Heat Pump Water Heater (HPWH) Subcommittee

Christian DouglassRegional Technical Forum

June 18, 2015

2

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines for

small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

3

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines

for small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

4

Baseline Introduction

• HPWHs are treated as a Current Practice measure1 at the RTF• According to the RTF Guidelines, the baseline for a Current

Practice measure is defined by

1 For a definition of Current Practice, see Section 3.2.1 of the Guidelines.

“…the typical choices of eligible end users in purchasing new equipment and services at the time of RTF approval. The RTF estimates this baseline based on recent choices of eligible end users in purchasing new equipment and services. These choices may be inferred from data on shipments, purchases (equipment or services) or selected design / construction features.” (emphasis is mine)

5

Additional Context

• New DOE manufacturing standard (effective April 2015) sets very different minimum efficiency levels based on tank size

• Standard practice at the RTF has been to assume that manufacturer standards impact inventory immediately (i.e. no inventory lag)

Electric Resistance Water Heater (ERWH) can meet minimum Energy Factor for small tanks

Heat Pump Water Heater (HPWH) needed to meet minimum Energy Factor for large tanks.

6

Additional Context

• For reference, approx. 90% of the region’s residential stock of tanks is small by the DOE definition

Source: 2012 RBSA

5 7 20 30 40 45 50 54 60 65 75 82 88105

0%

10%

20%

30%

40%

50%

60%

70%

Tank Size (gallons)

Freq

uenc

y (In

clud

es S

F &

MH

)

Small Large

7

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines

for small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

8

Current Baseline Assumption

91%

9%

ERWHHPWH

• Important notes:– The current RTF measure includes small and large tanks in a single UES– I.e. this baseline represents the typical choices of end users purchasing any

size electric tank water heater (and assumes the 2015 standard is in effect)

This is the baseline that is used in the RTF’s current UES workbook that was passed at the November 2014 meeting.

9

Current Baseline: Explained• Starts with the following assumptions:

– Prior to the 2015 federal standard, eligible end users are choosing tank sizes in proportion to the RBSA stock

– HPWHs have zero market share

0-55 gals >55 gals0%

10%20%30%40%50%60%70%80%90%

100%

HPWHERWH

Tank Size

Num

ber o

f End

Use

rs C

hoos

ing

a Pa

rticu

lar C

onfig

urati

on

88.3%

11.7%

10

Current Baseline: Explained• Then assumes:

– After the 2015 standard, 75% of large tank end users will purchase large HPWHs, while 25% will purchase one or more small ER tanks

– The typical choices across all tank sizes will then be comprised of 9% HPWHs (11.7% * 0.75) and 91% ERWHs (88.3% + 11.7% * 0.25)

0-55 gals >55 gals0%

10%20%30%40%50%60%70%80%90%

100%

HPWH

ERWH

Tank Size

Num

ber o

f End

Use

rs C

hoos

ing

a Co

nfigu

ratio

n

88.3%

8.8%

91.2%

11

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines

for small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

12

Separate Baselines (and UESs) for Small, Large Tanks?

• Guidelines suggest that measure identifiers should be used where savings are not homogenous and differ by more than +/- 10%:"Measure identifiers define relatively homogenous applications of the measure with respect to savings or the method used in estimating savings. In addition… [the RTF will focus on] those identifiers that cause significant differences in savings (± 10%)...“ (emphasis is mine)

• If we think the savings of small and large tanks are very different, this argues for:1. Separate measure identifiers2. Separate baselines3. Separate UESs

13

Separate Baselines (and UESs) for Small, Large Tanks?

• How could we establish separate baselines and UESs for small and large HPWHs?– Contract Analyst Team (CAT) has hypothesized that existing tank size

along with purchased size might provide some insight into the baseline tank size "needed" by the homeowner

– If true, data on existing tank size could be used in conjunction with the purchased tank size to estimate the baseline, and therefore, savings

– For example,• Replace existing small tank with a new large tank savings• Replace existing large tank with a new large tank no savings (assume federal

standard forced the purchase)

• In looking at real BPA program data from prior to the 2015 standard, this hypothesis does not appear to hold

14

Investigation:BPA Program Data

Numbers in parentheses show sample size for each set of bars.

30 40 50 52 55 60 65 66 75 800%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

40

50

60

66

80

Existing Tank Size (gallons)

Freq

uenc

y

New Tank Size (gallons)

Other attributes such as tank price and availability may be

as important or more important than tank size in

purchasing decisions.

