Openstudio 2.9.1 May 2026

OpenStudio 2.9.1 is a specific version of the open-source software development kit (SDK) and collection of tools used for building energy modeling (BEM). It acts as a comprehensive platform that simplifies the use of the EnergyPlus simulation engine for whole-building energy analysis and Radiance for advanced daylighting studies. Core Role in Energy Modeling

model.getObjectsByType("OS:Construction".to_IddObjectType).size → Counts constructions.
model.getThermalZones.each puts z.name → Lists all zones.
model.getSpaces.each s → Batch edits heights.

offer more features, 2.9.1 remains a nostalgic milestone for many modelers—a reminder of the time they first learned to "speak" the language of building energy. technical release notes for version 2.9.1 or see how it compares to modern versions openstudio 2.9.1

The 2.9.1 ecosystem featured a very distinct suite of tools that defined how energy modelers operated at the time: 1. The OpenStudio Application (Desktop GUI) OpenStudio 2

Run the installer as administrator (Windows) or drag to Applications (macOS).

Install SketchUp Extension:

3.2. HVAC & Sizing

Fixed bug where the Sizing:Plant object would not correctly update loop exit temperature setpoints when using the Python API.
Resolved error where autosizing of AirLoopHVAC:UnitarySystem with multispeed fans could produce incorrect airflow values.
Corrected translation of Coil:Heating:Water to EnergyPlus IDF format when the coil is used in a dedicated outdoor air system (DOAS).