Marine Climate Case StudyMiranda HomesNAHB Research Center

Residential Building Energy Efficiency Meeting July 2010

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Details Unique aspects

Construction Energy Analysis Energy

Monitoring Comparison

Summary

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Project Location

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Miranda Homes • Harbor View Clackamas, OR

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Miranda Homes • Harbor View Clackamas, OR

Harbor View Model Harbor Home 1

Marine Climate 1,569 sqft Crawlspace

foundation Panelized Walls Steel framed homes Affordable, ↓cycle

time

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System Description Specifications

Foundation Unvented Crawlspace R-23 (ICF)

WallsPanelized Walls

Continuous SheathingSpray Foam Insulation

Exterior Rigid Foam Insulation

Advanced steel framing (2 x 6)OSBR-24R-4.4

Roof / Attic Spray Foam R-45 unvented attic

Windows High Performance Windows Low-e; U = 0.30 / SHGC = 0.31

Heating System Electric Heat PumpLocated in Conditioned Space 8.5 HSPF

Cooling System Central Unit Located in Conditioned Space 15 SEER

Ducts Located in Conditioned Space 100% interior5% leakage to exterior (28.4 cfm25)

Ventilation Fresh Air Ventilation 38 cfm exhaust ventilation

Water Heater Electric Hot Water Heater 0.92 EF electric tank

Lighting 75% fluorescent CFL and permanent

Appliances Energy Star (where supplied)

Air Infiltration Air Sealing Details 2.31 ACH50

Details Miranda Homes • Harbor Home 1

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Construction ProcessMiranda Homes • Harbor Home 1

Manufacture steel studs

Panelize Walls Steel studs OSB Exterior rigid foam

Set walls on foundation ICF Conditioned crawl

Manufacture roof trusses

All SPF insulation AG

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Panelized 2x6 WallsMiranda Homes • Harbor Home 1

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Wall InteriorMiranda Homes • Harbor Home 1

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Spray Foam AppliedMiranda Homes • Harbor Home 1

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Ducts & HVACMiranda Homes • Harbor Home 1

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Lighting & AppliancesMiranda Homes • Harbor Home 1

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Energy AnalysisMiranda Homes • Harbor Home 1

House Feature Typical Construction Miranda Homes Design Floor Area 1569 square feet, single story 1569 square feet, single storyWindow area 252 square feet 252 square feetFoundation Crawlspace, R-30 floor Crawlspace, conditioned, R-23Bathrooms 2 2Ceiling Flat ceiling, vented attic R38 Unvented attic, R-45Roof framing Wood MetalWall framing Wood, 2x6, advanced framing Metal, 2x6, 20% framing factor1

Wall insulation R-19 cavity R-24 cavity, R-4.35 exteriorWindows U-0.35/0.4 SHGC U-0.30/0.31 SHGCInfiltration 0.35 ACHnat2 0.122 ACHnatVentilation None 100 CFM, runtime 20% minimumCooling System Efficiency 13 SEER 15.5 SEERHeating System Efficiency 7.7 HSPF 8.5 HSPFDuct Location Interior/Crawlspace, insulated InteriorDuct sealing Assumed air-tight As measuredTemperature Set-point 76 Cooling – 71 Heating 76 Cooling – 71 HeatingLighting Energy 2,064 kWh/yr 1,183 kWh/yearAppliances and Plug 4,399 kWh/yr 4,399 kWh/yr1 Framing system optimized using panelization software and engineered components2 Based on ASHRAE 62.2 minimum infiltration before mechanical ventilation required

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Energy AnalysisMiranda Homes • Harbor Home 1

46% Energy Savings Over BA

Benchmark HERS Index

69 (w/out PV)

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MonitoringMiranda Homes • Harbor Home 1

Instruments were installed to monitor: Indoor and outdoor

temperatures Whole-house electricity

use Heating system electricity

use Water heating electricity

use Duct supply and

ventilation temperatures

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Weather Data ComparisonHeating Degree Days

Temperature difference between indoors & out

During monitoring period

15% fewer heating degree days 2,941 HDD monitored 3,468 HDD

simulations

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Weather Data ComparisonDaily Temperature Profile

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Temperature DataDaily Average Temperature Profile

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Temperature Data Profile

Measured Temp Daily Average: ≈ 2°F higher

than TMY3 Average Min: ≈ 1°F higher Average Max: ≈ 3°F higher Average Interior: within 1°F Daily Interior temperature

range is larger (over 2°F during heating season)

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Monitored DataMiranda Homes • Harbor Home 1

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Performance ComparisonSimulated vs. Measured for Period

Performance Metric Simulation Data

Measured Data Unit

Difference between Measured and Simulated Data

Average Outdoor Temperature 48.3 49.0 °F +0.7 °F Average Daily Maximum Temperature 56.6 60.1 °F +3.5 °FAverage Daily Minimum Temperature 39.9 41.0 °F +1.1 °FAverage Indoor Temperature 71.7 70.8 °F -0.9 °FHeating Energy Use 2,646 2,319 kWh -12.4%Hot Water Energy Use 1,819 1,427 kWh -21.6%Appliance and Lighting Energy Use 3,179 2,692 kWh -15.3%Whole House Energy Use 7,644 6,438 kWh -15.8%

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Heating ComparisonElectric Energy & Temperature

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Heating ComparisonHeating System Performance

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Company StructureMiranda Homes • Harbor Home 1

Miranda Homes staff construct homes Vertically integrated Minimize construction

time Minimize callbacks

Integrated Quality Management

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Conclusions & Next Steps Miranda Homes • Harbor Home 1

Energy efficiency enhancements have enabled successful use of steel framing

Monitored data is fairly well matched with predicted data & confirms savings

Simulation model adequately predicts energy usage

Further analysis is needed using annual data

Based on data further enhancements may be identified

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Questions?

Amber WoodProgram Manager, Energy Efficiency

NAHB Research Center301-430-6309

awood@nahbrc.com