Supermarket Refrigeration Codes and Standards Enhancement ...
Supermarket Refrigeration Codes and Standards Enhancement Initiative (CASE) Pacific Gas and Electric Company March 17, 2011 TABLE OF CONTENTS 1. Purpose ........................................................................................................................ 7 2. Overview ....................................................................................................................... 9 3. Methodology............................................................................................................... 18 3.1 Supermarket Prototype Definitions ..........................................................................................18 3.2 Energy Analysis and Cost Effectiveness Methodology ...........................................................19 3.3 Direct Refrigerant Emissions Calculations...............................................................................20 3.3.1 Base case refrigerant charge description............................................................................21 3.3.2 Direct emissions methodology ...........................................................................................21 3.4 Acceptance Testing...................................................................................................................22 3.5 Stakeholder Meeting Process....................................................................................................22 4. Analysis and Results ................................................................................................. 23 4.1 Floating Head Pressure .............................................................................................................24 4.1.1 Analysis results by climate zone ........................................................................................25 4.1.2 Refrigerant charge analysis ................................................................................................26 4.2 Condenser Specific Efficiency .................................................................................................28 4.2.1 Incremental analysis results ...............................................................................................31 4.2.2 Analysis of results by climate zone ...................................................................................32 4.3 Floating Suction Pressure .........................................................................................................34 4.3.1 Analysis results by climate zone ........................................................................................35 4.4 Mechanical Subcooling ............................................................................................................36 4.4.1 Analysis results by climate zone ........................................................................................36 4.5 Liquid-Suction Heat Exchangers ..............................................................................................37 4.5.1 Analysis results by climate zone ........................................................................................38 4.6 Display Case Lighting Control .................................................................................................44 4.6.1 Analysis results by climate zone ........................................................................................45 4.7 Prohibit Open Upright Frozen Food Cases...............................................................................45 4.8 Walk-in Variable Speed Fan Control .......................................................................................47 4.8.1 Analysis results by climate zone ........................................................................................47 4.8.2 Rationale for classifying as reach measure ........................................................................48
Page 2 4.9 Refrigeration Heat Recovery ....................................................................................................49 4.9.1 Analysis results by climate zone ........................................................................................49 4.9.2 Refrigerant charge analysis ................................................................................................51 4.10 CO2 Secondary (indirect) or Cascade Cooling ......................................................................53 4.10.1 Configurations of secondary cooling ..............................................................................53 4.10.2 Analysis results by climate zone ....................................................................................56 4.10.3 Refrigerant charge analysis ............................................................................................56 5. Recommended Code Language ............................................................................... 59 Title 24 Draft Code Language ............................................................................................................59 6. Appendix A: Rejected Measures .............................................................................. 64 6.1 Evaporator Coil Specific Efficiency .........................................................................................64 6.2 Display Case LED Lights .........................................................................................................64 6.3 Night Covers on Open Display Cases ......................................................................................65 6.4 Prohibit Gas Defrost .................................................................................................................65 6.5 Glycol Secondary Loop (Indirect) System Configuration ........................................................66 7. Appendix B: System Schematics ............................................................................. 67 8. Appendix C: Base Case Facility Descriptions ......................................................... 81 9. Appendix D: Refrigeration Schedules and Equipment Sizing ............................... 91 9.1 Refrigeration Schedules ............................................................................................................91 9.2 Equipment Sizing per Climate Zone ........................................................................................93 10. Appendix E: Charge Size and Leak Rate Assumptions for Direct Emissions ...... 95 Summary of Information Obtained on Charge Size and Leak Rates .................................................95 Methodology for Developing Charge Size Assumptions .................................................................100 DX Systems ...................................................................................................................................100 Distributed and Secondary Loop Systems ....................................................................................101 Impact of the Condenser Type ......................................................................................................101 Methodology for Developing Leak Rate Assumptions ....................................................................101 Limitations and Considerations ........................................................................................................102 11. Appendix F: Wetbulb Sensitivity Study for Floating Head Pressure Measure ... 