RTF: Deemed Measure Analysis:Ground Source Heat PumpsFinal Summary and Recommendation

April 5th, 2011

GSHP Deemed Measure Analysis Project Objectives Assumptions and Basecase GSHP Energy Modeling Methodolgy GSHP Sizing GSHP Costs SEEM Runs and Calibration ProCost Runs and Analysis Recommendations

RTF GSHP Deemed Measure Study Objectives

Subcommittee MembersDavid Baylon, Shawn Oram, Ben Larson, Poppy Storm- EcotopeTom Eckman – NW CouncilGillian Charles - NW CouncilAdam Hadley – Hadley EnergyWarren Cook - PECIDanielle Gidding – BPAGary Grayson – Idaho PowerTodd Greenwell - Idaho PowerJim Haberman - BPADavid Hales – WSU Energy OfficeMark Jerome – KAM Energy/Pacific Air ComfortMark Johnson – BPABruce Manclark – Delta TDavid Maul - Maul Energy AdvisorsJim Maunder - Ravalli Electric Andres Morrison – Ecos ConsultingGuy Nelson - UGWGNick O’Neil - Energy TrustBrady Peeks - NW Energy WorksDennis Rominger – PSE

Summary of Activities

Conference calls and Goto Meetings were setup with the Sub-Committee on the following dates.

1. GSHP Sub-Committee Kickoff Meeting: Jan. 6th, 20112. GSHP Measure Review and Research: Jan 25th 20113. GSHP SEEM Integration and Costs : Feb. 23rd, 20114. GSHP Draft Recommendations : Mar. 16th, 20115. GSHP RTF Presentations : April 5th, 2011

Review of Scope:

Update Ground Source Heat Pump (GSHP) measure definitions, energy savings, costs, cost-effectiveness, and status for GSHP measures for Single Family and Manufactured Homes.

GSHP Deemed Savings Sub-Measures GSHP upgrade from an ASHP PTCS Duct Sealing PTCS Cx, controls and sizing De-superheat for DHW

Note: GSHP is last measure in. PTCS duct sealing, Cx, controls and sizing are already present in the ASHP base.

Assumptions and Base-case

Typical GSHP System

Prototype Modeling

Four Prototype homes Manufactured home 1568sf Single Family 2200sf Single Family w/Bsmt 2688sf Large Single Family 5000sf (Non-Standard

Prototype)

3 Heating Zones, 3 Cooling Zones Heating, Cooling, and DHW impacts C/B Analysis (ProCost)

Systems AssumptionBasecase Systems Airside Source Heat Pump (HSPF 8.5, SEER 14) Electric DHW (0.90 EF) Retrofit, Fully Weatherized New Construction PTCS Duct Sealing, Cx, Controls and Sizing

Proposed Systems Water-to-Air Heat Pump ((COP 3.7 32F EWT, 18.2 EER 77F EWT)

w/ ECM Motor, CV, single stage compressor) GSHP sized to meet load at 25 deg F OSA Electric Resistance installed w/ and w/o DHW Desuperheater buffer tank Horizontal Closed Loop Focus (lowest cost loops)

GSHP Energy

Modeling Approach

Outline of Modeling Develop GSHP W:A Heat Pump into SEEM. Develop annual ground loop curve into

SEEM Develop De-Superheater Savings into SEEM Calibration with actual ground source heat

pump energy monitoring study performed in1996 on mulitple sites in MT.(Missoula GSHP Study: co-op Maunder 1996 )

Heat Pumps: Heating Capacity Capacity vs Entering Water Temp

(3-Ton CM Tranquility 20 with ECM fan)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

0 10 20 30 40 50 60 70 80 90 100

Entering Water Temp

ou

tpu

t (K

btu

/hr)

Heat Pumps: Heating Performance Climate Master Tranquility 20, ECM fan, COP Ratings

(EAT 60,65,70,75. Includes fan energy, no pump energy)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 20 40 60 80 100

Entering Water Temp(F)

CO

P

Ground Loop Curves Used

Tewtr = 27*sin(2pi / 8760 * hoy + 3.5) + 55.5

Tewtr = 22*sin(2pi / 8760 * hoy + 3.5) + 55.5

Tewtr = 17*sin(2pi / 8760 * hoy + 3.5) + 55.5

GSHP Sizing &

Costs

System Sizing Assumptions Base-Case: ASHP sized to meet load at 30 deg OSA temp. Proposed: GSHP sized to meet load at 25 deg OSA and 30

degree EWT. Ground Loop is sized using IGSHPA’s CLGS program.

