2012 09 - eeba nahbrcip-prod_bldr struct design
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    2012 09 - eeba nahbrcip-prod_bldr struct design 2012 09 - eeba nahbrcip-prod_bldr struct design Presentation Transcript

    • A Production Builder’s Guide toEnergy Efficient Structural DesignEnergy Efficient Framing SystemsEEBA Excellence in Building ConferenceTuesday, September 25, 2012Salon CAmber Wood, NAHBRC
    • NAHB Research Center IndustryPartnershipMission:Promote innovation toimprove the quality,durability, affordability,and environmentalperformance housing.2
    • Outline High Performance Frame Wall System Framing Details Air Sealing Details Whole House Examples3
    • 4.InfrastructureDevelopment4.InfrastructureDevelopment3.EffectiveGuidanceand Tools3.EffectiveGuidance andTools2.House-as-a-SystemBusiness Case2.House-as-a-SystemBusiness Case1.AdvancedTechnologies &Practices1.AdvancedTechnologies &PracticesBuilding America Innovations This research is paving the way for keyinnovations: Energy Efficient Components New Home Whole-House Packages High Performance Home Solutions4
    • Builder Resources Climate-specific considerations Code-related considerations Detailed drawings “Wrong ” and “right” way-to-do-it examples Training materials Technical references Link to DOE resources:www.buildingamerica.gov5
    • What is the Question? Can we advance framing further??6
    • Why Do We Care? Goal . . . Build “highperforming homes” that are Energy efficient Durable Comfortable Healthy to live in Safe Affordable AchievableIn other words . . . Green. 7
    • Specific Technical Approach Insulated 3-stud corners Rim headers Continuous drywall approach Modular Fireplaces8
    • The Solutions . . .9
    • Advanced Wall Framing Design Cost effectively go from 2x4 to 2x6 walldesign10
    • Framing: Advanced Design Typical Wall Stud Count: 52 Framing: 20% Energy Efficient Wall Stud Count: 37 Framing: 13%11
    • Insulated 3-Stud Corner12
    • Interior Wall Intersection13
    • Integrated Rim Header & Load Path14
    • 15
    • Integrated Rim Header16
    • Integrated Rim Header17
    • Modular Fireplace Construction18
    • Fireplace ConstructionTypicalModular19
    • Framing & Air Sealing:Offset Interior Wall Intersection20
    • Continuous DrywallCourtesy of K-Hovnanian21
    • Continuous Drywall22
    • Whole-House Solutions23
    • 30% New Construction Test House Single-story slab-on-gradesingle family design Mixed-Humid CZ 4 Production builder Same model with same floorplan and orientation two lotsaway24
    • Design Considerations SolutionImproved Air SealingDetailed air sealing improvement measures balanced with cost andconsistency of installationIncreased InsulationOptimized framing plus exterior structural insulation to increasethermal performanceImproved HVAC system efficiency, airdelivery, & occupant comfort forsingle-story slab-on-grade designsRedesigned HVAC system:Equipment located in conditioned spaceReturn duct simplified & located in conditioned spaceSupply duct deeply buried, well sealed, trunk located within trusschaseQuality Assurance & ControlChoose construction details with consideration for builder & tradeapproachesConstruction specifications, preparatory meetings, and sitemonitoringRepeatable DesignEnhanced features to optimize performance and cost as well asensure consistent installationCost Effective Energy Solutions25
    • Thermal EnvelopeFeature Standard Practice NCTH Enclosure EnhancementsFoundationSlab on grade2’ perimeter insulation, R-10Standard plus:R-10 edge insulationWalls2x4 frame, 16” o.c.R-13 batt insulation, Class 1Standard plus:Panelized walls1” Structural Insulated Sheathing (SIS), R-6.5Continuous drywall method3-stud cornersWindows U = 0.37 U = 0.34, SHGC = 0.26Air SealingWall bottom plates caulkedPenetrations sealedWindow rough openingsfoamedStandard plus:SIS panels– Gasketed at top & bottom plates– Taped seams– Provides WRB & air barrierFoam over top plates from atticFoam over HVAC trunk & register bootsFramed cavities & knee wall air barriersGarage-side drywall & electrical boxesRoof/attic (vented)Truss, top chord overhangR-38, loose fill fiberglassRaised heel truss, cantilevered overhangR-49, loose fill fiberglass26