103 12. Appendix G: Databases from Savings By Design................................................. 104 12.1 Condenser Specific Efficiency ............................................................................................104 13. Appendix H: Secondary System Assumptions ..................................................... 108 14. Appendix I: Stakeholder List and Description of Feedback ................................. 111 15. Appendix J: Full Cost Results ................................................................................ 112 15.1 Floating Head Pressure........................................................................................................112 15.2 Condenser Specific Efficiency ............................................................................................117 15.3 Floating Suction Pressure ....................................................................................................122 15.4 Mechanical Subcooling .......................................................................................................127
2013 California Building Energy Efficiency Standards
March 17, 2011
Page 3 15.5 Walk-In Variable Speed Fan Control ..................................................................................132 15.6 Display Case Lighting Control ............................................................................................137 15.7 Refrigeration Heat Recovery ...............................................................................................142 15.8 Secondary (Indirect) Cooling ..............................................................................................147 15.9 Liquid-Suction Heat Exchangers ........................................................................................149 16. Appendix K: Glossary ............................................................................................. 154
2013 California Building Energy Efficiency Standards
March 17, 2011
Page 4 TABLE OF FIGURES Figure 1: Prototype supermarket summary ........................................................................................... 18 Figure 2: Size and system description for analysis prototypes ............................................................. 19 Figure 3: Base case charge size and leak rate assumptions .................................................................. 21 Figure 4: Legend for analysis results tables .......................................................................................... 23 Figure 5: Summary of ambient following control TDs for SCT control measure ................................ 25 Figure 6: Analysis results for floating head pressure............................................................................ 25 Figure 7: State-wide carbon savings results for floating head pressure................................................ 26 Figure 8: State-wide total savings results (including carbon) for floating head pressure ..................... 27 Figure 9: Condenser description for specific efficiency measure ......................................................... 28 Figure 10: Example condenser capacity and power versus speed ........................................................ 29 Figure 11: Condenser cost versus MBH capacity at specific-efficiency rating conditions .................. 30 Figure 12 Example of increasing condenser size and resultant specific efficiency .............................. 30 Figure 13: System energy usage and TDV energy cost versus specific efficiency .............................. 31 Figure 14: Preliminary condenser specific efficiency results ............................................................... 32 Figure 15: State-wide energy analysis summary for condenser specific efficiency measure............... 32 Figure 16: Analysis results for prototypes, system configurations, and condenser types with benefit/cost ratios less than 1 ......................................................................................................... 33 Figure 17: Suction group design SST and Base Case SST setpoints.................................................... 35 Figure 18: Statewide savings results for floating suction pressure ....................................................... 35 Figure 19: Statewide savings results for mechanical subcooling measure ........................................... 37 Figure 20: Suction line heat gain assumptions (MT systems) .............................................................. 38 Figure 21: Suction line heat gain assumptions (LT systems) ............................................................... 38 Figure 22: LSHX sizing assumptions for cost and performance .......................................................... 38 Figure 23: State-wide savings analysis for liquid-suction heat exchangers (MT Walk-Ins) ................ 39 Figure 24: State-wide savings analysis for liquid-suction heat exchangers (LT Walk-Ins) ................. 40 Figure 25: State-wide savings analysis for liquid-suction heat exchangers (MT display cases) .......... 40 Figure 26: State-wide savings analysis for liquid-suction heat exchangers (LT display cases) ........... 41 Figure 27: MT walk-in LSHX simulations with BCR
Page 2 4.9 Refrigeration Heat Recovery ....................................................................................................49 4.9.1 Analysis results by climate zone ........................................................................................49 4.9.2 Refrigerant charge analysis ................................................................................................51 4.10 CO2 Secondary (indirect) or Cascade Cooling ......................................................................53 4.10.1 Configurations of secondary cooling ..............................................................................53 4.10.2 Analysis results by climate zone ....................................................................................56 4.10.3 Refrigerant charge analysis ............................................................................................56 5. Recommended Code Language ............................................................................... 59 Title 24 Draft Code Language ............................................................................................................59 6. Appendix A: Rejected Measures .............................................................................. 