strip curtains for refrigerated walk-in boxes michele friedrich, pe – sr. engineer eric mullendore...
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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
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