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SWEEP Workshop on Zero Energy Homes in New Mexico:
Introduction to Near-Zero Energy Homes
Rob Hammon, Ph.D.
What is Building America (BA)?
• National Department of Energy program– Marketable, cost-effective net-Zero Energy
Homes (ZEHs) by 2020• Today’s near-Zero Energy Homes
– Advanced energy efficiency – Solar energy technologies– Utility bill reductions >50%– Goal: 40%-70% energy efficiency savings
plus savings from solar
What is BIRA?
• Building Industry Research Alliance– Collaborative team; over 100 industry
partners– Led by ConSol
• One of seven Building America teams– Only West Coast team– Only team that is part of the building industry
Building America Research Process
House designs are compared to the “BA Benchmark” to predict savings level
Benefits of Building ZEHs with BA
• Monetary benefits– Cost savings from making the best materials
and equipment choices – Reduced risks, increased productivity, and
fewer callbacks – Sells faster than competition
• Additional benefits– Competitive advantage in the marketplace – Customer satisfaction and referrals– Beneficial to the environment
Albuquerque, New Mexico – Building America’s Mixed Dry Climate Zone
Pathway to ZEH in the Mixed Dry Climate ZoneM
ortg
age
+ U
tiliti
es ($
/mth
)
Source Energy Savings (%)
0
45
90
135
180
225
270
315
360
405
450
0 10 20 30 40 50 60 70 80 90 100
What features are currently being used?**based on 2003 IECC standards
2003 IECC Achieves 30% Savings
Current Building America goal: 50% energy efficiency savings
What can be done to improve efficiency?
• Increased wall insulation• Increased ceiling insulation• Adding a radiant barrier• Better sealing for a tighter envelope• Improved windows (U-value & SHGC)• Increased fluorescent lighting• High efficiency heating and cooling systems• Improved water heater• Improved duct insulation
Standard (30%) 40% Features Comparison
Standard (30%) 50% Features Comparison
Savings Levels at 40% and 50%
HERS Index Comparison
• Features providing 50% savings compared to the Building America Benchmark =64 HERS in Albuquerque, NM
• 50% savings + solar domestic hot water =60 HERS in Albuquerque, NM– NM Residential Sustainable Building Tax
Credit
Options to Further Improve Savings
• OVE/External Insulation/SIP walls
• MELs Reduction• Geothermal heat
pump– Trench/bore system– Water main system
• Solar– Passive heating– Hot water– Photovoltaics (PV)– PVT
OVE Walls (Optimum Value Engineered)
Uses engineering principles to minimize material usage while meeting model building code structural performance requirements
Less framing provides room for more insulation
External Foam Insulation
• Provides more R-value per inch than batts• Acts as a thermal break between studs and outside air
SIPs (Structural Insulated Panels)
MELs Reduction (Misc. Electric Loads)
• Feedback display• “Green switch”• “Smart strip”• Efficient electronic
devices (TVs, etc.)
Geothermal Heat Pump
Bore (vertical) system
Trench (horizontal) system
Benefits• Heat & cool savings up to 70%
• Lower install costs
• Lower maintenance costs
• Reduced pumping
• Reduces mechanical space
• No roof penetrations
• No combustion
• Longer system life
• Provides source of revenue
• Flexible & easily expandable
• Uses GeoExchange technology
Green Inq
Financial Benefits
• WaterGrid utility owned, installed and maintained
• No first cost to developer/owner• No water supply system costs• No wastewater system costs • No HVAC/DHW system costs • Lower user energy costs• Secondary treatment for use on-site and off-site
(parks, etc.)• Owner/user pays metered water use rate or a
flat fee to utility
Passive Solar Heating/Cooling
• Window orientation• Overhangs• Shading
– Landscaping– Exterior– Interior
• Mass• Controls (night
cooling)
SDHW (Solar Domestic Hot Water)
Can be implemented in mixed climates using an indirect system with propylene glycol
PV Panels (Photovoltaic)
May not be cost effective for the homeowner unless combined with efficiency measures
BIPV (Building Integrated) shown here
PVT (PV-Thermal)
Utilizes previously wasted heat generated by PV system
PVT (PV-Thermal)
ZEH Example
Includes:• SIPs walls• Geothermal
heat pump• PVT• 25%
reduction in MELs
ZEH Cost Effectiveness
• 50% efficiency measures– Currently developing cost effective strategies
with builders in the Mixed Dry Climate Zone• PV/PVT Systems
– Can be cost effective when combined with efficiency measures and available incentives
• Other advanced systems– May not be cost effective currently but will be
soon as energy costs continue to rise and mature market costs develop
Do ZEH Communities Really Work?Building America Case Studies
Climate: Hot Mixed/DryBuilder/Developer:
•Premier Homes
Community & Location:•Premier Gardens•Sacramento, CA
Number of Homes:•95 Total
Unique Elements of Project:•First standard ZEH community in Sacramento•100% solar PV•59% savings with PV•Built in 2004
BA Savings: 38%
Premier Gardens
Side-By-Side Developments
Near-ZEH Control
Side-By-Side Developments
Near-ZEH(60% Whole House Energy Savings)
SMUD Advantage(30% Cooling Reduction)
vs.
