CBECC-Com: California Building Energy Code Compliance (for COMmercial/Nonresidential buildings) software

CBECC-Com (California Building Energy Code Compliance) is an open source project that may be used by Code Agencies, Rating Authorities, or Utility Programs in the development of energy codes, standards, or efficiency programs. Architects, engineers, and energy consultants may also use these tools to demonstrate compliance with energy codes or beyond-code programs.

The software's key components are:

  • Graphical User Interface (GUI) - allows users to enter details about a proposed building's design
  • Ruleset - a computer-processable form of the building energy code
  • Compliance Manager - the core of CBECC. Uses the ruleset to assess whether the building complies with the energy code.
  • Connection to the U.S. Department of Energy's EnergyPlus Simulation Engine - performs energy simulations to compare proposed building energy consumption to the energy code "budget"
  • Report Generator - generates forms and other reports to summarize the building's compliance characteristics. Forms may be submitted for building permits, or as documentation for other programs.
  • Application Programmng Interface (API) Documentation - The purpose of this document is to provide information needed to develop software interfaces to the CEC Compliance engine DLL(s).

CBECC-Com Version includes the Ruleset for California's 2013 Title 24 Energy Code. The Title 24 Ruleset represents the performance approach for compliance as described in the 2013 Nonresidential Alternative Calculation Method (NACM) Reference Manual. It also features an API to allow third party software developers to utilize the functionality of the CBECC-Com Compliance Manager.

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CBECC-Com Features

CBECC-COM 2013 is an open-source software program developed by the California Energy Commission for use in complying with the 2013 update to the Non-Residential Building Energy Efficiency Standards. The software is capable of generating the standard design model as per the Alternate Compliance Method for a given user model and perform the annual energy analysis comparing its energy efficiency relative to the 2013 Standards. CBECC-Com’s scope, features, and capabilities are listed below.

Scope
  1. Newly constructed buildings
  2. Addition/Alterations and Partial Compliance
  3. CBECC-Com will produce results of the performance tests described in the 2013 Nonresidential ACM Reference Manual. Documentation is available on the Reference Method page.
  4. The 2013 Standards ruleset and rules processing software will have the capability to be included in third party compliance software using Dynamic Linked Libraries (DLLs) and will include ruleset encryption to "lock" the 2013 Standards ruleset.
Site/Building
  1. Include identifying information
  2. Include other general information required for compliance forms
  3. Include location information
  4. Identify climate zone and weather/design day files from the project site ZIP code
Envelope
  1. Provide a comprehensive list of accurately described opaque materials
  2. Combine materials into constructions
  3. Describe fenestration performance properties via the simplified approach (U-value, Solar Heat Gain Coefficient-SHGC, Visible Transmittance-VT)
  4. Provide constructions which meet the u-factor requirements by climate zone of opaque surfaces
  5. Provide glazing units which meet climate zone requirements for skylights and vertical glazing
  6. Apply exterior insulated constructions to demising surfaces
  7. Check that proposed exterior constructions meet mandatory u-value requirements
  8. Remove user model building shades
  9. Retain user model geometry
  10. Adjust excess user model fenestration to standard design maximum WWR and SRR values
Lighting and Other Internal Loads
  1. Replace user lighting systems with simple Lighting Power Density (LPD) values based on space function
  2. Allow simple lighting inputs for LPD and lighting schedules without the need to specify details of an interior lighting system
  3. Allow detailed lighting inputs for credits and allowances:
    1. Lighting Controls and associated power adjustment factors (PAF)
    2. Area Category Lighting Allowances
    3. Tailored Lighting Allowances
  4. Replace user occupancy and equipment loads with Alternative Calculation Method (ACM) specified values
  5. Replace user specified infiltration rates with ACM values
  6. Replace user specified schedules with ACM schedules
  7. Combine space level data into zones
  8. Lighting heat gain factors adjusted for plenum returns
  9. Lighting heat gain factors adjusted for plenum return vs. non-plenum return configurations
  10. Daylighting control minimum dimming light and power fractions prescribed as a function of luminaire type (not user input)
  11. Daylighting controls are no longer specified by default where they are mandatory. A project level flag enables this functionality, however projects for which daylighting controls have been installed by default cannot be used for compliance
  12. Space functions and special rules enabled for process spaces: computer rooms, commercial kitchens and laboratories
HVAC
  1. Replace user specified HVAC system with baseline system
    1. Except data center, laboratory, kitchens
    2. Baseline sizing run is autosized
    3. Baseline run hard sized using baseline sizing results
  2. Model user specified HVAC systems with user-supplied sizing:
    1. Package Single Zone (PSZ)
    2. Single Zone Variable Air Volume (SZVAV)
    3. Package Variable Air Volume (PVAV)
    4. Variable air volume (VAV)
    5. Package Terminal Air Conditioner (PTAC)
    6. Package Terminal Heat Pump (PTHP)
    7. Water Source Heat Pump (WSHP)
    8. Water-source condensers as an option with new ‘WSHP’ zone system, as well as related dual setpoint control of condenser water loop supply temperature
    9. Four Pipe Fan-Coil units (FPFC)
    10. Baseboard Heating
    11. Indirect, Direct and Indirect-Direct Evaporative Cooling for use with Air Systems
    12. Exhaust Systems
    13. Dedicated outdoor air systems (DOAS) for use with zone systems in nonresidential applications
    14. Plenum Supply and Return air flow paths for Air Systems
    15. Series Fan-powered VAV Boxes
    16. VAV boxes without reheat coils
    17. CRAC and CRAH systems for computer rooms
    18. Special requirements enabled for process spaces (computer rooms, kitchens, laboratories)
    19. Heating coils
      1. Gas furnace
      2. Hot water
      3. Electric
      4. Direct Expancsion (DX)(heat pump)
    20. Cooling Coils
      1. Chilled water
      2. Direct Expansion(DX)
    21. Boilers
      1. Hot water
      2. Gas
      3. Oil
      4. Electric
      5. Natural draft
      6. Mechanical draft
    22. Chillers
      1. Screw
      2. Reciprocating
      3. Centrifugal
      4. Air-cooled
      5. Water-cooled
    23. Chilled water loop pumping
      1. Primary only
      2. Primary-secondary
    24. Economizers (air side)
      1. Non-integrated
      2. Integrated
    25. Economizer Controls
      1. Fixed temperature
      2. Differential temperature
      3. Fixed enthalpy
      4. Differential enthalpy
Domestic Water Heating
  1. Storage water heaters
    1. Gas
    2. Electric
    3. Oil

