers are used to release a fog of sealant. The sealant is an off the shelf, low VOC synthetic acrylic product used for exterior air barriers. In this application it is diluted and sprayed into the inside of the house. As air moves through leaks it brings the sealant with it and some of the particles attach to the edge of the leak. Over time the process fills the gaps. Sealing is typically completed in an hour or two – depends on the size of the leaks. Narrower gaps of 3/8” will be filled in the first hour and wider gaps require more time. We’ve seen leakage reductions from 60 to 95% in multifamily and single family houses. A key advantage is that the methods find and seal leaks – you don’t need to search them out. In addition, you get continuous readout on the house leakage. So if you have a specific target that you reach you can monitor the status and decide how long you want or need to seal. At the end the sprayers are shut down and a leakage test performed for certification purposes. Sealant is a synthetic acrylic – typically rolled or sprayed on for monolithic exterior air barrier. Diluted for aerosol application. Sealant is low VOC: GREEN Guard Gold Certified for use in California school and health care facilities.
- This bar chart shows results from our MF project. Key points are that ALL units sealed by at least 65% and on average they had a tightness of 0.7 ACH50 after sealing. Overall, the sealing worked very well. These bars show the pre and post total unit air leakage for the units in the new construction buildings. The solid bars are the pre value and the hashed bars the post. The percent reduction ranged from 67% to 94% with an average of 81% and average post ACH50 of 0.69. The units were 54% to 95% tighter than new code requirement of 3.0 ACH50 (using the total leakage). The tightest unit was 25 cfm50. {Building B was required to meet the EPA ENERGY STAR Multifamily High Rise tightness criterion of 0.3 cfm50/sf} {Building A- presealing exterior and floor below leakage was average 45% of total} {Building B- exterior pre-sealing leakage averaged 0.64 ACH50}
- While previous projects have shown that aerosol envelope sealing can significantly reduce leakage, there is work left to be done to determine best methods for its application for SF new construction. For example, the sealing has always been applied after insulation and drywall is complete and there hasn’t been any work to see what manual sealing could be eliminated and still produce tight houses. We are going to be working with two builders in MN and two in CA. We will be assessing their current air sealing strategies and provide them a demo of the aerosol sealing method. Then we’ll sit down with them to discuss options for when to seal in the construction process and what current sealing they’d be comfortable removing from their process. We will track costs and compare aerosol sealed houses to ones that go through their normal construction process. This will be done in an iterative fashion so that what we learn in the early portion of the project will be applied to later houses.
- As I’ve noted this is a new project, so we are still getting started. We have had a kickoff meeting with MN builders and will have a meeting with CA builders this next month. We had thought that we would start the process in MN in Jan/Feb, but decided that dealing with the heating requirements to seal in MN in the middle of winter would be challenging and that we would delay the field work to late winter/early spring. We see potential for large scale impact of this technology. We are working with Aeroseal who will be doing the air sealing. Through their dealer network they seal about 15,000 duct systems/year. They have a proven capability to deliver large scale implementation. They recently announced at RESNET that in early 2018 they will be establishing a network of AeroBarrier dealers who will be able to perform this new envelope sealing work. {Minnesota builders: DR Horton, M/I Homes, Amaris Custom Homes, Country Joe, {CA builders: VP of Research and Building Technology with Lennar Homes, KB Homes, Meritage Homes, De Young properties}
- All of the builders were interested in applying the sealing BEFORE insulation and drywall. Sheathing and windows installed – need top on house to complete air barrier- either poly or drywall on ceiling. MN builders often do this in winter so that they can heat the house during construction. Aerosol creates air barrier and use low Perm paint – might not need interior poly sheet. May also allow different approach insulating rim joists than spray foam Might be possible to use this process to seal ductwork. Seal when ductwork is still exposed. Seal registers and use ERV duct to open ducts to outside so that there is pressure across the ducts. The seal would be created on the OUTSIDE of the ducts. Expect that building officials may have concerns with some of these approaches and our project team will work proactively with them All builders expressed interest. None have committed yet. We had a meeting with another production builder yesterday and we should know by the end of the week whether they will participate.
- Our project team includes UC Davis Western Cooling and Efficiency Center which has developed this technology. They will be working with the CA builders. Aeroseal corporation will be doing the air sealing work. Building Knowledge has worked with builders to improve their air barrier approaches- they are heading our builder outreach efforts. Pat Huelman with the Univ MN is consulting on application issues. We have given presentations at a number of conferences regarding the results from previous projects and have discussed the goals for this project.
- Our primary focus is to recruit the first MN builder. We would like to start the assessment process in the next month, establish sealing approaches, and start sealing houses in May. There will be similar efforts in CA that lag our work in MN by a couple of months. The second builders in MN and CA would start about 4 – 6 months after the first. This process has been established to allow us to learn from the first builders and apply those experiences to the following ones. Working with multiple builders and two states will also give us different perspectives on how to apply this technology.