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DOE Technology Manager: Amir Roth
Project Manager: Luigi Gentile Polese, NREL


  • National Renewable Energy Lab (NREL) – Golden, CO
  • Argonne National Lab (ANL) – Argonne, IL
  • Lawrence Berkeley National Lab (LBNL) – Berkeley, CA
  • Oak Ridge National Lab (ORNL) – Oak Ridge, TN
  • Pacific Northwest National Lab (PNNL) – Richland, WA
  • GARD Analytics – Oak Park, IL
  • Empty Crate Software – Denver, CO


  • simuwatt Inc. – Boulder, CO
  • Performance Systems Development – Ithaca, NY
  • Big Ladder Software – Denver, CO
  • Xcel Energy – Denver, CO
  • National Grid – New York, NY
  • Austin Energy – Austin, TX
  • Energy Trust of Oregon – Portland, OR
  • Los Angeles Department of Water and Power – Los Angeles, CA
  • California Energy Commission – Sacramento, CA
  • NORESCO – San Francisco, CA
  • Bonneville Power Administration – Portland, OR
  • New York State Energy Research and Development Authority – Albany, NY
  • The Energy Coalition – Los Angeles, CA
  • Penn State University – State College, PA
  • Wrightsoft – Lexington, MA
  • Carmelsoft – San Rafael, CA
  • Group14 Engineering – Denver, CO
  • Ambient Energy – Denver, CO
  • Natural Resources Canada – Ottawa, ON, Canada
  • Department of Defense ESTCP – Washington, DC
  • National Institute of Standards and Technology – Gaithersburg, MD
  • California Technical Forum – San Francisco, CA

DOE Funding: $1,560,000 in FY17; $9,360,000 to date
Cost Share: $7,011,000 to date
Project Term: 2010 –
Funding Opportunity: Commercial Buildings Integration core funding
Related projects: EnergyPlus, Spawn of EnergyPlus, Radiance, Asset Score, BayREN, CBERD, Scout, BEOPT, BuildingSync, OpenEfficiency

Project Objective

OpenStudio is DOE’s open-source software development kit (SDK) for building energy modeling (BEM). OpenStudio is a developer’s platform aimed at dramatically reducing the effort required to build and maintain applications that use BEM and is aimed at growing and supporting the ecosystem of end-user BEM tools and services. The OpenStudio project includes a number of example applications—a plug-in for the SketchUp 3D drawing program, a graphical model editing application, a results viewer, and a parametric analysis tool—that demonstrate the capabilities of the SDK and integration practices and which are usable in their own right.

OpenStudio allows third parties to focus on adding individual differentiating value and on serving their clients by providing common core infrastructure. BEM engines like EnergyPlus interact with applications via large, static, and sometimes cumbersome files. OpenStudio facilitates application development by presenting EnergyPlus inputs and outputs as a dynamic, object oriented data model with application programming interface (API), a much easier construct for applications to deal with. In addition to low-level model and result access, OpenStudio also provides common high-level abstractions like space types and spaces and functionality like instantiation and configuration of standard HVAC systems, and data import from standard schemas like gbXML. Finally, in addition to EnergyPlus, OpenStudio also exports inputs for and import results from other engines like the Radiance lighting engine and the CONTAM airflow engine, supporting multiple analyses from a single model.

A distinctive feature of OpenStudio is the concept of Measures, small interpreted programs that can transform a model, or query a model and its simulation results. Measures—named so because many of them correspond to energy-conservation measures (ECMs)—can perform transformations that are as simple as changing insulation levels or as complex as reconfiguring fenestration, shading, and controls to optimize for daylight harvesting. Measures are lightweight, easy to create and modify, and provide a way to customize OpenStudio and its capabilities without having to modify the core SDK. Beyond enabling parametric analysis—the systematic application of measures to a model in various combinations—measures dramatically reduce the effort required to construct energy models, while improving their consistency and quality. Over 200 Measures are already available on the Building Component Library (BCL), an online repository of OpenStudio content. Many more are currently in development. One recently developed and especially powerful measure is “Create Performance Rating Method Baseline Building Model” which automates the ASHRAE 90.1 “Appendix G” baselining procedure that is at the heart of both code-compliance and above code BEM applications LEED and energy-efficiency incentive documentation. Automating this procedure eliminates tedious modeler effort and frees up time and budget for more creative and productive activities like evaluating energy-efficiency strategies.

