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