2011 03-14 nahbrc-greenprints afford-housingefficiency
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Affordable Housing Focus on Efficiency
Remodeling & Passive House Approaches
Greenprints Conference March 14, 2011Amber Wood, Manager Energy Programs
NAHB Research Center
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The NAHB Research Center’s mission . . .
promote innovation in housing technology to improve the quality, durability, affordability, and environmental performance of homes and home building products.
Department of Energy Programs
Building America DOE’s residential research &
development (R&D) program
Builders Challenge DOE’s energy efficiency
certification for homes
Building America
Private/public R&D partnership sponsored by DOE
Energy-efficient solutions for new and existing housing Technologies/Systems Whole-House Test Homes Quality Processes
High Performing Home Goals
“High Performing Homes” that are Energy efficient Durable Comfortable Healthy to live in Safe
Affordable
In other words . . . Green.
Existing Homes Opportunities
20% of pre-1980 homes are well insulated
Air Sealing . . . & insulation More uniform temperature Increases comfort
Costs Energy costs increasing Increased retrofit costs are
often offset by increased savings
Tax credits and rebates
Source: 2007 Buildings Energy Data Book, Table 4.2.1., 2005 energy cost data
Whole-House Design
Design/Implement energy efficient solutions
Work through implementation issues Technical product/system designs Details Process (quality management)
Simulations/Analysis Cost optimization
Building America Integration
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Safety($-$$$$$)StructuralCombustionLeadAsbestosMoldMoisture
Building EnvelopeDurabilityMoisture Bulk Vapor DrainageAir Sealing Insulation
SystemsHeatingCoolingRight-SizedDucts VentilationDehumidification
Hot WaterPiping
AppliancesLightingMELs
RenewablesSolar Electric (PV)Wind
START HERE
COST
Whole-House Re-Design
ENERGY EFFICIENCY SAVINGS POTENTIAL
Montgomery County Habitat for Humanity
New Horizons for Remodeling
Constraints & Design Opportunities Durability Energy Efficiency
“Test-in” Data Identify products/methods
Details Documentation
“Test-out” Data Energy Savings Simulations Technical/professional development
List of EE Recommendations Moisture: Exterior grading & sump pump operation
Air Sealing Insulation Ventilation
Windows
System Evaluations HVAC Ducts Water Heating
Equipment Specifications Direct vent, minimum 92% AFUE gas furnaces 14.5 SEER cooling size in accordance with ACCA Manual J/S Programmable thermostats
List of EE Recommendations Ducts
Seal all ducts Relocate supply and return ducts to floor Return air paths for all rooms
Duct exhaust fans to the outdoors Kitchen Bath
MERV 8 minimum filtration
Hot Water & Water Distribution Direct vent/power vent water heaters Insulated hot water piping Low flow faucets, shower heads, and water closets
ENERGY STAR appliances ENERGY STAR lighting Construction Sequence
Clear Improvement: Wall Insulation
R 4.7 original to R 20 retrofit
Calculated Improvement
Wall U-value calculation Original Block Wall Original Remodeled Block Wall
Cavity Framing Isothermal Cavity Framing Isothermal
still air Interior film 0.68 0.68 0.68 0.68 0.68 0.68 sheetrock Interior covering 0.45 0.45 0.45 0.45 0.45 0.45
2x4 wall Framing/cavity R 13 4.2 8.772 1" foam Interior insulation 5 5 5
fir strips & air Framing/cavity R 1 0.9 0.975 4" block Block Wall 1.93 1.93 1.93 1.93 1.93 1.93 air gap Exterior air gap 1 1 1 1 1 1
brick façade Exterior covering 0.48 0.48 0.48 0.48 0.48 0.48 outside air Exterior film, winter 0.17 0.17 0.17 0.17 0.17 0.17
Isothermal Plane 4.7 R-value 19.5 R-value
Parallel Path 4.7 R-value 20.8 R-value
* R-values in hr ft∙ 2 °F/Btu∙
Other Wall Improvement Opportunities
Frame wall option 1: Add 1” exterior insulation
when siding is replaced R 11.8 to R 17.4
Frame Wall Option 2: Build 2x4 wall inside of
2x4 wall (both R 13) R 11.6 to R 20.2
Calculated Improvement
