Energy Department Releases Updated Versions of Open-Source Building Energy Modeling Tools EnergyPlus and OpenStudio

Feb. 26, 2021

Last fall, the U.S. Department of Energy and its National Laboratories released updated versions of their open-source, whole-building energy modeling tools, the EnergyPlus™ engine, and the OpenStudio™ Software Development Kit (SDK).

EnergyPlus 9.4.0 continues to emphasize object-oriented refactoring and defect resolution. The current version includes a refactored autosizing library and fixes for 120 known issues and bugs. EnergyPlus 9.4.0 also incorporates several performance enhancements from the EnergyPlus 10X project, including the ability to directly generate native CSV (comma separated variable) output and to control the generation of various output files, and a new PerformancePrecisionTradeoffs object that allows users to explicitly control simulation speed by sacrificing some precision.

EnergyPlus 9.4.0 also includes a number of new features. Multiple enhancements have been made to Low Temperature Radiant Systems, including support for multi-zone systems, improved control capabilities, and enhancements to setpoint definitions for these systems. New reports have been added for equipment, envelope as well as for emerging resilience metrics. Support for multiple scheduled shading devices per window has been added. Finally, the recently added Python Plugin feature has been enhanced with updated examples, API extensions, and new calling points, functions, and variables. A full list of new features and bug fixes is available on the release notes page. Feature suggestion, discussion, voting, and tracking and issue reporting and tracking are available on the issues page.

OpenStudio 3.1.0 includes updates to the OpenStudio Application Programming Interface (API), Command Line Interface (CLI), Server, and Standards gem. As originally announced in 2018, the Energy Department is no longer sponsoring, managing, or distributing the graphical OpenStudio Application. OpenStudio 3.1.0 supports EnergyPlus 9.4.0 as well as the latest version of the Radiance lighting engine. This release includes new cooling coil objects, improved support for schedules, shading devices, and refrigeration systems, and cross-platform support for C#/.NET bindings. It also address 40 outstanding issues and bugs. The updated Standards gem includes a number of updates as well as new prototoypes for tall and super-tall buildings. As with EnergyPlus, a full list of new features and bug fixes is available on the release notes page, and feature and bug tracking are available on the issues page.

Installation package downloads for Windows, Mac OS X, and Ubuntu Linux are available at and, respectively. Peer-to-peer and developer support is available via the forum. More information about all of DOE’s building energy modeling software and research projects can be found at Stay safe everyone!


U.S. Department of Energy Office of Energy Efficiency and Renewable Energy

Building Technologies Office


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