The document discusses adding refrigeration modeling capabilities to OpenStudio, an interface for EnergyPlus that allows graphical input. Refrigeration systems and components like display cases, walk-ins, condensers, compressors have been added. The implementation occurred over 4 phases, starting with basic components and expanding to include more complex systems and component metadata. The OpenStudio interface simplifies and encourages energy modeling of buildings with refrigeration loads.

1. Refrigeration Modeling
Components in
OpenStudio
Mark Adams
Jibonananda Sanyal
Brian Fricke
Kyle Benne
Oak Ridge National Laboratory
National Renewable Energy Laboratory

2. 2
Outline
• Building Energy Modeling
• Refrigeration in EnergyPlus
– Systems/components
• OpenStudio
– Adding refrigeration capabilities
– Implementation
– GUI
• Conclusion

3. 3
Building Energy Modeling
• Whole building energy modeling tools are capable of:
– Simulating annual energy use
• Electricity, gas, water
• Hourly or sub-hourly output
– Modeling building envelope, heating and cooling loads and HVAC
performance based on detailed weather data and building
construction data, variations in ambient
– Determine interaction effects of the equipment with their
environment
• EnergyPlus
– Developed for the U.S. Department of Energy
– Available for free: www.energyplus.gov

4. 4
Refrigeration Modeling in EnergyPlus
• Refrigeration System Types
– Multiplex DX Systems
– Cascade Systems
– Secondary Loops
– Transcritical CO2 Booster Systems
• Components
– Compressors
– Condensers (air-cooled, evap-cooled, water-cooled)
– Gas coolers (air-cooled)
– Mechanical subcoolers
• Loads
– Display Cases
– Walk-Ins
– Air Chillers (unit coolers)
• Component performance specified with performance maps and detailed
manufacturer-supplied performance data

5. 5
Refrigeration Systems
Multiplex DX
Secondary Loop/
Cascade
Transcritical CO2
Booster

6. 6
EnergyPlus Input/Output
• EnergyPlus input and output is
text-based
– Not “user-friendly”
– Time-consuming and
cumbersome
– Graphical interface required for
“friendly” user input
• OpenStudio
– Graphical interface for
EnergyPlus
– Recently added refrigeration
capabilities to OpenStudio
– www.openstudio.nrel.gov

7. 7
OpenStudio
• Collection of software tools to support whole building energy
modeling using EnergyPlus
– Graphical interfaces
– Software development kit (SDK)
• OpenStudio Application
– Graphical editing of schedules, loads, constructions, materials
– Drag-and-drop interface for spaces, zones, HVAC components
• Tools
– Sketch-up plug-in
– Parametric Analysis
– Run Manager
– Results Viewer

8. 8
Refrigeration Modeling in OpenStudio
• Models are included for the following refrigeration systems
and components
– System types: centralized DX, cascade, secondary loop,
transcritical CO2 booster
– Refrigerated display cases
– Walk-in coolers and freezers
– Air cooling coils
– Air-cooled, evaporatively-cooled, or water-cooled condensers
– Air-cooled gas coolers
– Compressors
– Mechanical subcoolers and liquid-suction line heat exchangers
• Tabular thermodynamic data for refrigerants can be supplied

9. 9
Implementation
• Agile software development
• 4 Phases
– Initial phase: six main components
• Refrigeration System, Compressor, Display Case, Walk-In, Air-Cooled Condenser and
Secondary System.
– Second phase: 5 components
• Mechanical Subcooler, Liquid-Suction Subcooler, Cascade Condenser, Evaporative-
Cooled Condenser, and Water-Cooled Condenser.
– Third phase
• Air Chillers, Transcritical Refrigeration System, Transcritical Compressors, Air-Cooled
Gas Cooler, and waste heat recovery using the Air Heating Desuperheater Coil or the
Water Heating Desuperheater Coil.
• Metadata from the hundreds of refrigerated display cases and refrigeration
compressors added to the Buildings Components Library (BCL)
– Fourth phase
• Documentation of the API

10. 10
OpenStudio user interface showing blank refrigeration system template

11. 11
A refrigeration system complete with components

12. 12
Grid view showing details of the attached display cases and walk-ins

13. 13
Configuring multiple racks of a refrigeration system

14. 14
Conclusions
• Refrigeration modeling capabilities exist in EnergyPlus
– Text-based input required
– Time-consuming and cumbersome for users
• Refrigeration capabilities added to OpenStudio
– Graphical interface for building refrigeration systems
– Simplifies process of inputting refrigeration system parameters
– Encourage use of whole building energy simulation for buildings
with refrigeration systems (supermarkets, warehouses, etc.)

15. 15
Thank you!
Any Questions?