(7)

(34) (510)

(24) (9)

(27)

(22)

(18)

(4)

(41)

15

Conclusion

• At this time, CAT does not see evidence of, nor a way of identifying, separate markets (and baselines) for small and large tanks

• Therefore, proposal is to use a single baseline for a combined small tank / large tank UES– For now, consider this the best practical and reliable

estimation method – If regional researchers can identify a reliable alternative

that separates tank baselines, this can be reconsidered• Planning to discuss this with BPA and NEEA in fall of this year

16

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines

for small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

17

New Baseline Proposal

• Important note:– Similar to current baseline assumption with a couple of tweaks– Modifications to the current assumption are shown in red on next slides

94%

6.4%

ERWHHPWH

18

Proposed Baseline: Explained• Starts with the following assumptions:

– Prior to the 2015 federal standard, eligible end users are choosing tank sizes in proportion to the RBSA stock

– HPWHs have a small fraction of market share (from NEEA market data) for both small and large tanks

0-55 gals >55 gals0%

10%20%30%40%50%60%70%80%90%

100%

HPWHERWH

Tank Size

Num

ber o

f End

Use

rs C

hoos

ing

a Pa

r-tic

ular

Con

figur

ation

1.5%

88.8%

0.1%

9.6%

19

Proposed Baseline: Explained

• Then assume:– After the 2015 standard, 50% of large tank end users will

purchase large HPWHs, while 50% will purchase one or more small ER tanks• Why 50%? This ensures that the sensitivity to savings is less than

+/- 10% (turns out to be about +/- 7.5%)• If we choose a fraction at one of the extremes (i.e. 0% or 100%),

the impact to savings can be closer to +/- 15%

– The typical choices across all tank sizes will then be comprised of 6% HPWHs (1.5% + 0.1% + 9.6% * 0.5) and 94% ERWHs (88.8% + 9.6% * 0.5)

20

Discussion

• Does the subcommittee support the proposed recommendation on the baseline?

21

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines for

small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

22

Products in HPWH Market are a’ Changin

• CAT is planning to update HPWH savings in July to reflect new mix of products in the market

• How has the mix changed?– Largely, poorer performers are out (or heading out) and

better performers are in– E.g. Airgenerate ATI no longer being installed, older

generation GE unit being replaced with new generation unit

– First unit meeting NEEA Tier 3 efficiency levels now available

23

Products in HPWH Market are a’ Changin

• Lab-based results for new GE tank look promising

Older generation GE 50-gal tank.

New generation GE 50-gal tank running in default (Tier 2) mode.

New generation GE 50-gal tank running in Cold Climate (Tier 3) mode.

24

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines for

small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

25

Calibrating to the Real World

• Older GE tank, along with a few other tanks, was calibrated to field data to reflect “real world” performance– Documented in NEEA

Heat Pump Water Heater Savings Validation Study• Field data collected for about 100 total sites, or about 30-40 sites per

HPWH model studied• These sites were in addition to about 70 sites from other regional studies

– Resulting calibrated performance curves are currently used in SEEM

• New GE tank calibrated only to lab data

26

Calibrating to the Real World

• Is lab performance indicative of real world performance? What we know:– DOE draw patterns (currently used for lab tests) are

somewhat artificial and not reflective of in situ draw patterns

– Evidence that manufacturers “design to the tests” for higher rated COPs

– Ecotope compared lab calibrated results to field calibrated results for older GE tank - the result: significant underestimation of resistance element use and overestimation of heat pump use

27

Outline

• Baseline– Introduction and context– What is our current baseline assumption?– An investigation: do we need separate baselines for

small and large tanks?– New baseline proposal

• Calibration of New HPWHs– New products in market, including Tier 3– Calibrating to real world performance– A proposal for future calibration

28

Future Calibration: a Proposal

• The problem1. Existing suite of lab tests do not adequately predict field

performance2. Collection of field data for every new tank hitting the

market is neither feasible nor sustainable ($$)

• Our proposed solution: a hybrid approach1. Add an additional lab test to the existing suite which uses

“real world” water draw patterns collected from field data2. Calibrate performance characteristics (to be used for

savings estimation) to this test rather than DOE tests

29

Future Calibration: a Proposal

• Example of a field data-informed draw profile

30

Future Calibration: a Proposal

• The proposal must first be tested on units where we already have field data– Calibrated results from new lab test will be compared to calibrated

results from the original field study– Comparison will prove or disprove the validity of the proposed approach

• This is research, so CAT has added a section to the overall research strategy (see separate Word document)

• CAT plans to bring research strategy before the R&E Subcommittee in July

31

Discussion

• Thoughts on the proposed approach from a technical standpoint?

• Does the subcommittee support the proposal to add this calibration study to the overall research strategy for HPWHs?

32

Additional Slides

33

BPA Program Data: Existing Tank Size vs. New Tank Size, Shown in Pivot Table

Count of New unit size (gal) Column LabelsRow Labels 40 50 60 66 80 Grand Total30 7 740 1 30 1 1 1 3450 462 12 21 15 51052 24 2455 9 960 19 5 1 2 2762 1 165 19 1 1 1 2266 13 1 2 2 1875 2 2 480 32 3 6 4182 1 1 285 1 1 290 1 1120 1 1Grand Total 1 621 20 31 30 703

New Tank Size

Exis

ting

Tank

Siz

e