OpenStudio
OpenStudio is an open-source building energy modeling platform that wraps EnergyPlus and Radiance with a graphical application, SDK, and Ruby or Python Measures for whole-building simulation workflows.
Whole-building energy models still depend on EnergyPlus under the hood, but raw IDF editing scares off many design teams. OpenStudio adds a stable SDK, graphical editors, and scripting hooks so researchers and practitioners can build envelopes, loads, schedules, and HVAC without hand-editing every object (OpenStudio homepage, 2026).
The stack spans several entry points. The OpenStudio Application gives a desktop UI for space types, thermal zones, and measures, while the SDK and CLI expose Ruby, Python, and C# bindings for automation. Optional tools include a SketchUp plug-in for geometry, FloorspaceJS for envelope layout, the Parametric Analysis Tool for design alternatives, and ResultsViewer for time-series plots (OpenStudio homepage and Coalition docs, 2026).
Measures are the extensibility layer: reusable Ruby or Python scripts posted on the Building Component Library automate transformations from simple lighting power tweaks to ASHRAE 90.1 Appendix G compliance workflows. OpenStudio Standards ships prototype building templates and code-compliance measure sets used in utility and LEED studies (OpenStudio homepage, 2026).
Everything is free to download. The OpenStudio SDK 3.11.0 release bundles EnergyPlus 25.2.0 and ships installers for Windows, macOS, and Linux, while the OpenStudio Coalition maintains the graphical application installers for the same platforms (NREL GitHub release notes and Coalition docs, 2026).
Specifications
Pricing
Platforms
Used for
Used by
Tasks
Pros and cons
Pros
- Free open-source stack with no license fees
- Cross-platform support on Windows, macOS, and Linux
- Large library of shared Measures on the Building Component Library
- Bundles current EnergyPlus and Radiance releases with the application installer
- Multiple entry points from GUI to Ruby, Python, and CLI automation
Cons
- Steep learning curve compared to commercial energy modelers
- Parametric Analysis Tool is not available on Linux
- SketchUp plug-in requires SketchUp Pro or Studio, not the free web version
- Measure compatibility can break across major SDK version upgrades
- Graphical application installers now require an OpenStudio Coalition account for some releases
Key features
EnergyPlus integration: OpenStudio SDK exposes a version-controlled API to the EnergyPlus simulation engine for whole-building energy analysis.
OpenStudio Application: Desktop GUI for editing envelopes, space types, thermal zones, schedules, loads, and HVAC on .osm models.
Measures scripting: Ruby and phase-1 Python Measures automate model edits, reporting, and compliance transformations via the Building Component Library.
Geometry workflows: Built-in FloorspaceJS editor, optional SketchUp plug-in, and import support for gbXML and IFC geometry.
Radiance daylighting: Bundled Radiance support enables advanced daylight analysis alongside energy simulation.
Parametric Analysis Tool: Study multiple design alternatives by applying measure combinations to a seed model (Windows and macOS).
OpenStudio Standards: Prototype building libraries and ASHRAE 90.1 Appendix G measure sets for code and certification studies.
Cross-platform SDK: CLI and language bindings for Ruby, Python, and C# run on Windows, macOS, and Linux.
Pricing
Open source (all components)
per year
Free
SDK, Application, Measures, and CLI are free. Confirm download options on openstudio.net.
Frequently asked questions
Is OpenStudio free to use?
Yes. OpenStudio is an open-source project led by U.S. national laboratories, and the OpenStudio Coalition states the OpenStudio Application is free to use (OpenStudio homepage and Coalition GitHub, 2026). There is no paid license; you download installers from openstudio.net, GitHub, or the Coalition member portal.
Does OpenStudio run on Mac and Linux?
The OpenStudio SDK ships Windows, macOS (Intel and ARM), and Linux installers, including Ubuntu 22.04 and 24.04 packages in the 3.11.0 release (NREL GitHub, 2026). The OpenStudio Application supports 64-bit Windows, macOS, and Ubuntu per Coalition installation docs.
What file formats does OpenStudio support?
OpenStudio models use the native .osm format and export to EnergyPlus .idf files for simulation. The platform also supports gbXML and IFC import for geometry creation according to the project homepage (OpenStudio.net, 2026).
Can OpenStudio run ASHRAE 90.1 Appendix G compliance studies?
Yes. OpenStudio Standards provides Measures and prototype resources that automate Appendix G performance rating method transformations, a workflow commonly used for code compliance, LEED certification, and utility incentive calculations (OpenStudio homepage, 2026).
OpenStudio vs DesignBuilder: which is better for EnergyPlus modeling?
Both target EnergyPlus simulation, but OpenStudio is free, scriptable with Measures, and maintained as an open-source research platform with SDK bindings. DesignBuilder is a commercial GUI-focused modeler with integrated CFD and costing modules. Teams that need transparent, taxpayer-funded program workflows often favor OpenStudio's open Measures and BCL sharing model (OpenStudio homepage, 2026).
Which EnergyPlus version ships with OpenStudio 3.11.0?
The OpenStudio SDK 3.11.0 release updates to EnergyPlus v25.2.0 according to the official GitHub release notes published January 15, 2026. Each OpenStudio Application release bundles the latest compatible EnergyPlus build in its installer.
Who maintains OpenStudio?
OpenStudio is developed in collaboration by U.S. Department of Energy national laboratories including NLR, ANL, LBNL, ORNL, and PNNL (OpenStudio Coalition docs, 2026). The OpenStudio Coalition maintains the graphical OpenStudio Application and SketchUp plug-in for the community.