5. 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
p. 5
6. Details
Miranda Homes • Harbor Home 1
System Description Specifications
Foundation Unvented Crawlspace R-23 (ICF)
Panelized Walls Advanced steel framing (2 x 6)
Continuous Sheathing OSB
Walls
Spray Foam Insulation R-24
Exterior Rigid Foam Insulation R-4.4
Roof / Attic Spray Foam R-45 unvented attic
Windows High Performance Windows Low-e; U = 0.30 / SHGC = 0.31
Electric Heat Pump
Heating System
Located in Conditioned Space 8.5 HSPF
Central Unit
Cooling System 15 SEER
Located in Conditioned Space
100% interior
Ducts Located in Conditioned Space
5% 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
p. 6
7. Construction Process
Miranda 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
p. 7
13. Energy Analysis
Miranda Homes • Harbor Home 1
House Feature Typical Construction Miranda Homes Design
Floor Area 1569 square feet, single story 1569 square feet, single story
Window area 252 square feet 252 square feet
Foundation Crawlspace, R-30 floor Crawlspace, conditioned, R-23
Bathrooms 2 2
Ceiling Flat ceiling, vented attic R38 Unvented attic, R-45
Roof framing Wood Metal
Wall framing Wood, 2x6, advanced framing Metal, 2x6, 20% framing factor1
Wall insulation R-19 cavity R-24 cavity, R-4.35 exterior
Windows U-0.35/0.4 SHGC U-0.30/0.31 SHGC
Infiltration 0.35 ACHnat2 0.122 ACHnat
Ventilation None 100 CFM, runtime 20% minimum
Cooling System Efficiency 13 SEER 15.5 SEER
Heating System Efficiency 7.7 HSPF 8.5 HSPF
Duct Location Interior/Crawlspace, insulated Interior
Duct sealing Assumed air-tight As measured
Temperature Set-point 76 Cooling – 71 Heating 76 Cooling – 71 Heating
Lighting Energy 2,064 kWh/yr 1,183 kWh/year
Appliances and Plug 4,399 kWh/yr 4,399 kWh/yr
1 Framing system optimized using panelization software and engineered components
2 Based on ASHRAE 62.2 minimum infiltration before mechanical ventilation required
p. 13
14. Energy Analysis
Miranda Homes • Harbor Home 1
46% Energy
Savings
Over BA
Benchmark
HERS Index
69 (w/out PV)
p. 14
15. Monitoring
Miranda 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
p. 15
16. Weather Data Comparison
Heating Degree Days
Temperature difference
between indoors & out
During monitoring
period
15% fewer heating
degree days
2,941 HDD monitored
3,468 HDD simulations
p. 16
19. 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)
p. 19
21. Performance Comparison
Simulated vs. Measured for Period
Difference between
Simulation Measured
Performance Metric Unit Measured and
Data Data
Simulated Data
Average Outdoor Temperature 48.3 49.0 °F +0.7 °F
Average Daily Maximum
56.6 60.1 °F +3.5 °F
Temperature
Average Daily Minimum
39.9 41.0 °F +1.1 °F
Temperature
Average Indoor Temperature 71.7 70.8 °F -0.9 °F
Heating Energy Use 2,646 2,319 kWh -12.4%
Hot Water Energy Use 1,819 1,427 kWh -21.6%
Appliance and Lighting Energy
3,179 2,692 kWh -15.3%
Use
Whole House Energy Use 7,644 6,438 kWh -15.8%
p. 21
24. Company Structure
Miranda Homes • Harbor Home 1
Miranda Homes staff
construct homes
Vertically integrated
Minimize construction time
Minimize callbacks
Integrated Quality
Management
p. 24
25. Conclusions & Next Steps
Miranda Homes • Harbor Home 1
Energy efficiency Simulation model
enhancements have adequately predicts
enabled successful energy usage
use of steel framing Further analysis is
Monitored data is needed using annual
fairly well matched data
with predicted data Based on data further
& confirms savings enhancements may
be identified
p. 25
26. Questions?
Amber Wood
Program Manager, Energy Efficiency
NAHB Research Center
301-430-6309
awood@nahbrc.com
p. 26
Editor's Notes
Typical code – Oregon code
Harbor House 1 experienced milder weather conditionsWhile the temperatures vary, they appear sufficiently close for a meaningful comparison.
The heating system analysis attempts to use statistical methods remove ambient temperature data as a variable
Vertical integration from load and bracing design and layout to stud and truss fabrication through mechanicals and finish