OpenStudio-ERI v1.12.0

OpenStudio-ERI version 1.12.0 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.12.0 uses OpenStudio v3.11.0, EnergyPlus v25.2.0, and HPXML v5.0-rc1. Please visit the OpenStudio-ERI v1.12.0 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Updates to OpenStudio-HPXML 1.12/OpenStudio 3.11/EnergyPlus 25.2.
• Updates to HPXML v5.0-rc1.
  • Breaking change: HPXML namespace changed from http://hpxmlonline.com/2023/09 to http://hpxmlonline.com/2025/12.
• Updated DX heat pump and air conditioner models per HERS Addendum 103.
  • Compressor lockout temperatures for Rated Home defaults and Reference Home updated from 0F (single/two stage) and -20F (variable speed) to 5F and -10F, respectively.
  • Dual-fuel heat pumps now have the HP sized using the greater of the heating design temperature and 25F.
  • Pan heaters no longer operate when the outdoor temperature is below the compressor lockout temperature.
• Adds a warning if there are more than 300 unmet hours for heating or cooling; setpoint tolerance increased from 0.36 deg-F (0.2 deg-C) to 0.5 deg-F.
• Runtime speed improvements for homes with multiple ground source heat pumps.
• Utility bill scenarios can now be defined for the Rated/Reference Homes; see the documentation for more information.
• The Battery/NominalCapacity input is no longer used.
• Output updates:
  • Breaking change: Annual peak load outputs for heating and cooling now use units of Btu/h instead of kBtu/h for consistency with other outputs.
• Updates schematron validation error messages to be more user friendly.

Bugfixes

• Fixes incorrect hot water (gallons) output for solar thermal systems using SolarFraction.
• Fixes possible "Failed to process String" EnergyPlus error when requesting component loads.

OpenStudio-ERI v1.11.2

OpenStudio-ERI version 1.11.2 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.11.2 uses OpenStudio v3.10.0 (w/ HP bugfix), EnergyPlus v25.1.0, and HPXML v4.2. Please visit the OpenStudio-ERI v1.11.2 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

Bugfixes

• Fixes heat pump heating performance sensitivity to indoor temperatures.

OpenStudio-ERI v1.11.1

OpenStudio-ERI version 1.11.1 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.11.1 uses OpenStudio v3.10.0, EnergyPlus v25.1.0, and HPXML v4.2. Please visit the OpenStudio-ERI v1.11.1 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Breaking change: Clothes dryers now require Vented (true or false) to be provided per ANSI/RESNET/ICC Standard 301-2022 Addendum C.

OpenStudio-ERI v1.11.0

OpenStudio-ERI version 1.11.0 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.11.0 uses OpenStudio v3.10.0, EnergyPlus v25.1.0, and HPXML v4.2. Please visit the OpenStudio-ERI v1.11.0 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Updates to HPXML v4.2.
• Updates shared pump power for ground-source heat pumps on a shared recirculation loop to cycle with heating/cooling load rather than operate continuously per RESNET HERS Addendum 94.
• Adds RESNET HERS Addendum 77 to adjust HPWH performance when installed in confined space, used when ERI version is "latest".
  • Breaking change: A new extension/HPWHInConfinedSpaceWithoutMitigation input is now required for HPWHs; when true, extension/HPWHContainmentVolume is also required.
• Updates to DOE Efficient New Homes program (formerly Zero Energy Ready Homes)
  • Updates Single Family Version 2 to Rev 3 and Multifamily Version 2 to Rev 2.
  • Breaking change: Replaces all references to "ZERH" with "DENH" (e.g., renames ZERHCalculation to DENHCalculation and renames various output products).
• Updated DX heat pump and air conditioner models per latest draft of RESNET HERS Addendum 82.
• Allows multiple PV inverters with different efficiencies and uses a weighted-average efficiency in the model (previously threw an error).
• Improves electric water heater tank losses when using EnergyFactor as the metric; now consistent with how UniformEnergyFactor is handled.

Bugfixes

• Fixes an EMS bug in heat pump defrost models that over-estimates defrost fractions.
• Fixes possibility of "Sum of energy consumptions ... do not match total" error when there are multiple HVAC/DHW systems whose load fractions don't sum to 1.