    • Factory installed sheathinggasketsFactory installed sheathing tape27
    • Sealed air barrieradjacent to garageknee wallSealed air barriers at fireplace framed cavity andcoffered ceiling beyondSealed Air Barriers28
    • Partition wall held 1” at exterior forcontinuous drywall methodTop plates foamed from atticAir Sealing Methods29
    • Sealed top plates and airbarrierSealed top plates of partitionwall and exterior wallSealed Top Plates30
    • 31
    • Estimated Annual Source Energy(Mbtu/yr)Estimated Annual Utility Bills($/yr)End Use BAB NCTH Savings BAB NCTH SavingsFixed Charges 192 192 0Space Heating 121.3 74.2 39% 1,458 891 567Space Cooling 7.5 3.7 50% 94 47 47HVAC fan 5.7 3.4 40% 72 43 29Hot Water 21.7 11.0 50% 261 132 130Lighting 24.2 19.0 21% 306 240 65Appliances & MELs 61.6 55.0 11% 776 694 83OA Ventilation 3.2 1.9 40% 40 24 16Total 245.2 168.2 31% $3,200 $2,263 $937Total (size adjusted) 243.3 168.2 31%Site Generation (49.4) ($880)Net 243.3 118.8 51% $3,200 $1,383 $1,817Simulated Energy Savings – BEopt v1.132
    • Incremental Cost Analysis33Group CategoryBuilders NetAdditional Cost(labor &materials)Adjusted(no framingcredit)Framing1" SIS sheathing $ 1,591Panelized walls credit $ (3,320)Truss (raised heel & HVAC chase, simplifiedwithout coffers, adjusted for site built coffers &air barriers) $ 0Roof/attic R-49 insulation $ 525Air sealing Spray foam top plates & duct $ 1,300WindowsImproved efficiency rating $ 150Jamb extensions $ 350HVAC Entire System $ 238Plumbing Tankless direct vent water heater $ 350Lighting 100% CFL $ 280Total Additional cost of options $ 1,464 $ 4,784Net total Adjusted for 10% builder margin $ 1,627 $ 5,316Net Monthly CostMortgage net monthly cost $ 11 $ 35Utilities net monthly cost $ (78) $ (78)Net monthly cost $ (67) $ (43)
    • Performance TestingPerformance Metric Standard Model NCTH Change UnitsHouse Size 2,587 2,498- 3%sq.ft.House Volume 23,542 22,732 cu.ft.Infiltration2,717 1,021- 61%CFM506.9 2.7 ACH500.37 0.15 ACHnatNormalized Infiltration 1.05 0.41 CFM50/sq.ft.Total Duct Leakage 165 85 - 48% CFM25Duct Leakage to Outside 74 0 - 100% CFM2534
    • Performance MonitoringPerformance MetricDec ‘09 – Jan ’10Standard Model 30% Test House ChangeGas Heating Energy (therms) 286 137 - 52%Furnace Electricity (kWh) 335 145 - 57%35
    • 30% New Construction Test House Three-story Queen Annestyle single family design Finished basement & loft Mixed-Humid ClimateZone 4 Production builder36
    • Design Considerations SolutionImproved Air SealingDetailed air sealing improvement measures balanced withimplementation cost and consistency of installationIncreased InsulationOptimized 2x6 framing with densely blown fiberglass insulationincreased thermal performance and reduced framing factorImproved HVAC system efficiency, airdelivery, & occupant comfortReduced the number of HVAC systems from the traditional twosystems to oneRedesigned floor plan, framing, and ducts to locate entire HVAC anddistribution system in conditioned space for significant savingsImproved equipment operation efficienciesImproved ventilation, filtration, and occupant comfortQuality Assurance & ControlPlanning stage design reviews included practical input from WHI,vendors, and trade partnersDeveloped construction details and specifications for plan setEstablished construction monitoring points (review, inspection, test)Repeatable DesignSpecified features which optimized performance, cost, & practicalimplementation37Cost Effective Energy Solutions
    • Thermal EnvelopeFeature Standard Practice NCTH Enclosure Enhancements – Standard PlusFoundationInground basementR-10Inground basementR-13Walls2x4 frame, 16” o.c.R-13 batt insulation, grade 1Panelized walls2x6 frame, 24” o.c., optimized framingStructural rim joist headersR-24 blown fiberglassWRB installed as air barrierWindows U = 0.35, SHGC = 0.35 U = 0.31, SHGC = 0.28Air SealingWall bottom plates caulkedPenetrations sealedWindow rough openings foamedSprayed sealant as primary air seal at all OSB seamsand framing intersectionsSprayed sealant as gaskets at framing behindcontinuous drywallRedundant air barriers – sealant, continuous drywalland house wrap, tapedRoof/attic(partially vented)Truss, top chord overhangR-38, loose fill fiberglassRaised heel truss with 2’ overhangR-49 blown fiberglass with full depth at eaves andsloped ceilings38