    For all nonres building occupancies other than High-Rise Multi-family and Hotel/Motel, there are NO prescriptive service water heating requirements. This means that there are only mandatory service water heating requirements for most nonresidential buildings, and mandatory requirements cannot be traded off in the performance compliance approach.

  2. Instantaneous water heaters
  3. Recirculating domestic hot water (DHW) systems for residential occupancies
  4. Solar fraction input added to service hot water systems and recirculating DHW systems
Output
  1. Report simulation errors and warnings including useful descriptions
  2. Report number of hours with setpoint not met by thermal zone (UMLH - Unmet Load Hours)
  3. Report energy consumption by fuel and end-use
  4. Report TDV energy by end use
  5. Report TDV energy comparison of Proposed and Standard Design, including Compliance Margin
  6. Generate "NRCC-PRF-01-E" summary compliance form
  7. Generate Standard Design report for any Proposed Design
  8. Options to store hourly simulation results and TDV multipliers to CSV file for each analysis model
Interface
  1. Ability to access and modify parameters needed to simulate the above
  2. Option to perform simulations in two modes:
    1. Proposed Only (applies rules and simulates the Proposed Design)
    2. Proposed and Standard (applies rules and simulates the Proposed and Standard Designs)
  3. CBECC-Com QuickStart Guide available from "Help" tab
  4. CBECC-Com User's Manual available from "Help" tab
  5. CBECC-Com software license available from "Help" tab
  6. Tools menu bar options to view project folder and most recent compliance report
  7. Tools menu bar options to view/edit or delete the project log file and to edit INI file entries
  8. Reorganization of space/thermal zone screen dialogs and addition of tree description information for select HVAC components
  9. Ability to change building component parent/child order via new options on the right-mouse button menus in the UI’s component tree
  10. "Mouse Over" pop-up descriptions/help for many building model parameters
  11. Ability to view and edit polyloop coordinates for detailed geometry models
  12. Network drive paths allowed for data and project files (though simultaneous execution using shared network drives not yet supported)
Documentation
  1. Nonresidential ACM Reference Manual
  2. Meeting criteria in 2013 Nonresidential ACM Approval Manual (e.g. CBECC-Com Users Manual)
  3. Issues Log available with each CBECC-Com version release to document bugs identified and fixed