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A Research Institute of the University of Central Florida Phase 1 Investigation Potential Benefits of Revising Exception 1 under Section 101.4.7.1.1 Duct.

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Presentation on theme: "A Research Institute of the University of Central Florida Phase 1 Investigation Potential Benefits of Revising Exception 1 under Section 101.4.7.1.1 Duct."— Presentation transcript:

1 A Research Institute of the University of Central Florida Phase 1 Investigation Potential Benefits of Revising Exception 1 under Section Duct Sealing upon Equipment Replacement FLORIDA BUILDING CODE, ENERGY CONSERVATION June 26, 2014 Janet McIlvaine Sr Research Analyst FSEC Buildings Research Division

2 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Partnerships 2 Advantage Air Conditioning and Heating Systems, Inc. Florida Solar Energy Center Team: Janet McIlvaine, David Beal, Karen Sutherland, and Bryan Amos.

3 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Relevant Code Section FLORIDA BUILDING CODE, ENERGY CONSERVATION Section Duct Sealing upon Equipment Replacement (Mandatory). At the time of the total replacement of HVAC evaporators and condensing units for residential buildings, all accessible (a minimum of 30 inches clearance) joints and seams in the air distribution system shall be inspected and sealed where needed using reinforced mastic or code approved equivalent and shall include a signed certification by the contractor that is attached to the air handler unit stipulating that this work has been accomplished. Exceptions: 1. Ducts in conditioned space. 2. Joints or seams that are already sealed with fabric and mastic. 3. If system is tested and repaired as necessary 3

4 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Relevant Code Section Section says, in part: – In homes, seal accessible ducts (30” clearance) as needed at time of total HVAC equipment change out, except “ducts in conditioned space”. Does (should) this exception apply to building cavity used as return plenums in interior air handler closets? 4 Current Investigation: – Are unfinished, unsealed platform returns in conditioned space? – Are closets that function as return plenums (air handler stands) in conditioned space? – Yes and no…

5 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Relevant Code Language Definition (Chapter 2, Florida Building Code, Energy Conservation, 2011) – “Ducts in Conditioned Space. [Ducts located] interior to both the thermal envelope and the pressure envelop of the building.” By this definition, yes – this plenum (below) appears to be in conditioned space In operation, no – this plenum is directly connected to unconditioned spaces 5 Platform Return Laundry Alcove Inside Platform Return Open Wall Cavities Return Plenum has No Air Barrier 13 2

6 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Platform Return – Imaging and Testing from Previous Research Connected to Attic by Interior Wall (see references) 6

7 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Field Investigation Scoping exercise – HVAC contractor’s standard approach to return plenum “in conditioned space” – Associated burdens & projected energy use impact – NO guidance from investigators on design or install House criteria – Interior air handler closet – Platform or whole closet return plenum – HVAC equipment replacement Measure duct leakage – Cover all registers, depressurize to 25 pascals, measure flow – Results: CFM25 – Pre-retrofit – Repeated at post-retrofit Simulation analysis 7

8 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Field Investigation – Pre/Post Duct Testing 2 duct leakage tests – “Total” leakage*: All leakage (CFM25,total) – “To Out” Leakage*: Leakage only into/out of cond. space (CFM25,out) 2 duct configurations – “Entire System”* – supply, air handler, and return – “Return Only”** - system split at air handler (top, bottom, or fan) 8 Isolating the return plenum**: Cardboard in bottom of air handler cabinet to stop air flow, isolating the return plenum (underneath) during testing. * Resnet, ** ASHRAE, 2004.