OpenStudio-ERI v1.10.0

OpenStudio-ERI version 1.10.0 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.10.0 uses OpenStudio v3.10.0, EnergyPlus v25.1.0, and HPXML v4.2-rc2. Please visit the OpenStudio-ERI v1.10.0 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Updates to OpenStudio 3.10/EnergyPlus 25.1/HPXML v4.2-rc2.
• Breaking change: ERI version of "latest" now includes RESNET HERS addenda not yet incorporated in ANSI 301.
  • Adds RESNET HERS Addenda 81 and 90f for "latest" (updates calculations for dishwashers, clothes washers, fixtures, and hot water waste).
• Updated DX heat pump and air conditioner models per RESNET HERS Addendum 82.
  • Breaking change: CompressorType required for central and mini-split air conditioners and heat pumps.
  • Breaking change: HeatingCapacity17F required for central and mini-split heat pumps; deprecates HeatingCapacityRetention.
  • Breaking change: EER2 or EER inputs (AnnualCoolingEfficiency[Units="EER2" or Units="EER"]/Value) required for central and mini-split air conditioners and heat pumps.
  • Breaking change: BackupHeatingLockoutTemperature and BackupHeatingSwitchoverTemperature inputs are no longer allowed.
  • Breaking change: CompressorLockoutTemperature is no longer allowed for HPs w/ fossil fuel backup; it is only allowed for HPs with electric backup or no backup.
  • Breaking change: SHR inputs (e.g., CoolingSensibleHeatFraction) are no longer allowed.
  • Allows optional design airflow rate inputs (extension/HeatingDesignAirflowCFM and extension/CoolingDesignAirflowCFM) to be used when the blower fan airflow is measured.
  • Allows optional extension/FanMotorType input for central equipment.
  • Allows optional extension/EquipmentType inputs for central air conditioners and heat pumps; only used for SEER/SEER2, EER/EER2, and HSPF/HSPF2 conversions.
• Allows multiple versions of a given program (e.g., ENERGY STAR 3.2 and 3.3) to be calculated in a single call.
  • Breaking change: Output directories and files have been reorganized/renamed (output file contents are not changed in any way).
• Allows specifying the number of parallel processors to use for simulations with -n <NUM> or --num-proc <NUM>.
• Infiltration improvements:
  • Improves defaulting for InfiltrationHeight.
  • Allows optional WithinInfiltrationVolume input for conditioned basements; defaults to true.
  • AverageCeilingHeight is no longer used (for infiltration calculations, Hf = InfiltrationVolume/CFA).
• Output updates:
  • Adds new outputs for net peak electricity (summer/winter/annual); same as total peak electricity outputs but subtracts power produced by PV.
  • Adds generator electricity produced to total fuel/energy use; previously it was only included in net values.

Bugfixes

• Fixes 301validator schematron file extension (.sch, not .xml).
• Fixes U-factor for floors over 'other multifamily buffer space' per ENERGY STAR MFNC Rev 05.
• Fixes modeling of 0.3 ACHnatural infiltration minimum for MF dwelling units where Aext < 0.5 and the mechanical ventilation system is solely exhaust-only.
• Fixes ZERH Target Home and ESRD so that dual-fuel heat pumps are preserved.
• Fixes battery charging/discharging not being included in peak electricity outputs.
• Fixes error if there's a vented attic with zero roof pitch.

OpenStudio-ERI v1.9.4

OpenStudio-ERI version 1.9.4 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.9.4 uses OpenStudio v3.9.0, EnergyPlus v24.2.0, and HPXML v4.1-rc1. Please visit the OpenStudio-ERI v1.9.4 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Adds ENERGY STAR ERI calculation for SFNH National v3.3 and MFNC National v1.3.
• Updates to ENERGY STAR SFNH Rev 14 and MFNC Rev 05.
  • Breaking change: Building types "single-family detached" and "single-family attached" may only be used for SFNC versions and "apartment unit" may only be used for MFNC versions.
  • ENERGY STAR MFNC National 1.2 now uses 100% LED lighting.
• WeatherStation/extension/EPWFilePath is now optional; if not provided, the closest TMY3 weather station will be automatically selected based on the zip code.
• Improves eGrid/Cambium region lookup by zipcode when an exact match is not found.

