Field Experience with Ground-Source Heat Pumps in Affordable Low Energy Housing Daniel Ellis...
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Transcript of Field Experience with Ground-Source Heat Pumps in Affordable Low Energy Housing Daniel Ellis...
Field Experience with Ground-Source Heat Pumps in Affordable Low Energy Housing
Daniel EllisPresident
ClimateMaster, Inc.Oklahoma City, U.S.A.
Non-profit Christian housing ministryFounded in 1976
Has built 250,000 homes world-wideProviding over 1 million people with safe, decent, affordable shelter
3rd largest private homebuilder in USA5,000 homes per year in USA
Plus 20,000 homes per year in other countries
Not a give-away programVolunteer labor and donations reduce costs
Homeowners provide down-payment, interest-free mortgage payments, and sweat equity
COHFH Builder’s “Blitz” Week (June 2006)(1/3)
Monday 08:00 slab with GHX Friday 16:00 owner move-in
10 professional home builders each sponsored a separate house and constructed it from start to finish in 5 days!
SO HOW DID THEY DO IT?SO HOW DID THEY DO IT?
COHFH Builder’s “Blitz” Week (June 2006)(2/3)
Brute Force!Brute Force!
COHFH Builder’s “Blitz” Week (June 2006)(3/3)
Ongoing Partnership Formed in 2007
COHFH, GHP manufacturer, and local electric utility partner to make all COHFH homes low energy
Higher initial costs could not be passed on to homeowners due to COHFH cash flow considerations
COHFH is the mortgage lender
GHP manufacturer and electric utility agree to share initial cost difference over standard construction
Act of corporate stewardship
Gift of reducing energy consumption provides long-term benefits to the homeowners and to our environment
Provides valuable experience in unexplored segment of housing market
Partnership Goals
Install GHP systems in all COHFH homes
Reduce total energy demand of these homes to maximum reasonable extent
Using cost-effective and generally available measures
Track the energy consumption of the homesCollect monthly utility meter data to establish a baseline of actual performanceInstall a proportion of “smart” recording meters to collect detailed data on electric demand profiles
Demonstrate potential for zero energy homesBy integrating grid-tied solar PV systemInitial goal of zero peak demand and zero net GHP energylater goal of zero net total energy
Utilize project as a market transformation toolLarge-scale demonstration of affordable, low-energy housingRaise public and construction trade awareness, generate spin-off projects with other HFH affiliates, and attract additional COHFH funding
Exhaust Ai r
Supply Ai r Return Ai r
VentedUncondi tioned
Attic
GasFurnace
Attic Venti la tion
Attic Venti la tion
Outside Ai r
Exhaust Ai r
Supply Ai r Return Ai r
SealedAttic
Ground-Source
HeatPump
Dual Pane Clear
Dual Pane Low-ELow SHGC
400 ft. BoreUnder Slab
Internal Pump
A/CCoil
Flue
CombustionAi r
Condensing Uni t
So lar PV Array
IncandescentLighting
FlourescentLighting
Evolution of COHFH Homes
Standard Gas House
Energy Use: 252 kWh/(m2· yr)Energy Cost: $1,739 CO2 Emissions: 105 kg/(m2· yr)
Low Energy GHP + PV House
Energy Use: 52 kWh/(m2· yr)Energy Cost: $522 CO2 Emissions: 41 kg/(m2· yr)
COHFH Housing Characteristics (1/2)
Standard Standard Low Energy Low EnergyGas GHP GHP GHP + PV
Heating Gas GHP GHP GHPCooling Split A/C GHP GHP GHPHot Water Gas Storage Elec Storage1 Elec Storage1 Elec Storage1
Lighting Incandescent Incandescent Flourescent FlourescentAppliances Standard Standard Energy Star2 Energy Star2
