Strip Curtains for Refrigerated Walk-in Boxes

Michele Friedrich, PE – Sr. Engineer

Eric Mullendore – Energy Analyst

PECI

8/3/2010

Purpose

Approval for new deemed measures for retrofitting strip curtains to walk-in coolers and freezers

Agenda

Proposed Measures

How do they save energy?

CPUC EM&V Report

Adapting savings for PNW

Costs

Effective Useful Life/Persistence

Program Specifications

Conclusions

Proposed Measures

Measure Application

Energy Savings (kWh/ ft2) EUL

Measure Cost ($/ ft2)

Benefit Cost Ratio

Strip Curtains- Supermarket Freezer 443 4 $9.77 18.8

Strip Curtains- Supermarket Cooler 103 4 $9.77 4.4

Strip Curtains- Convenience Store Freezer 30 4 $9.77 1.3

Strip Curtains- Convenience Store Cooler 21 4 $9.77 0.9

Strip Curtains- Restaurant Freezer 134 4 $9.77 5.7

Strip Curtains- Restaurant Cooler 25 4 $9.77 1.1

Strip Curtains- Rfg. Warehouse (MT) 350 4 $9.77 14.8

How do they save energy?

ASHRAE Refrigeration Handbook, 2006.

CPUC/ADM EM&V Report

Methodology

1. Measured the infiltration rates using tracer gas

2. Measured temperatures, relative humidities and door open times with loggers

3. Calculated annual kWh savings using data above as inputs into an hourly bin model

Commercial Facilities Contract Group: 2006-2008 Direct Impact Evaluation, Study ID: PUC0016.01; Prepared by ADM Associates, Inc. et al. February 2010.

CPUC/ADM Report Results

 

Average Evaluated

Energy Savings (kWh/ft2)

Standard Deviation of

Savings (kWh/ft2)

Relative Precision at

90% CI

Supermarket Freezer 409 237 32%

Supermarket Cooler 159 57 16%

Convenience Freezer 16 18 44%

Convenience Cooler 14 27 43%

Restaurant Freezer 77 152 73%

Restaurant Cooler 18 13 25%

Refrig. Warehouse- MT 177 116 29%

Adapting Results for PNW

• Adjust for EER values found in PNW climate zones and system types*

• Adjust baseline barrier efficacy to reflect program design

*EER and FLH values derived from DOE2.2R runs for various system types in PNW climate zones.

Energy Savings AssumptionsDelta

Efficacy(Proposed)

EER(Proposed)

0.88 4.5

0.88 10.3

0.83 4.0

0.79 9.9

0.81 3.9

0.80 9.8

0.89 10.3

 Minutes

Door Open/Day

Delta Temp (ºF)

Delta Efficacy (ADM)

Nominal EER

(ADM)

Supermarket Freezer 102 58 0.88 5.1

Supermarket Cooler 132 34 0.88 8.5

Convenience Freezer 9 57 0.53 5.1

Convenience Cooler 38 31 0.45 8.5

Restaurant Freezer 38 58 0.55 5.1

Restaurant Cooler 45 33 0.47 8.5

Warehouse MT 494 32 0.35 5.1

Baseline Efficacy Adjustment

 

Baseline Efficacy (ADM)

Baseline Efficacy

(Proposed)

Post Efficacy (Both)

Savings Using ADM

∆ Efficacy

Savings Using

Proposed ∆ Efficacy

Supermarket Freezer 0.00 0.00 0.88 409 409

Supermarket Cooler 0.00 0.00 0.88 159 159

Convenience Freezer 0.30 0.00 0.83 16 24

Convenience Cooler 0.34 0.00 0.79 14 25

Restaurant Freezer 0.26 0.00 0.81 77 109

Restaurant Cooler 0.33 0.00 0.80 18 30

Warehouse Cooler 0.54 0.00 0.89 177 451

Energy Savings Calculations

1000EER

QkW cooling

FLHkWkWh

retrofit-postbaseline kWhkWhkWh

Energy Savings Calculations

where, I = refrigeration load from infiltration when door is open, Btu/hrDt = doorway open-time factorDf = doorway flow factorE = barrier efficacy

E)(1DDIQ ftCooling

Comparison of Methodologies

 ADM

Report (kWh/ft2)

ASHRAE Equation w/

Metered Values (kWh/ft2)

ASHRAE Equation w/

Proposed Values (kWh/ft2)

Supermarket Freezer 409 409 443

Supermarket Cooler 159 159 103

Convenience Freezer 16 16 30

Convenience Cooler 14 14 21

Restaurant Freezer 77 77 134

Restaurant Cooler 18 18 25

Refrigerated Warehouse 177 177 350

Costs

Installed Cost: $9.77/ sq ft

• Average from 20 projects in the PNW

• Represents pricing of 7 trade allies

• Projects ranged from 1 to 8 walk-in doors

Effective Useful Life

4 years

• Value recommended by CALMAC*

• ODOE estimates 5 years‡

• Supported by program design

*California Measurement Advisory Committee Public Workshops on PY 2001 Energy Efficiency Programs. September 2000, p. 60.

‡SEED Guidelines, Appendix J.

Persistence Assured

SDG&E Persistence Assured Strip Curtain Program

• Implemented by PECI (2006-2008)

• Annual site inspection and maintenance

• Failure to persist resulted in rebate ‘clawback’

Persistence Results

Initial 2 Year 4 Year

Participation Persistence Persistence*

Sites: 405 95% 75%

Doors: 902 96% 82%

*Not all sites have been reviewed for 4 year persistence. Values displayed in this column represent the 81% of the sites verified to date.

Program Specifications

• Must install Strip Curtains where no infiltration barriers are currently in use

• Claimed savings and rebate value will vary by site type

• Program will track and report persistence

Conclusion

PECI seeks approval for the following deemed measures:

Measure ApplicationEnergy

Savings (kWh/ ft2) EUL

Measure Cost ($/ ft2)

Benefit Cost Ratio

Strip Curtains- Supermarket Freezer 443 4 $9.77 18.8

Strip Curtains- Supermarket Cooler 103 4 $9.77 4.4

Strip Curtains- Convenience Store Freezer 30 4 $9.77 1.3

Strip Curtains- Convenience Store Cooler 21 4 $9.77 0.9

Strip Curtains- Restaurant Freezer 134 4 $9.77 5.7

Strip Curtains- Restaurant Cooler 25 4 $9.77 1.1

Strip Curtains- Rfg. Warehouse (MT) 350 4 $9.77 14.8