One focus of the OpenStudio project is support for large-scale analysis, including design optimization, model input calibration, building stock analysis to identify buildings that are candidates for specific programs, or prototype analysis to develop typical savings values. There are two aspects to this—support for cloud computing, and the use of Measures to systematically and efficiently create and index large simulation spaces consisting of related model variants. The cloud provides cheap on-demand processing resources. OpenStudio, and specifically Measures, allow these resources to be used productively.

In December 2016, DOE and the national labs released OpenStudio 2.0, a re-factored re-engineered version of OpenStudio that emphasizes the platform’s commitment to supporting developers and makes the creation and integration of BEM applications and services even easier and more productive.

Project Impact

Despite existing in its current form since 2010, OpenStudio has already had significant uptake and impact. The project has more than 40,000 registered users. More importantly, several significant and diverse applications have already been developed on it. simuwatt Inc.’s simuwatt Energy Auditor is a tablet-based application for performing investment-grade commercial building audits. BetterBricks’ SPARK combines OpenStudio technical analysis with financial parameters to identify and shepherd office building retrofit projects. EDAPT is an Energy Design Assistance Program Administration website developed by Xcel Energy of Colorado. In its first year, EDAPT has saved Xcel over $500,000, while increasing the number of energy consultants and new construction starts in the Xcel’s commercial new construction incentive program. DOE has since worked with Xcel to share share EDAPT with other utilities. The California Energy Commission’s CBECC-Com is a performance-path code compliance tool for California’s Title24. OpenStudio also forms the foundation of DOE’s Commercial Energy Asset Score asset-rating tool and Scout, its energy impacts analysis tool.

The OpenStudio project also led the way for other BTO software development efforts in its use of open-source licensing and agile development processes and tools.

Technical Support

For technical support questions, please search the public Q&A site for an existing answer to your question. If one is not found, please post your question to the site, being sure to include "openstudio" as one of the tags. Both the OpenStudio development team and the larger OpenStudio user community monitors this site.

Recent Publications and Presentations

  • “City Scale Modeling with OpenStudio,” SimBuild 2016, Salt Lake City, UT, August, 2016.
  • “OpenStudio: A Platform for Ex Ante Incentive Programs,” ACEEE Summer Study on Energy Efficiency in Buildings, August 2016.
  • “Scout: An Impact Analysis Tool for Building Energy-Efficiency Technologies,” ACEEE Summer Study on Energy Efficiency in Buildings, 2016.
  • “Electronic Auditing Tool with Geometry Capture,” DoD ESTCP Report EW-201260, 2015.
  • “A Graphical Tool for Cloud Based Building Energy Simulation,” SimBuild 2014, Atlanta, GA, September 2014.
  • “Scaling Building Energy Modeling Horizontally in the Cloud with OpenStudio,” SimBuild 2014, Atlanta, GA, September 2014.
  • “A Parametric Analysis Tool for Building Energy Design Workflows: Application to a Utility Design Assistance Incentive Program,”  ACEEE Summer Study,  August 2014.
  • “Cloud-Based Model Calibration Using OpenStudio,” eSim 2014, Ottawa, Canada, May 2014,
  • “OpenStudio”, Larry Brackney, 2014 BTO Peer Review, Apr. 22, 2014, Arlington, VA.
  • “NREL’s OpenStudio Helps Design More Efficient Buildings,” Innovation Impact Factsheet, July 2014,
  • “Computing Advances Enable More Efficient Buildings,” NREL Continuum, March 2014,
  • “NREL Brings Precision, Savings to Energy Audits,” NREL Press Release, October 2013,