Solar PV Array DC kW 2.3
Construction Wood Frame Wood Frame Wood Frame Wood FrameFloor Slab on Grade Slab on Grade Slab on Grade Slab on GradeAttic Vented Vented Sealed SealedInsulation Type Fiberglass Fiberglass Spray Foam Spray FoamAir Duct Location Attic Attic Attic AtticVentilation Spot Exhaust Spot Exhaust Central Supply Central Supply
1. GHP desuperheater assist
2. Energy Star appliances meet strict efficiency guidelines
House Type
COHFH Housing Characteristics (2/2)
Standard Standard Low Energy Low EnergyGas GHP GHP GHP + PV
Average Floor Area m2 110 110 110 110
U-value - Total Envelope W/(m2· K) 1.66 1.66 1.25 1.25U-value - Slab Perimeter W/(m2· K) 1.10 1.10 1.10 1.10U-value - Wall W/(m2· K) 0.35 0.35 0.35 0.35U-value - Flat Ceiling W/(m2· K) 0.19 0.19U-value - Sloped Roof W/(m2· K) 0.26 0.26U-value - Air Duct W/(m2· K) 0.95 0.95 0.71 0.71U-value - Window W/(m2· K) 2.84 2.84 1.99 1.99SHGC - Window 0.62 0.62 0.40 0.40Natural Air Change Rate - Htg 1/h 0.78 0.78 0.30 0.30Natural Air Change Rate - Clg 1/h 0.56 0.56 0.22 0.22Envelope Air Leakage Rate Untested Untested Tested TestedAir Duct Leakage Rate Untested Untested Tested Tested
Heating Load (-11°C, 21°C) kW 8.2 8.2 5.3 5.3Cooling Load (36°C, 24°C) kW 6.1 6.1 4.7 4.7Hot Water Load (55°C) kWh/yr 3200 3200 3200 3200Lighting Load kWh/yr 1753 1753 701 701Appliance Load kWh/yr 4667 4397 3518 3518
House Type
COHFH Hope Crossing Project(1/4)
COHFH Hope Crossing Project(2/4)
COHFH Hope Crossing Project(3/4)
COHFH Hope Crossing Project(4/4)
Average Metered Energy Consumption
0
10
20
30
40
50
Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07 Nov-07 Dec-07 Annual
kW
h/(
m2 ·
mo
)
0
50
100
150
200
250
kW
h/(
m2 ·
yr)
Standard Gas Homes - Electricity Use
Standard Gas Homes - Gas Use
Standard GHP Homes - Electricity Use
234
116
50% Reduction
Derivation of Htg & Clg Energy Consumption
0
5
10
15
20
25
-600 -500 -400 -300 -200 -100 0 100 200 300 400
Monthly Degree Days ( Basis 18°C, - DDH, + DDC)
No
rmal
ized
kW
h/(
m2 ·
mo
)
Std Home - GasEH = -0.0397· DDH
R2 = 0.895
Std Home - GHPEH = -0.0134· DDH
R2 = 0.781
Std Home - A/CEC = 0.0284· DDC
R2 = 0.890
Std Home - GHPEC = 0.0145· DDC
R2 = 0.886
49% Reduction
66% Reduction
Average Metered Energy Costs
$0
$100
$200
$300
$400
Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07 Nov-07 Dec-07 Annual
Mo
nth
ly C
ost
$-
$500
$1,000
$1,500
$2,000
An
nu
al C
ost
Standard Gas Homes - Electricity Cost at $0.088/kWh
Standard Gas Homes - Gas Cost at $0.045/kWh
Standard GHP Homes - Electricity Cost at $0.080/kWh $1,606
$1,023
36% Reduction
Energy Consumption Estimates
Benchmark hot water, lighting, and appliance loads for standard houses estimated using NREL methodology (Hendron, et al. 2004)
CFL lighting and Energy Star appliance adjustments made for low energy houses
Heating and cooling energy estimated using GeoDesigner software from ClimateMaster
Solar PV contribution estimated using PVWATTs software from NREL
Estimated Site Energy Consumption by End Use
252
119
27
48
16
42
0
112
2316 17 16
40
0
82
13 1021
6
32
0
52
13 1021
6
32
-30-50
0
50
100
150
200
250
300
Total Heating Cooling Hot Water Lighting Appliance Solar PV
kW
h/(
m2 ·
yr)
Std Home - GAS Std Home - GHP
LE Home - GHP LE Home - GHP + PV
Validation of Energy Consumption Estimates
252
112
233
106
234
116
0
100
200
300
Std Home - GAS Std Home - GHP
kW
h/(
m2 ·
yr)
Average Weather Year Estimate
Degree Day Adjusted Estimate
Actual Metered Consumption
Source Energy and C02 Emission Estimates