9 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Field Investigation – leakage per ft 2 Calculate Normalized Duct Leakage (Qn) – Duct leakage per square foot 9 Test Result (cfm) Conditioned Area (ft 2 ) Qn = = 0.06 Qn,out = 108 cfm 1800 ft 2 1,800 ft 2 Qn,out = ,000 ft 2 Qn,out = 0.036

10 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Field Investigation – 4 Test Houses 10 House #261 Laundry Alcove Return Only Qn,out = 0.15 House #194 Living Room Closet Return Only Qn,out = 0.04 Whole Closet Plenum Drywall Air Barrier Platform Return Plenum No Air Barrier House #223 Hall Closet Return Only Qn,out = 0.10 Platform Return Plenum No Air Barrier Looking down through the gutted air handler House #1962 Converted Pantry Return Only Qn,out = 0.09 Whole Closet Plenum Drywall Air Barrier House #261 Laundry Alcove Return Only Qn,out = 0.15 Platform Return Plenum No Air Barrier Qn = leakage/ft 2 - Approximate Florida new construction Qn,out = 0.06 (Cummings, et al. 2012)

11 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement House Pre: Air Handler on Frame StandPost: Sealed Platform Return Plenum View Up Into Plenum Wall No Blocking Approx New Construction Box definig Qn Qn = leakage/ft 2 Approximate Florida new construction Qn,out = 0.06 (Cummings, et al. 2012)

12 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement House Pre: Drywalled Platform ReturnPost: Sealed Platform Return Plenum Approx New Construction Qn = leakage/ft 2 Approximate Florida new construction Qn,out = 0.06 (Cummings, et al. 2012)

13 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement 13 View Up Plenum Wall No Blocking Pre: Unsealed Platform ReturnPost: Sealed Platform Return Plenum Approx New Construction Qn = leakage/ft 2 Approximate Florida new construction Qn,out = 0.06 (Cummings, et al. 2012) House 261

14 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement House View Up Plenum Side Wall - No Blocking Pre: Unsealed Platform ReturnPost: Sealed Platform Return Plenum Approx New Construction Qn = leakage/ft 2 Approximate Florida new construction Qn,out = 0.06 (Cummings, et al. 2012)

15 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Expected Outcome and Impact on the Code: Phase 1 Report: impact of sealing building cavity return plenums in the conditioned space – Opportunity – Magnitude of opportunity – Achievable improvement – Challenges, cost, projected energy savings With Phase 2 activity, it is anticipated that the Florida Building Commission might consider limiting applicability of Exception 1 to ducted pathways, and not building cavities. Informed discussion 15

16 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Research Question 1 Was there leakage to the outside in these return plenums located in interior air handler closets? – Yes, at pre-retrofit, the return side leakage ranged from 0.09 to 0.37 for Qn,total 0.04 to 0.15 for Qn,out – If the returns were genuinely in the conditioned space, results of Test D (green box) would be zero or very close to zero: 16 “In conditioned space” should be very close to 0.00 Pre-retrofit Test Results

17 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Research Question 2 What is the magnitude of return plenum leakage compared to the entire system? – Return plenum leakage was at least 35% as high as leakage for the entire system leakage. Ranging from: 48% to 93% for Qn,total (green box) 36% to 97% for Qn,out (orange box) – This type of return plenum presents a significant opportunity to reduce overall duct leakage. 17 Pre-retrofit Qn,totalPre-retrofit Qn,out Entire System Return Only Return as % of Entire System Entire Syste m Return Only Return as % of Entire System House % % House % % House % % House % %

18 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Research Question 3 Was there improvement in the return plenum air tightness? – Yes, return plenum leakage reduction ranged from: 66% to 80% for Qn,total 71% to 100% for Qn,out - range is exemplary: 0.00* – 0.03 – Substantially lower portion of return-side leakage is to/from attic or wall cavities – Qn,out range for entire system exemplary: 0.01 – 0.07, on par with new constr. Now equal or Close to 0.00* *Below measurement threshold of test equipment. Pre-retrofit Test Results Post-retrofit Test Results 18

19 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Projected Annual Energy Cost Savings Pre/Post test results modeled with EnergyGauge USA – Annual building energy use simulation software Single base case house w/test results for each house – All characteristics except duct leakage held constant – Same SEER, size, location, duct area Compared three scenarios: – Scenario 1 - Pre-retrofit test results – Scenario 2 - Post-retrofit – Scenario 3 - Hypothetical post-retrofit What if the return had not been repaired? Currently allowable Modified post-retrofit duct leakage results to reflect pre-retrofit return plenum condition 19

