Evaluation of Energy Savings for Strip Curtains

Presented To RTF

Scott MoorePECI Sr. Engineer

June 2, 2009

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Presentation Overview

• Justification for laboratory testing

• Methodology for laboratory tests

• Review test results

• Discuss potential annual savings and BC ratios

• Provide overview of current CPUC/ ADM Associates strip curtain evaluation

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Justification For Laboratory Testing• All known savings results prior to 2007 were

calculations based on ASHRAE infiltration formulas

• BPA conducted field M&V testing in 2007– Pre and post strip curtain test runs– Inconsistent door open times between test runs– Energy data not normalized for weather or

differences in length of defrost– Inconclusive results– BPA conducted field M&V testing in 2007

• BPA and PECI concurred on laboratory testing to control variables

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PECI Test Overview

• Emerson Sidney, Ohio Test Laboratory

• Separate Low and Medium temperature tests

• 12 hour runs – Closed door– Open door with strip curtains– Open door without strip curtains

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Test Walk In Box / Condensing Unit

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Evaporator Coil Location

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Indoor Condensing Unit Location

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Average Medium Temp Run Conditions

• 38F internal temperature

• 74-75F D.B. / 61-63F W.B.

• 79-80F condenser air inlet

• 27.4 sq. ft door

• Open door 4 minutes every 2 hoursConsistent with BPA for auto closer / gasket / strip tests

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Average Low Temp Run Conditions

• -4F internal temperature

• 75-77F D.B. / 53-54F W.B.

• 80-82F condenser air inlet

• 27.4 sq. ft door

• Open door 4 minutes every 2 hoursConsistent with BPA for auto closer / gasket / strip tests

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Medium Temp Emerson Results(12 hr. test data converted to 24 hr. results)

Parameter Door Closed Door Openings

w/Strip CurtainsDoor Openings w/o Strip

Curtains

Condensate Drainage per Day (oz) 43.6 68 128.6

Duty Cycle (%) 6.9% 8.0% 9.4%

Average Power (Watts) 783.8 821.2 944.1

24 Hour Energy (kW-hrs) 18.8 19.7 22.7

Energy increase per day (kW-hrs) -0.9 Baseline 3

% energy increase -4.6% Baseline 15.2%

Annual Energy Savings w/ curtains (kWh)   1095  

Annual Energy Savings Per Sq. Ft Door (kWh)

  40  

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Low Temp Emerson Results(12 hr. test data converted to 24 hr. results)

Parameter Door Closed Strip Curtain

 

No Strip Curtain

Condensate Drainage per Day (oz.)92 117.6 196.6

Duty Cycle (%)40.7 45.2 55.3

Average Power (Watts)2401.6 2567.9 3136.4

24 Hour Energy (kW-hrs)57.6 61.6 75.3

Energy increase per day (kW-hrs)-4 Baseline 13.7

% energy increase-6.5% Baseline 22.2%

Annual Energy Savings (kWh)  5001  

Annual Energy Savings per Sq. Ft. Door (kWh)   182.5  

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Application of Lab results for Utility Measure

• Unscaled

Variable = Door open time

• ScaledVariables = Door open time

Compressor system type and EER Climate zone

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Annual Energy Savings / Sq. Ft. Opening(Unscaled)

• Medium Temp:0.8 hr open (48 minute lab test): 40 kWh1 hr. open: 50 kWh2 hr. open: 100 kWh2.5 hr. open: 125 kWh3 hr. open: 150 kWh4 hr. open: 200 kWh

• Low Temp:

0.8 hr. open: 182.5 kWh1 hr. open: 228 kWh2 hr. open: 456 kWh2.5 hr. open: 570 kWh3 hr. open: 684 kWh4 hr open: 912 kWh

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Determination Of Potential Scaled Annual Savings For BPA Territory

• Determine door open time standard

• Adjust test results for system type, EER and annual outdoor ambient conditions– Multiplex system (FHP, FSP)– Single system (fixed head pressure)– Varying climate zones– Control systems

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Door Open Times

Logged data from 2007-2008 BPA Field tests for walk in box strip curtains and auto door closures:

– 18 logged boxes– Per day range: 0.6 hrs.- 5.8 hrs.– Per day average: 2.5 hours

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Compressor System Weighting% BPA Walk-in Load attached to System Type

System Type Low Medium

Integral 1% 1%

Multiplex 57% 59%

Stand Alone 42% 40%

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Final Lab Results Weighting Factors for Northwest

• Medium Temp: 77%*

• Low Temp: 82%*

*Accounts for population of different compressor system types, EER’s and climate zones

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Potential Savings*

• Medium Temp. Box Annual Savings:

kWh/sq.ft./hr * door open hours * weighting factor

= 50 * 2.5 * 0.77 = 96 kWh/sq. ft

• Low Temp. Box Annual Savings:

kWh/sq.ft./hr * door open hours * weighting factor

= 228 * 2.5 * 0.82 = 467 kWh/sq. ft

* Based on 2.5 hr. open/day/365days/yr.

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Potential Savings (Weighted by population of box type)

• PECI Grocer Smart ECM motor database– 73% Medium temp boxes– 27% Low temp boxes

96 kWh/sq. ft (med.) * 0.73 = 70.0 kWh

467 kWh/sq. ft. (low) * 0.27 = 126.0 kWh

= 196 kWh

Combined low/med weighted savings = 196 kWh/sq. ft.

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BC Ratio / TRC Levelized Cost Input

• $10.00 sq. ft. total 2008 installed cost

• $9.55 sq. ft. total deflated installed cost

• 4 year Measure Life

• No annual maintenance

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BC Ratio / TRC Levelized Cost*

Type B/C Ratio TRC Levelized Cost

Med. 2.1 11.8

Low 10 -9.2

Combo 4.2 -1.5

*$10.00/ sq. ft. total install cost, deflated to $9.55/ sq. ft.

* 4 Year Measure Life

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CPUC / ADM Study

• ADM Associates is lead contractor for strip curtain study for the CPUC

• ADM research concluded:– Previous savings numbers calculated by various

state utilities– Previous work paper savings based on

calculations using ASHRAE infiltration guidelines and formulas

– No field M&V or logging of door open times

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ADM Proposal For Analysis

• Domain of study– Type of business– Type of refrigeration unit– Geographical location of site

• Develop a site sample design– Paired study– With strip curtains– Without strip curtains

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ADM M&V Approach

• Use statistical model• Conduct tracer gas measurements of air infiltration• Calculate loads based on refrigeration system

weather dependant COP• Log system energy use• Conduct door monitoring with data loggers

– Number of openings– Length of openings

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Questions / Comments