US national average factors for electricity and natural gas obtained from NREL (Deru and Torcellini 2006)
Includes power plant conversion, transmission, and distribution losses for electricity
Includes pre-combustion effects associated with extracting, processing, and delivering primary fuels to point of conversion in power plant
For natural gas includes both pre-combustion effects and on-site combustion emissions
Estimated Total Energy Consumption and Emissions
252
112
82
52
465
373
271
171
105
88
64
41
0
100
200
300
400
500
Std Home - GAS Std Home - GHP LE Home - GHP LE Home - GHP + PV
kW
h/(
m2 ·
yr)
0
25
50
75
100
125
CO
2 eq k
g/(
m2 ·
yr)
Site Energy
Source Energy
GWP Emissions
Planned Future Improvements
Advanced GHP with variable capacity and integrated full-condensing hot water modes
Zero-energy home using larger grid-connected PV array
Estimated Site Energy Consumption by End Use
82
13 10
21
6
32
0
67
118 10
6
32
0
37
118 10
6
32
-30
0
118 10
6
32
-67
-80
-60
-40
-20
0
20
40
60
80
100
Total Heating Cooling Hot Water Lighting Appliance Solar PV
kW
h/(
m2 ·
yr)
LE Home - GHP LE Home - Adv GHPLE Home - Adv GHP + 2.3 kW PV ZE Home - Adv GHP + 5.3 kW PV
Additional Investment and Annual Energy Cost Savings
Standard Standard Low Energy Low Energy Low Energy Low Energy Zero EnergyGas GHP GHP Adv GHP GHP Adv GHP Adv GHP
2.3 kW PV 2.3 kW PV 5.2 kW PV
Additional Investment3:
Heating and Cooling -$ 4,500$ 4,500$ 6,000$ 4,500$ 6,000$ 6,000$ Solar Photovoltaic -$ -$ -$ 15,000$ 15,000$ 30,000$ Insulation, Lighting, Appliance -$ -$ 2,500$ 2,500$ 2,500$ 2,500$ 2,500$
Total -$ 4,500$ 7,000$ 8,500$ 22,000$ 23,500$ 38,500$
Annual Energy Cost1,2:
Heating 596$ 127$ 69$ 60$ 69$ 60$ 60$ Cooling 270$ 155$ 101$ 76$ 101$ 76$ 76$ Hot Water 275$ 132$ 158$ 78$ 158$ 78$ 78$ Lighting 175$ 175$ 70$ 70$ 70$ 70$ 70$ Appliance 423$ 440$ 352$ 352$ 352$ 352$ 352$ Solar PV Contribution -$ -$ -$ -$ (228)$ (228)$ (636)$
Total 1,739$ 1,029$ 750$ 636$ 522$ 408$ -$
Annual Energy Cost Saving3 -$ 710$ 989$ 1,103$ 1,217$ 1,331$ 1,739$
1. based on electricity at $0.100/kWh for first 600 kWh/month, then $0.050/kWh winter and $0.090/kWh summer for all kWh/month over 600
2. based on natural gas at $0.045/kWh equivalent
3. Relative to Standard Gas Home
House Type:
Return on Investment vs. Standard Gas Home
$8,500$7,000
$23,500
$38,500
$4,500
$22,000
0
10,000
20,000
30,000
40,000
0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000
Annual Energy Cost Savings ($)
Ad
dit
ion
al
Inv
es
tme
nt
($)
LE Home - Adv GHP
LE Home - GHP + 2.3 kW PV
LE Home - Adv GHP + 2.3 kW PV
ZE Home - Adv GHP + 5.2 kW PV
ROI = 20%
ROI = 15%
ROI = 10%
ROI = 5%
ROI = 0%
Std Home - GHP
LE Home - GHP
Annual Fuel Escalation Rate 2%
Conclusions
Total site energy consumption reduction of 50-75%Using GHPs and low-energy construction techniques
50% reduction in metered energy was achieved using GHPs alone
1,100 tons of annual CO2 emissions avoidedCollective contribution of 240 low energy GHP homes in Hope Crossing as compared to standard gas homes
Not including the contribution of solar PV systems
Low energy GHP homes are cost-effectiveEven at standard builder pricing, the ROI is over 15% after tax
Concepts employed are generally available
Low energy demand makes solar PV more viableSmall array on first two PV homes will reduce peak demand to near zero on hot summer afternoons and produce enough annual power to completely operate the GHP system
Zero net energy is feasible, but not yet cost-effective
Thank You!