Bugfixes

• Fixes ZERH Target Home and ESRD so that operable window fraction (for natural ventilation) from the Rated Home is preserved.
• Fixes possible error if there's a surface w/ interior unconditioned space and exterior "other housing unit".

OpenStudio-ERI v1.9.3

OpenStudio-ERI version 1.9.3 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.9.3 uses OpenStudio v3.9.0, EnergyPlus v24.2.0, and HPXML v4.1-rc1. Please visit the OpenStudio-ERI v1.9.3 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

Bugfixes

• Fixes possibility of ERI Rated Home having extra balanced supplemental ventilation due to floating point comparison.

OpenStudio-ERI v1.9.2

OpenStudio-ERI version 1.9.2 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.9.2 uses OpenStudio v3.9.0, EnergyPlus v24.2.0, and HPXML v4.1-rc1. Please visit the OpenStudio-ERI v1.9.2 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Updates HERS test outputs to match the latest RESNET accreditation forms.

OpenStudio-ERI v1.9.1

OpenStudio-ERI version 1.9.1 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.9.1 uses OpenStudio v3.9.0, EnergyPlus v24.2.0, and HPXML v4.1-rc1. Please visit the OpenStudio-ERI v1.9.1 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

Bugfixes

• Fixes clothes washer configurations for ZERH v2 and ENERGY STAR SFNH 3.2/MFNC 1.2 programs when the rated home does not include a clothes washer.

OpenStudio-ERI v1.9.0

OpenStudio-ERI version 1.9.0 has been released. The OpenStudio-ERI workflow calculates an Energy Rating Index (ERI) using the Department of Energy's OpenStudio/EnergyPlus building simulation platform. The open-source workflow is intended to be used by residential software tools that provide a HPXML building description file.

OpenStudio-ERI v1.9.0 uses OpenStudio v3.9.0, EnergyPlus v24.2.0, and HPXML v4.1-rc1. Please visit the OpenStudio-ERI v1.9.0 documentation for instructions on how to get started, how to connect software tools to the workflow, etc. The full set of US TMY3 weather files can be obtained from here.

New Features

• Updates to OpenStudio 3.9/EnergyPlus 24.2/HPXML v4.1-rc1.
• Adds 2024 IECC ERI pathway calculation.
• Breaking change: Renamed Emissions: <EmissionsType>: RESNET: XXX to Emissions: <EmissionsType>: ANSI301: XXX in Annual Home CSV output files.
• Implements ANSI/RESNET/ICC Standard 301-2022 Addendum E for CFIS systems.
  • ERICalculation/Version and CO2IndexCalculation/Version can now be "2022CE".
  • Breaking change: Removes FanPower/FanPowerDefaulted and VentilationOnlyModeAirflowFraction inputs for CFIS systems.
  • Breaking change: Adds CFISControls/HasOutdoorAirControl and CFISControls/extension/ControlType inputs for CFIS systems.
  • Adds choice of "none" for CFISControls/AdditionalRuntimeOperatingMode input for CFIS systems.
  • Adds optional CFISControls/extension/SupplementalFanRunsWithAirHandlerFan input for CFIS systems.
• Adds inputs for modeling skylight curbs and/or shafts.
• Relaxes IECC climate zone requirements.
  • IECC climate zone years other than 2006 are now always optional; for programs that use specific IECC climate zone years (e.g., 2021 for ZERH SF 2.0), that year is used if provided, otherwise the next earliest provided year will be used with the assumption that the climate zone has not changed across the years.
  • See the documentation for more information.
• Updates HERS Diagnostic Output to v0.3.0.

Bugfixes

• Adds error-checking for NumberofConditionedFloorsAboveGrade=0, which is not allowed per the documentation.
• Fixes error if a heating system and a heat pump (that only provides cooling) are attached to the same distribution system.
• Fixes double counting of battery storage losses in ERI calculation; CO2e Index is unaffected.
• Misc Manual J design load calculation improvements.
• Fixes GSHP rated fan/pump powers in net to gross calculations.