Inputs: 1. Full Load Hours: (Total BTU’s)/(Heat Pump

Capacity) (Used SEEM for BTU’s)

2. Desired Loop Design Temp = 30F EWT3. Ground Characteristics and Location4. Loop Type (Used 4 Pipe Trenches)

Outputs:Total Loop Length Calculated

GSHP Total Pipe Length Results (NC)Total foot of pipe in ground

depth 5' 5' 5' 8' HOUSE HZ1 HZ2 HZ3 HZ3

1568 964 2544 4572 29362200 1345 3226 5791 37292688 1313 3164 5716 36455000 1914 4552 8175 5293

Total Design Heat Load (Btu/hr)

  HZ1 HZ2 HZ3 1568 18,350 24,559 28,471 2200 23,562 31,881 37,070 2688 21,506 28,555 32,998 5000 39,292 48,275 55,778

GSHP Loop Size/Ton of House Load

Foot of pipe per ton of house load, NOT equipment load

depth 5' 5' 5' 8'

 HOUSE HZ1 HZ2 HZ3 HZ3

1568 630 1243 1927 1237

2200 685 1214 1875 1207

2688 733 1330 2079 1326

5000 633 1132 1759 1139

Example: 1568 house in HZ2 is 24,559 btu/hr peak load. Sizing selection is 2 ton of GSHP w/elec resistance and (4x) 600’ ground loops.

GSHP Installed Costs (inside only)

Heat Pump Size

All Inside Heat Pump, pumps,

piping w/ no ductsPrice Per

Ton2 $6,633 $3,3163 $7,319 $2,4404 $8,576 $2,1445 $9,556 $1,9116 $10,100 $1,683

GSHP Loop Costs

$1300 per 600’ loop and trench, all pricing scaled from this.

GSHP/ASHP System Costs (NC)

  GSHP 1 ASHP GSHP 2 ASHP GSHP 3 ASHP

 S.F. HZ1 HZ1 HZ2 HZ2 HZ3 HZ3

1568 $8,721 $5,273 $12,145 $5,273 $16,175 $5,273

2200 $9,890 $5,573 $13,965 $5,273 $19,095 $5,573

2688 $9,821 $5,573 $13,831 $5,573 $18,822 $5,573

5000 $12,094 $6,173 $17,810 $6,173 $25,150 $6,173

GSHP Incremental Costs (NC)

Desuperheat

$500 adder without preheat tank $1000 adder with preheat tank Range of DHW savings 800-2200 kwh

(only runs when heat pump runs).

Calibration

Missoula Study Calibration Source

SEEM GSHP Module Calibration Metered data on 19 houses with GSHPs: Missoula Electric

Cooperative GSHP Demonstration Project, 1996 Created SEEM runs based on reported insulation values

& floor areas. Two SEEM prototypes used (1344 over sealed crawl and 2688 basement) to match average floor area

Strategy:Match reported equipment output to SEEM equipment output

No heat pumps involved in this step – it validates the inputs only

Use validated inputs with GSHP modelMatched GSHP design: 45F loop (vertical bores in aquifer) Very little auxiliary heat reported so used 35F outside T lockout to limit aux heat use in simulationsNext step is to derate COP of SEEM GSHP to match those in 1996 study (3.72.5)Final piece is determining useable desuperheat energy (simply used a multiplier to derate SEEM output to match metered data accounting for COP differences)

Calibration ResultsMT

StudyN= 19

SEEM

Floor Area (ft^2) 1985 1949

Heat Pump Size (tons) 2.63 2.73

Equipment Heat Output (kWh) 12404 12644

GSHP+Aux (kWh) 5211 5479

Aux Heat (kWh) 222 301

Space Heating Savings (kWh) 7193 7165

Useable Desuperheat (kWh) 967 962

• Match is good. • No tweaks to set point or internal gains were made. Duct sealing was

reported so was used. No special infiltration measures used (0.35ACHn). • Weather file used was Missoula TMY3 but reported energy data was not

weather normalized. potential source of error. • But, graph in report shows mean daily temperature reported was slightly

higher than a “normal” year. “Normal” not defined.

SEEM Runs & Pro-Cost Runs

Weatherized SEEM/ProCost Results

New Construction SEEM/ProCost Results

Outline Spec & Recommendatio

ns

Outline Specs GSHP AHRI Rating Point (COP-3.7 at 32F EWT, EER-

18.2 at 77 deg F EWT) Ducted Ground Source Heat Pumps shall be sized to meet

load at 25 F OSA temp and assume 30 F incoming loop temps.

Ducted GSHP shall include resistance heat with lockout over 35 F OSA temps.

Ground Loops shall be designed for 30 deg entering water temps at peak using an IGSHPA recognized sizing program.

Loop pumps shall be sized no larger than 150 watts/nominal ton of heat pump.

Desuperheater require a preheat buffer tank with no heat installed in preheat tank.

Recommendations Revise all existing measures with results from

this analysis. Adopt Savings Numbers for GSHP List GSHP as NON-cost-effective deemed

measure. Ground Source Heat Pumps are NOT cost

effective over ASHP’s. B/C ratios with an electric furnace as the

basecase unlikely to change significantly Increase savings Increase incremental costs.

Discussion & Decisions