20 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Projected Annual Energy Cost Savings* ($) With (#2) and Without (#3) Return Repair 20 Scenario 2 Post-retrofit Savings (Actual Return Repair) Scenario 3 Hypothetical Post-retrofit Savings (Return NOT Repaired) Estimated Annual Energy Savings Estimated Annual Energy Savings Reduced to Forfeited Savings House 1962 $93$62$31 House 194 $36$19$16 House 261 $97$29$69 House 223 $43$ 2$41 *Projected cost savings ($) accrue from reduced heating and cooling energy use

21 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Whole House Projected Annual Energy Cost Savings (%) With (#2) and Without (#3) Return Repair 21 Scenario 2 Post-retrofit Scenario 3 Hypothetical Post-retrofit - No return repair

22 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Heating and Cooling Projected Annual Energy Cost Savings (%) With (#2) and Without (#3) Return Repair 22 Scenario 2 Post-retrofit Scenario 3 Hypothetical Post-retrofit - No return repair

23 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Practicality and Simple Payback 23 Labor considerations: Contractors that do new construction already know how to do this Constrained space Existing plumbing Framing tasks Materials on hand? OTJ problem solving (training) Recaptured Savings HVAC Contractor Input Simple Payback Materials Cost Only Qn,out Return Only Material Costs Reported Labor PrePost House 1962 $31 $ years House 194 $16 $80None 4.9 years0.04--** House 261 $69 $ years House 223 $41 $752 hours 1.8 years

24 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Lifetime Savings 24 Recaptured (Projected) Annual Energy Cost Savings Life Expectancy* 7 years16 years House 1962 $31 $216 $493 House 194 $16 $115 $262 House 261 $69 $480 $1,096 House 223 $41 $288 $658 *CEE and AHRI (2014). InterNACHI (2014).

25 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Practicality 3 HVAC Contractors – 1 Approach Approach: Install an air barrier (duct board) and seal (mastic) to create a defined air flow path for return air. Effect: Isolates the return plenum from adjacent unconditioned spaces (i.e. walls, attics, floors, foundations.) 25 s good as new”. House 1962 House 194 House 261House 223 FSEC provided NO guidance on design or install. This is standard practice for these contractors.

26 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Intangible Benefits New construction code requires sealed return plenums Why? – Reduced conditioning loads – Enhanced comfort and indoor air quality – Improved building durability – Extended equipment life – Improved long term equipment efficiency (reduces filter bypass) Coupled with other measures to limit combustion safety risks Documented in other literature – Cummings, et al. (1998, 2012). – Beal, et al. (2011) 26

27 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Unanswered Questions Phase 2 proposed as six more houses – Different approaches No repair – bench mark New dry wall air barrier Poorly sealed duct board Closet + sealing – Finding contractors Partner with code officials – focus on local “norms” – Materials & labor costs Burden to contractors and homeowners Difficult to obtain Investigate existing sources of data (no cost/labor) – Previous retrofit data (40 houses) – Aggregate data from home energy raters Leverage other funded research 27

28 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Ducts in Conditioned Space New Construction 28

29 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Relevant Definitions (Ch. 2) Duct. A tube or conduit utilized for conveying air. [ ] DUCTS IN CONDITIONED SPACE. For ductwork to qualify as being in conditioned space, it shall be located interior to both the thermal envelope and the pressure envelop of the building. PLENUM. A compartment or chamber to which one or more ducts are connected, that forms a part of the air distribution system, and that is not used for occupancy or storage. A plenum often is formed in part or in total by portions of the building. 29

