Embed Size (px)
Citation preview
Economics of Passive Solar and Zero Energy Homes
Jeff Tiller, PEASU Energy Center / Department of TechnologySouthface – North [email protected]
Projected Residential Energy Use
Global Insight Report on Energy Use in North Carolina, 2003
NC Residential Energy Use (BBtu)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
2018
2020
SolarWoodCoalLPGKeroseneNaturalGasElectricity
What can we do about this?
Final Preliminary Scenario
NC Residential Energy Use (BBtu)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
2018
2020
New Home SavingsExisting Home SavingsEnergy Efficient Scenario
Towards Zero Energy
Step 1: High EfficiencyInsulation systems; high efficiency windowsAir sealingDuct sealingHVAC efficiencyAppliances and lightingIndoor air quality / ventilation/ moisture control
Step 2: Passive Solar Design/ Natural Cooling Features
Step 3: Solar ThermalStep 4: Green Building FeaturesStep 4: Renewable Electricity
Energy Star
Systems Vision / Environments for Living
NC HealthyBuilt Homes
3,070-square-foot house A 3.6-kW PV arraySolar hot waterNight breeze comfort systemLow-E windowsFly ash concrete
Livermore, CA
Tucson, AZ1,718 square feet1kW PV systemSolar hot waterLow-e windowsAll homes in urban subdivision exceed model energy code by 50%
Califon, NJYear 1900 farmhouse1,400 square feet7.2 kW PV systemBlown-in celluloseInsulated siding
Fargo, GA1,836 square feet Nonvented conditioned crawl space4 kW PV arrayStructural insulated panelsRecycled content deckingCompact fluorescent lightsHigh performance HVACLow E windows
New Smyrna, FL
A duplex with 1,736 sq ft of living area for unit 1 and 1,224 sq ft of living area for unit 2. 28 amorphous silicon modules bonded to the metal roof panels Light-colored exterior walls Large overhangs and porches help to shade the double-glazed, high-performance windows
1998 side-by-side comparisonTwelve modules facing south: 2,700 W Six modules face west: 1,350 WThe combined capacity: 4,050 WAnnual energy use
Base home = 22,500 kWh/yrPVRES = 1,500 kWh/yr
Design features saved 70% compared to base casePV system saved 22%
Lakeland, FL
Systems Vision
Project of Advanced Energy High performance affordable homesThree inspections required: framing, insulation, finalVentilation and combustion safetyEfficiency standard – Energy Star minimum
Passive Solar Design
Most affordable designs Single storyLimited window areaSimple appearance; low roof pitchNo attention to orientation
Passive solar design effortReorient rooms and windowsInsulated slab floorInsulation, air sealing, duct sealing detailsHigh efficiency HVAC
Typical Design
1,147 sq ftTV
TV
TV
SD
SD
SD
SD
BEDROOMBEDROOM
LIVINGAREA
1063 sq ft
BEDROOM
CLOSET
CLOSET
CLOSET
HALL
BATH
BATH
CLOSET
CLOSET
UTILITY
CLOSET
DINING
KITCHEN
LAUNDRY
Passive Solar Option
Same window area90 sq ft face south (8%)Savings:% heating% coolingTV
TV
TV
SD
SD
SD
SD
BEDROOMBEDROOM
LIVINGAREA
1063 sq ft
BEDROOM
CLOSET
CLOSET
CLOSET
HALL
BATH
BATH
CLOSET
CLOSET
UTILITY
CLOSET
DINING
KITCHEN
LAUNDRY
Passive vs. Non-Passive Plan
Available on-line at www.ncenergystar.org
Affordable Passive Solar Plans
Affordable Passive Solar Plans
Enthusiastic Response
Habitat for Humanity ChaptersRedesigned homes for Avery, Catawba Valley, and WataugaAlso working with Asheville, North Charlotte, Caldwell County and Alexander County
Housing Authorities/ Other GroupsNW Housing AuthorityWatauga Youth BuildMountain Housing
NW Housing Authority
Currently meeting Systems Vision program guidelinesAgreed to adopt new designsAgreed to meet NC HealthyBuilt Home criteriaFirst project: 18-home subdivision in Jefferson, NC – The Oaks
Baby Cape Design
Zero Energy Plan design
Catawba Valley Habitat for HumanityProject in Hickory, NC
The Zero Energy Home
Insulated Foundation
Framing
Framing Details
Framing Details
Icynene Insulation
Truss Design
HVAC System
Total cooling load –less than 1 tonGeothermal HVACTypical cfm to bedrooms – less than 75 cfmMost of ductwork – in conditioned space
Passive Solar Design
Energy Efficient Appliances and Fixtures
Appliances and Lighting
Thor washer-dryer combinationNo dryer vent, runs on 110 V, liquid water drain
Energy Startm refrigerator and dishwasherCompact fluorescent lightingLow sone, effective Panasonic exhaust fansEnthalpy Recovery Ventilation systemInsulated window blinds
Problems Along the Way
South window designCorner structureQuest for high SHGC; Window delivery
Truss deliveryHVAC – loadsSolar water heating
CostInstallation
PhotovoltaicsUL-listingInterconnectionMeter FeeThe Freezer
Wall Framing Issue
Truss Issue
Solar Energy Systems
The Finished House
The power bills…
4.5 kWAug Sep
kWh used 532 467kWh produced 423 663Net energy -109 196Cumulative net energy -109 87
The power generation bills”…
NC GreenPower Payment
Solar Water Heating
Installed: $4,500 (maxes out tax credit)Decided to hire installer (or self install)Three bids (Two collectors, 80-gallon storage with built-in heat exchanger, pumps, all key parts)
$2,900$2,500$2,200
Solar Hot Water EconomicsSystem materials $2,500Installation 1,500Total $4,000Federal tax credit (30%) 1,200Subtotal $2,800NC tax credit (35%) 980Net total $1,820Annual savings 300
Payback period (years) 6Mortgage pmts (20 yr, 7%) $170/ yr
Photovoltaic EconomicsEconomic AnalysisSystem cost 25,000 Federal tax credit 0.3 3,000 Net cost 22,000 State tax credit 0.35 3,000 Net cost 19,000 Base credit rate 0.240
Downpayment 0.15 3,750 Points 0.015 375 Total Financing Cost 4,125 Mortgage Principal 21,250 Interest 0.07 Term 30Annual Mortgage Payments 1,697
PV Economics
IncomeHours per day 4.5kWh per day 20.25kWh per year 7,391
Average avoided cost rate 0.0375 277 NC GreenPower rate 0.18 1,330 Total income 1,608
PV Renewable Electricity System
4.5 kW array designed to balance home’s electricity demandConnected to grid via Duke PowerGenerator on NC GreenPower Program
Energy Stars of All Sizes