    • Interior wall held back sothat exterior wall receivescontinuous drywallLimit of 2-plyrim joistheaderRim Joist Header & Continuous Drywall39
    • Rim headers and HVAC supply trunk cutout 402x6 panelized walls at 24” o.c,Floor joists at 24” o.c. withfactory installed mechanicalchase cutouts
    • 2nd floor1st floor3rd floorDuct layout in 3-D plan to assureaccurate and consistent installation41
    • House wrap as air seal,taped at top and bottom42Air Sealing
    • Continuous Drywall Approach Seal drywall at: Top plate Bottom plate Around receptacles Can use: Foam Gasket Caulking43
    • 44Tested insulation densityWalk-thrurevealedmissinginsulation Thermaland airbarrierElastomeric air seal at:• Top/ bottom plates• Wall junctionsAirtight Drywall Approach
    • Quality Assurance Plan –Inspect, Test, RetestPerformance Metric NCTH UnitsHouse Size4,441 SF finished area4,568 SF conditioned areaHouse Volume 41,847 CFInfiltrationTest 1A Test 2B Final2,400 1,380 1,335 CFM503.4 2.0 1.9 ACH500.17 0.10 0.10 ACHnat0.53 0.30 0.29 CFM50/SFcfaA Prior to trim and sealing of all penetrations but after sheetrock installationB After access panels and other knee walls from the 3rd floor room to the attic were sealedC Final after all finishes complete45
    • Simulated Energy Savings – BEopt v1.1Estimated Annual Source Energy(Mbtu/yr)Estimated Annual Utility Bills($/yr)End Use BAB NCTH Savings BAB NCTH SavingsSpace Heating 96.8 58.9 39.2% 1,425 867 39.2%Space Cooling 26.5 17.0 35.8% 344 221 35.8%Hot Water 23.7 14.5 38.8% 348 214 38.5%Lighting 41.1 25.6 37.7% 533 333 37.5%Appliances & MELs 75.9 71.0 6.5% 1001 936 6.5%OA Ventilation 4.9 2.9 40.8% 63 38 39.7%Total 268.7 190.0 29.6% $3,715 $2,608 29.8%Total (size adjustment) 26.3 190.0Site Generation (0.0) Savings (0.0) SavingsNet 242.4 190.0 21.6% $3,715 $2,608 29.8%46
    • Activity CategoryBuildersEstimatedIncremental CostWalls2” x 6” wall studsR-24 blown in mesh fiberglass insulation$ 3,088Rim joist headers in lieu of wall headers Not estimatedRaised heel trusses Not estimatedAttic R-49 blown cellulose in attic $ 100Air sealing Spray latex air seal $ 1,910WindowsImproved efficiency rating $ 0Jamb extensions Not estimatedHVACSingle HVAC system w/higher efficienciesMulti-zone duct system in conditioned space$ 2,155Supply side ventilation $ 600Water Heating 74% efficient 50 gallon tank gas water heater $ 350Lighting 80% CFL $ 126Miscellaneous Appliances, etc. $ 1,434Total Estimated cost of upgrades $ 9,763Net MonthlyCostMortgage net monthly cost (7%, 30 years) $ 65Utilities net monthly savings $ (92)Net monthly cost/(savings) $ (27)Incremental Cost Analysis47
    • Performance Testing48courtesy of www.winchesterhomes.comLocationTemperature (°F)Jun 21, 8 am Jun 21, 4 pm Aug 17, 1 pm1st floor at thermostat 70.6 71.6 72.22nd floor master bedroom 70.4 71.6 72.13rd floor bedroom 70.7 72.6 73.5Basement recreation room 69.7 70.9 72.3
    • What was learned? Success! More work . . . Builder’s Guide Moisture performance49
    • Related Research . . .50
    • Wind Resistance of Walls withExterior FoamStud failure atpredrilled hole51
    • Moisture Research: Test Huts
    • Moisture Research: Field MonitoringMoistureSensorsMoistureContentScrewsInternalSensorAntenna53
    • Looking Ahead . . .54
    • Future Efforts Develop prescriptive methodology for use withadvanced framing details Prescriptive tables for integrated rim headerapplication Concise list of advanced framing features Training materials to educate code officials onaspects of advanced framing Develop Builder’s Guide for High PerformingWalls55
    • 56
    • Amber WoodNAHB Research CenterManager, Energy Programs400 Prince George’s BlvdUpper Marlboro, MD 20774301.430.6309awood@nahbrc.comwww.nahbrc.com • www.toolbase.orgThank You!