Energy Efficiency Features
Demographics
• Similar size and price• Contemporaneous sales• Near-ZEH
– More-experience buyers– More educated– Did more research prior to buying
• Control– Larger families (larger bedrooms)– More wage-earners (2-3/household), more income
Actual vs. Predicted Electricity Use (Revised)
No East , Eleven South , And Seven West
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
12am 1am
2am
3am
4am
5am
6am
7am
8am
9am
10am
11am
12am 1pm
2pm
3pm
4pm
5pm
6pm
7pm
8pm
9pm
10pm
11pm
Kw
New Avg Net Grid Load (E2W,W,S)
Previous Avg Net Grid Load (E,S,W)
Average of Non-ZEH Net Grid Load (kW)
Avg of PV Pwr (W,S)
Avg Gross loads (Kw)
-0.3 kW; 119%
0.86 kW; 67%
1.3 kW; 55%
2.9 kW
1.6 kW
20:45
19:45
Peak Reduction from EE & PV
Climate: Hot Mixed/DryBuilder/Developer:
•Treasure Homes
Community & Location:•Fallen Leaf at Riverbend•Natomas, CA
Number of Homes:•32 Total
Unique Elements of Project:•100% solar PV•57% savings with PV•Beutler SmartVent Fresh Air system•Built-out in 2007
BA Savings: 42%
Energy Efficiency Features
• R-38 attic insulation• R-13 fiberglass batts
+ 1” EPS foam• 3.1 SLA infiltration• Dual pane vinyl-frame
windows• Engineered HVAC
system– 90% AFUE furnace– 13 SEER A/C with
thermal expansion valve (TXV)
• R-4.2 buried ducts with tight duct and ACCA Manual D
• 0.82 EF tankless water heater and R-4 insulation on all trunk lines
• 100% fluorescent lighting
• Gas dryer stub provided
Renewable Energy Feature
2.0 kW PV system by BP Solar
Energy Cost ComparisonTreasure vs. Cresleigh Monthly Electricity Bills
$0.00
$20.00
$40.00
$60.00
$80.00
$100.00
$120.00
$140.00
Treasure Homes $34.37 $28.84 $26.88 $38.04 $52.72 $36.33 $34.59 $20.04 $16.83 $20.11 $32.21 $52.03 $53.77Cresleigh Homes $71.14 $66.10 $46.41 $67.45 $70.36 $62.77 $52.50 $47.46 $53.63 $64.49 $101.55 $96.43 $124.57
Avg. Mo. Bill Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07
Total Annual Electricity Bill:
Treasure Homes $412.38Cresleigh Homes $853.73
Energy Cost Savings
Assumes $1.00/therm and $0.08/kWh
Annual Mortgage CostAssumes 7% mortgage over 30 years
Cost Effective Analysis
Impact on PeakPremier vs. Cresleigh vs. Treasure Net Load, July 2007
-1
-0.5
0
0.5
1
1.5
2
2.5
12AM
1AM
2AM
3AM
4AM
5AM
6AM
7AM
8AM
9AM
10AM
11AM
12PM
1PM
2PM
3PM
4PM
5PM
6PM
7PM
8PM
9PM
10PM
11PM
kW Average of Premier Net Grid Load (kW) (18 home sample)
Average of Power Produced by Premier PV (kW)
Average of Cresleigh Net Grid Load (kW) (18 home sample)
Average of Treasure Net Grid Load (kW) (6 home sample)
Average of Power Produced by Treasure PV (kW)
Climate: Hot Mixed/DryBuilder/Developer:
•Grupe Homes
Community & Location:•Carsten Crossings•Rocklin, CA
Number of Homes:•144 Total
Unique Elements of Project:•Strong focus on sales and marketing •Courtesy of The Grupe Company and Davis Energy
Group
Efforts Necessary for Success
Courtesy of The Grupe Company and Davis Energy Group
Efforts Necessary for Success: Sales Training
Courtesy of The Grupe Company and Davis Energy Group
Efforts Necessary for Success: Sales Displays
Courtesy of The Grupe Company and Davis Energy Group
Baseline Absorption
Courtesy of The Grupe Company and Davis Energy Group
Sales Acceleration
Courtesy of The Grupe Company and Davis Energy Group
Adjusted Baseline Absorption
Courtesy of The Grupe Company and Davis Energy Group
Sales to Date
Courtesy of The Grupe Company and Davis Energy Group
Absorption Rate
Courtesy of The Grupe Company and Davis Energy Group
Results
Courtesy of The Grupe Company and Davis Energy Group
Results
Courtesy of The Grupe Company and Davis Energy Group
Thank You!
Questions?
Rob Hammon, Ph.D.Principal, ConSol