30 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Selected References Beal, D.; McIlvaine, J.; Fonorow, K.; Martin, E. (2011). Measure Guideline: Summary of Interior Ducts in New Construction, Including an Efficient, Affordable Method to Install Fur-Down Interior Ducts. Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: CEE and AHRI (2014). Directory of Energy Efficient HVAC Equipment. Consortium for Energy Efficiency and Air-conditioning, Heating and Refrigeration Institute. Accessed June 2014: Cummings, J.; Withers, C. (1998). “Building Cavities Used as Ducts: Air Leakage Characteristics and Impacts in Light Commercial Buildings.” ASHRAE Transactions, (104) Part 2; pp Accessed June 2014: Cummings, J.; Withers, C.; Gu, L.; McIlvaine, J.; Sonner, J.; Fairey, P.; Lombardi, M. (2002). Field Testing and Computer Modeling to Characterize the Energy Impacts of Air Handler Leakage. FSEC-CR Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: Cummings, J.: Withers, C.; Martin, E.; Moyer, N. (2012). Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single-Family Homes. Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: ENERGY STAR ENERGY STAR Qualified Homes, Version 3 (Rev. 07) Inspection Checklists for National Program Requirements. Accessed June 2014: 30

31 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Selected References, continued Fairey, P. (2009). Effectiveness of Florida’s Residential Energy Code: 1979 – (Revision of Report). Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: “Florida Building Code 2010: Energy Conservation.” (2011). Washington, D.C.: International Code Council. Accessed June 2014: “Florida Building Code 2010: Mechanical.” (2011). Washington, D.C.: International Code Council. Accessed June 2014: “Florida Building Code 2010: Residential.” (2011). Washington, D.C.: International Code Council. Accessed June 2014: InterNACHI (2014). InterNACHI's Estimated Life Expectancy Chart for Florida Homes. International Association of Certified Home Inspectors. Accessed June 2014: McIlvaine, J.; Sutherland, K.; Martin, E. (2013). Energy Retrofit Field Study and Best Practices in Hot-Humid Climate. Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: NAHB. (2007). Study of Life Expectancy OF Home Components. National Association of Home Builders. Accessed June 2014: 31

32 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Selected References, continued ASHRAE. (2004). Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal Distribution Systems. ASHRAE Standard American Society of Heating, Refrigerating, and Air Conditioning Engineers. RESNET. (2013). Mortgage Industry National Home Energy Rating Systems Standards. Oceanside, CA: Residential Energy Services Network. Accessed June 2014: Parker, D.; Dunlop, J.; Sherwin, J.; Barkaszi, Jr., S.; Anello, M.; Durand, S.; Metzger, D.; Sonne, J. (1998). Field Evaluation of Efficient Building Technology with Photovoltaic Power Production in New Florida Residential Housing. FSEC-CR Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: Swami, M.; Cummings, J.; Sen Sharma; R.; Withers, C.; Basarkar, M. (2006). Florida Building Code - Enhance Florida's Building to Next-Generation Energy & Mechanical Codes and Energy Compliance. FSEC-CR Cocoa, FL: Florida Solar Energy Center. Accessed June 2014: 32

33 Florida Building Code, Energy Conservation, Section Duct Sealing upon Equipment Replacement Section Status FLORIDA BUILDING CODE, ENERGY CONSERVATION – Section Duct Sealing upon Equipment Replacement: HB 269 states, in part: – “It is the intent of the Legislature that all replacement air-conditioning systems in residential applications be installed using energy-saving, quality installation procedures, including, but not limited to, equipment sizing analysis and duct inspection. Notwithstanding this section, existing heating and cooling equipment in residential applications need not meet the minimum equipment efficiencies, including system sizing and duct sealing.” – Filed in January, Passed and Signed by Governor in June Florida Building Commission Declaratory Statement – Question: Does HB 269 overturn the code requirements for duct sealing as stated in [ ]? Is the duct sealing certification/form still required for existing residential change outs? – Answer: “…if the duct system itself is not replaced, [House Bill] 269 overturns the code requirements for duct sealing as stated in Section [ ].” Current Investigation provides relevant field data for unsealed return plenums 33


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