Wall U-value calculation Hathaway Addition Framed Wall Addition Remodeled Wall
Cavity Framing Isothermal Cavity Framing Isothermal
still air Interior film 0.68 0.68 0.68 0.68 0.68 0.68 sheetrock Interior covering 0.45 0.45 0.45 0.45 0.45 0.45
2x4 wall Framing/cavity R 13 4.2 8.772 13 4.2 8.772 OSB Exterior sheathing 0.5 0.5 0.5 0.5 0.5 0.5
1" foam Exterior rigid insulation 5 5 5 siding Exterior covering 0.61 0.61 0.61 0.61 0.61 0.61
outside air Exterior film, winter 0.17 0.17 0.17 0.17 0.17 0.17
Percent of Clear 77% 23% 77% 23%
Isothermal Plane 11.2 R-value 16.2 R-value
Parallel Path 11.8 R-value 17.4 R-value
* R-values in hr ft∙ 2 °F/Btu∙
Important Improvements
Moisture problems alleviated Crawlspace/room connection sealed Draftiness eliminated Ducts located to conditioned space Electrical upgrades simplified HVAC system size limited/smaller Energy bills reduced Comfortable
Cantilever Air Sealing Opportunity
• Remove soffit• Remove existing
insulation
• Add blocking• Foam seal floor
and wall• Install insulation
Split Level Knee WallAir Sealing Opportunity
Attic access unavailable, open wall, add air barrier and insulation
Energy Analysis
Whole-House Energy Use Estimates
House Identifier House Description Year BuiltA
Source Energy Savings Post-Retrofit
(Mbtu/yr)
Source Energy Consumption Reduction (%)
HERS Index
Estimate Notes Jeffry Street Masonry/Frame Split Foyer 1959 56.19 25.44% 96
Dauphine Street Masonry Split Foyer 1956 66.50 28.13% 103 C Denley Road Masonry Cape Cod 1950 41.23 17.71% 94 B Pittson Road Masonry/Frame Split Level 1958 78.30 27.90% 99
Goodhill Road Masonry Raised Ranch 1953 64.58 31.32% 86 Middle Road Frame Raised Ranch w/add 1946/ 42.14 18.23% 110 C
Farthing Drive Masonry Raised Ranch 1953 63.11 30.18% 85 Denley Place Masonry Raised Ranch 1950 86.67 38.36% 83 Harrell Street Masonry Raised Ranch w/add 1953/ 22.58 9.24% 90 D
Hathaway Drive Masonry Ranch w/add 1950/ 74.76 24.65% 100 Ivy Glen Road Frame Two-story (2nd Floor add.) 1946/ 107.20 39.12% 80 Napier Street Masonry Split Level 1955 97.39 33.21% 101
Average Savings
66.72 26.96%
A From tax records B HVAC equipment was upgraded in the Pre-Retrofit condition - 92% furnace, 62%PV DHW, 13 SEER A/C. C Old HVAC equipment was retained (Dauphine - 8 SEER / 71% furnace, DHW .50); (Middle - 9 SEER / 74% furnace, DHW 63%PV) D This house retained the same conditioned square footage in the pre- and post-remodel, but increased from 3 to 5 bedrooms and 1 to 2 baths. HVAC equipment was not upgraded; 13 SEER, 80% furnace, DHW switched from .53 gas to electric 80 gallon, .86 EF.
22www.toolbase.org
Greenbelt Homes, Inc.
Privately-owned cooperative housing development
1,600 units 1930’s-40’s
Pilot Project 7 buildings, 28
units 3 block 2 frame 2 brick
Pilot Program
Winter 2010 Pre-Retrofit baseline Install Monitoring Equipment Air infiltration Temperature/Humidity/
Energy Use Humidity
Summer 2011 Retrofit building envelopes
Winter 2011 Monitor envelope upgrade
Summer 2012 Retrofit HVAC
Winter 2012 Monitor upgrade package
Retrofit Solutions for Enhancing Energy Efficiency
Energy Savings: Household to National Comfort: Temperature swings to
consistency Moisture: Reduce potential problems Indoor Air: Controlled ventilation Technology: Options and performance Installation: Contractor training/QA Cost: Installation/operation/savings Value: Demonstrate values at sale
Resources
NAHB Research Center Corporate: www.nahbrc.com Technical: ToolBase www.toolbase.org
Remodeling Information & Case Study www.toolbase.org/remodel
Building America www.eere.energy.gov/buildings/building_america
Other Resources www.energysavers.gov www.energystar.gov/ia/partners/publications/pubdocs/
DIY_Guide_May_2008.pdf www.eeba.org/bookstore/cat-Energy_Efficiency-11.aspx http://dsireusa.org/
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Questions?
Thank You!
Amber WoodNAHB Research Center
Manager, Energy Programs
400 Prince George’s Blvd Upper Marlboro, MD 20774(direct) 301.430.6309 (fax) 301.430.6180
www.nahbrc.com