64 6.1 Evaporator Coil Specific Efficiency .........................................................................................64 6.2 Display Case LED Lights .........................................................................................................64 6.3 Night Covers on Open Display Cases ......................................................................................65 6.4 Prohibit Gas Defrost .................................................................................................................65 6.5 Glycol Secondary Loop (Indirect) System Configuration ........................................................66 7. Appendix B: System Schematics ............................................................................. 67 8. Appendix C: Base Case Facility Descriptions ......................................................... 81 9. Appendix D: Refrigeration Schedules and Equipment Sizing ............................... 91 9.1 Refrigeration Schedules ............................................................................................................91 9.2 Equipment Sizing per Climate Zone ........................................................................................93 10. Appendix E: Charge Size and Leak Rate Assumptions for Direct Emissions ...... 95 Summary of Information Obtained on Charge Size and Leak Rates .................................................95 Methodology for Developing Charge Size Assumptions .................................................................100 DX Systems ...................................................................................................................................100 Distributed and Secondary Loop Systems ....................................................................................101 Impact of the Condenser Type ......................................................................................................101 Methodology for Developing Leak Rate Assumptions ....................................................................101 Limitations and Considerations ........................................................................................................102 11. Appendix F: Wetbulb Sensitivity Study for Floating Head Pressure Measure ... 103 12. Appendix G: Databases from Savings By Design................................................. 104 12.1 Condenser Specific Efficiency ............................................................................................104 13. Appendix H: Secondary System Assumptions ..................................................... 108 14. Appendix I: Stakeholder List and Description of Feedback ................................. 111 15. Appendix J: Full Cost Results ................................................................................ 112 15.1 Floating Head Pressure........................................................................................................112 15.2 Condenser Specific Efficiency ............................................................................................117 15.3 Floating Suction Pressure ....................................................................................................122 15.4 Mechanical Subcooling .......................................................................................................127
2013 California Building Energy Efficiency Standards
March 17, 2011
Page 3 15.5 Walk-In Variable Speed Fan Control ..................................................................................132 15.6 Display Case Lighting Control ............................................................................................137 15.7 Refrigeration Heat Recovery ...............................................................................................142 15.8 Secondary (Indirect) Cooling ..............................................................................................147 15.9 Liquid-Suction Heat Exchangers ........................................................................................149 16. Appendix K: Glossary ............................................................................................. 154
2013 California Building Energy Efficiency Standards
March 17, 2011
Page 4 TABLE OF FIGURES Figure 1: Prototype supermarket summary ........................................................................................... 18 Figure 2: Size and system description for analysis prototypes ............................................................. 19 Figure 3: Base case charge size and leak rate assumptions .................................................................. 21 Figure 4: Legend for analysis results tables .......................................................................................... 23 Figure 5: Summary of ambient following control TDs for SCT control measure ................................ 25 Figure 6: Analysis results for floating head pressure............................................................................ 25 Figure 7: State-wide carbon savings results for floating head pressure................................................ 26 Figure 8: State-wide total savings results (including carbon) for floating head pressure ..................... 27 Figure 9: Condenser description for specific efficiency measure ......................................................... 28 Figure 10: Example condenser capacity and power versus speed ........................................................ 29 Figure 11: Condenser cost versus MBH capacity at specific-efficiency rating conditions .................. 30 Figure 12 Example of increasing condenser size and resultant specific efficiency .............................. 30 Figure 13: System energy usage and TDV energy cost versus specific efficiency .............................. 31 Figure 14: Preliminary condenser specific efficiency results ............................................................... 32 Figure 15: State-wide energy analysis summary for condenser specific efficiency measure............... 32 Figure 16: Analysis results for prototypes, system configurations, and condenser types with benefit/cost ratios less than 1 ......................................................................................................... 33 Figure 17: Suction group design SST and Base Case SST setpoints.................................................... 35 Figure 18: Statewide savings results for floating suction pressure ....................................................... 35 Figure 19: Statewide savings results for mechanical subcooling measure ........................................... 37 Figure 20: Suction line heat gain assumptions (MT systems) .............................................................. 38 Figure 21: Suction line heat gain assumptions (LT systems) ............................................................... 38 Figure 22: LSHX sizing assumptions for cost and performance .......................................................... 38 Figure 23: State-wide savings analysis for liquid-suction heat exchangers (MT Walk-Ins) ................ 39 Figure 24: State-wide savings analysis for liquid-suction heat exchangers (LT Walk-Ins) ................. 40 Figure 25: State-wide savings analysis for liquid-suction heat exchangers (MT display cases) .......... 40 Figure 26: State-wide savings analysis for liquid-suction heat exchangers (LT display cases) ........... 41 Figure 27: MT walk-in LSHX simulations with BCR
