Economics of Passive Solar and Zero Energy Homes

Economics of Passive Solar
and Zero Energy Homes
Jeff Tiller, PE
™ ASU
Energy Center / Department of
Technology
™ Southface – North Carolina
™ [email protected]
™ 828-262-6355
Projected Residential Energy Use
NC Residential Energy Use (BBtu)
450,000
400,000
350,000
Solar
300,000
Wood
250,000
Coal
LPG
200,000
Kerosene
150,000
NaturalGas
Electricity
100,000
What can we do about this?
50,000
Global Insight Report on Energy Use in North Carolina, 2003
20
20
18
20
16
20
14
20
12
20
10
20
08
20
06
20
04
20
02
20
00
20
98
19
96
19
94
19
92
19
19
90
0
Final Preliminary Scenario
NC Residential Energy Use (BBtu)
450,000
400,000
350,000
300,000
250,000
200,000
New Home Savings
150,000
Existing Home Savings
Energy Efficient Scenario
100,000
50,000
20
20
18
20
16
20
14
20
12
20
10
20
08
20
06
20
04
20
02
20
00
20
98
19
96
19
94
19
92
19
19
90
0
Towards Zero Energy
‰
Step 1: High Efficiency
™
™
™
™
™
™
‰
Insulation systems; high efficiency windows
Energy Star
Air sealing
Systems Vision /
Duct sealing
Environments for Living
HVAC efficiency
NC HealthyBuilt Homes
Appliances and lighting
Indoor air quality / ventilation/ moisture control
Step 2: Passive Solar Design/
Natural Cooling Features
‰ Step 3: Solar Thermal
‰ Step 4: Green Building Features
‰ Step 4: Renewable Electricity
Livermore, CA
‰
3,070-square-foot
house
‰
A 3.6-kW PV array
‰
Solar hot water
‰
Night breeze
comfort system
‰
Low-E windows
‰
Fly ash concrete
Tucson, AZ
1,718 square feet
‰ 1kW PV system
‰ Solar hot water
‰ Low-e windows
‰ All homes in urban
subdivision exceed
model energy code
by 50%
‰
Califon, NJ
Year 1900 farmhouse
‰ 1,400 square feet
‰ 7.2 kW PV system
‰ Blown-in cellulose
‰ Insulated siding
‰
Fargo, GA
1,836 square feet
‰ Nonvented conditioned
crawl space
‰ 4 kW PV array
‰ Structural insulated
panels
‰ Recycled content decking
‰ Compact fluorescent
lights
‰ High performance HVAC
‰ Low 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, highperformance windows
Lakeland, FL
‰
1998 side-by-side comparison
‰
Twelve modules facing south:
2,700 W
‰
Six modules face west:
1,350 W
‰
The combined capacity:
4,050 W
‰
Annual energy use
™
Base home = 22,500 kWh/yr
™
PVRES =
1,500 kWh/yr
‰
Design features saved 70%
compared to base case
‰
PV system saved 22%
Systems Vision
‰
Project of Advanced Energy
‰ High performance affordable homes
‰ Three inspections required: framing,
insulation, final
‰ Ventilation and combustion safety
‰ Efficiency standard – Energy Star minimum
Passive Solar Design
‰ Most
affordable designs
™ Single
story
™ Limited window area
™ Simple appearance; low roof pitch
™ No attention to orientation
‰ Passive
solar design effort
™ Reorient
rooms and windows
™ Insulated slab floor
™ Insulation, air sealing, duct sealing details
™ High efficiency HVAC
Typical Design
LAUNDRY
DINING
BATH
BEDROOM
TV
SD
BATH
KITCHEN
UTILITY
CLOSET
‰ 1,147
HALL
CLOSET
SD
CLOSET
CLOSET
CLOSET
TV
SD
SD
BEDROOM
BEDROOM
CLOSET
LIVING
AREA
TV
1063 sq ft
sq ft
Passive Solar Option
Same
window
area
‰ 90 sq ft
face south
(8%)
‰ Savings:
‰ % heating
‰ % cooling
‰
LAUNDRY
DINING
BATH
BEDROOM
TV
SD
BATH
KITCHEN
UTILITY
CLOSET
HALL
CLOSET
SD
CLOSET
CLOSET
CLOSET
TV
SD
SD
BEDROOM
BEDROOM
CLOSET
LIVING
AREA
TV
1063 sq ft
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 Chapters
™ Redesigned
homes for Avery, Catawba Valley,
and Watauga
™ Also working with Asheville, North Charlotte,
Caldwell County and Alexander County
‰ Housing
™ NW
Authorities/ Other Groups
Housing Authority
™ Watauga Youth Build
™ Mountain Housing
NW Housing Authority
‰
Currently meeting Systems Vision
program guidelines
‰ Agreed to adopt new designs
‰ Agreed to meet NC HealthyBuilt Home
criteria
‰ First project: 18-home subdivision in
Jefferson, NC – The Oaks
Baby Cape Design
Zero Energy Plan design
‰
Catawba
Valley Habitat
for Humanity
‰ Project 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 ton
‰ Geothermal HVAC
‰ Typical cfm to
bedrooms – less than
75 cfm
‰ Most of ductwork – in
conditioned space
‰
Passive Solar Design
Energy Efficient
Appliances and Fixtures
Appliances and Lighting
‰
Thor washer-dryer combination
™ No
dryer vent, runs on 110 V, liquid water
drain
Energy Startm refrigerator and dishwasher
‰ Compact fluorescent lighting
‰ Low sone, effective Panasonic exhaust
fans
‰ Enthalpy Recovery Ventilation system
‰ Insulated window blinds
‰
Problems Along the Way
‰
South window design
™
Corner structure
™ Quest for high
SHGC; Window delivery
‰
‰
‰
Truss delivery
HVAC – loads
Solar water heating
™
Cost
™ Installation
‰
Photovoltaics
™
UL-listing
™ Interconnection
™ Meter Fee
™ The Freezer
Wall Framing Issue
Truss Issue
Solar Energy Systems
The Finished House
The power bills…
4.5 kW
Aug
kWh used
kWh produced
Net energy
Cumulative net energy
532
423
-109
-109
Sep
467
663
196
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 Economics
System materials
Installation
Total
Federal tax credit (30%)
Subtotal
NC tax credit (35%)
Net total
Annual savings
Payback period (years)
Mortgage pmts (20 yr, 7%)
$2,500
1,500
$4,000
1,200
$2,800
980
$1,820
300
6
$170/ yr
Photovoltaic Economics
Economic Analysis
System cost
Federal tax credit
Net cost
State tax credit
Net cost
Base credit rate
Downpayment
Points
Total Financing Cost
Mortgage Principal
Interest
Term
Annual Mortgage Payments
0.3
0.35
25,000
3,000
22,000
3,000
19,000
0.240
0.15
0.015
3,750
375
4,125
21,250
0.07
30
1,697
PV Economics
Income
Hours per day
kWh per day
kWh per year
Average avoided cost rate
NC GreenPower rate
Total income
4.5
20.25
7,391
0.0375
0.18
277
1,330
1,608
PV Renewable Electricity
System
‰
4.5 kW array designed to balance home’s
electricity demand
‰ Connected to grid via Duke Power
‰ Generator on NC GreenPower Program
Energy
Stars of
All Sizes