Project website:
-- National Renewable Energy Lab (NREL) – Golden, CO
-- Lawrence Berkeley National Lab (LBNL) – Berkeley, CA
-- Oak Ridge National Lab (ORNL) – Oak Ridge, TN
-- GARD Analytics – Arlington Heights, IL
-- Florida Solar Energy Center (FSEC) – Cocoa, FL
-- Energy Archmage Inc. – Nederland, CO
-- University of Illinois (UIUC) – Champaign, IL
-- Oklahoma State University (OSU) – Stillwater, OK
-- University of Colorado-Boulder (CU-Boulder) – Boulder, CO
-- Big Ladder Software – Denver, CO
-- Objexx Engineering – Needham, MA
-- Empty Crate Software – Denver, CO
-- EffiBEM – Nantes, France
-- Trane Inc. –  La Crosse, WI
-- Autodesk Inc. – San Rafael, CA
-- Carrier Corp. – Charlotte, NC
-- Sefaira (Trimble Navigation Ltd.) – New York, NY
-- Daikin USA – New York, NY
DOE Funding: $2,900,000 in FY20; $83,300,000 to date
Cost Share: $350,000 in FY20; $2,850,000 to date
Project Term: 1997 -
Funding Opportunity: Emerging technologies core funding
Related Projects: EnergyPlus 10X, SpawnOpenStudio, URBANopt, ASHRAE Standard 140, Scout

Project Objective

EnergyPlus™ is DOE’s open-source whole-building energy modeling (BEM) engine, the successor to DOE-2.1E. Under development since 1997, EnergyPlus embodies the state-of-the-art in BEM knowledge in a comprehensive and robust engine that is continuously maintained, thoroughly documented and fully supported. BTO releases two annual updates to EnergyPlus, one in October and one in April — version, 9.3.0 was released in March 2020.

EnergyPlus implements detailed building physics for air, moisture, and heat transfer including treating radiative and convective heat-transfer separately to support modeling of radiant systems and calculation of thermal comfort metrics; calculates lighting, shading, and visual comfort metrics; supports flexible component-level configuration of HVAC, plant, and refrigeration systems; includes a large set of HVAC and plant component models; simulates sub-hourly time steps to handle fast system dynamics and control strategies; and has a programmable external interface for modeling control sequences and interfacing with other analyses. EnergyPlus is tested according to ASHRAE Standard 140 methodology. In 2003, EnergyPlus received an R&D 100 award.

Historically focused on commercial buildings, EnergyPlus has recently been expanded with modeling capabilities relevant to residential buildings and data centers. Information about new features that will be implemented in the coming year is available on the EnergyPlus Documentation page under New Feature Planning.

Supporting Resources

There are a number of support and feedback channels for EnergyPlus. Open, peer-to-peer support is provided via the UnmetHours forum — EnergyPlus developers and advanced users receive email notifications from the forum and most questions are answered within a few hours, if they have not already been asked and answered previously. Several organizations offer on-line and in-person EnergyPlus training. A listing is available on the Building Energy Software Tools Directory. New feature suggestions and bug reports can be filed, discussed and tracked on the GitHub issues page.

Project Impact

EnergyPlus supports a range of building energy-efficiency use cases. Arguably, the one that contributes most directly to energy efficiency is integrated design. BTO tracks the use of EnergyPlus in integrated design via the American Institute of Architects (AIA) 2030 Commitment, a voluntary reporting program that in 2015 comprised over 150 architecture firms and almost 1 billion square feet in U.S. commercial new construction. Analysis of 7,100 projects submitted from 2013 to 2015 shows that EnergyPlus use has grown to 10% of modeled projects — 61% of projects use BEM — and that projects using EnergyPlus average 51% EUI reduction over CBECS 2003 baseline, relative to 44% for projects using all BEM tools and 29% for projects using no BEM tools. Using these figures, we project that integrated design using EnergyPlus has the potential to save 800 TBTU a year by 2030.

EnergyPlus has had significant recent uptake by both end users and commercial vendors. The last several versions have averaged over 43,000 downloads per update. Recent years have also seen the the release of several new third-party tools and user interfaces, including offerings from Sefaira, Autodesk, and Trane. A more complete listing of EnergyPlus-based applications and services can be found at the new Building Energy Software Tools Directory.

EnergyPlus directly supports a number of public and private-sector tools and services.
EnergyPlus directly supports a number of public and private-sector tools and services. It supports additional applications and services via the OpenStudio platform.
The OpenStudio platform supports a range of public and private-sector end-user applications and services.
The OpenStudio platform supports a range of public and private-sector end-user applications and services serving a variety of use-cases and constituencies.


DOE Technology Manager: Amir Roth (project management, not technical support)
Principal Investigator: Luigi Gentile Polese, NREL (project management, not technical support)

Publications and Presentations

  • R. Zhang, T. Hong. Modeling and Simulation of Operational Faults of HVAC Systems using EnergyPlus, ASHRAE/IBPSA-USA Building Simulation Conference SimBuild, August 10-12, 2016, Salt Lake City, UT.
  • J. Glazer. Development of Maximum Technically Achievable Energy Targets for Commercial Buildings Ultra-Low Energy Use Building Set. 1651-RP, ASHRAE, December 2015.
  • T. Hong, K. Sun, R. Zhang, R. Hinokuma, S. Kasahara, Y. Yura. Development and Validation of a New Variable Refrigerant Flow System Model in EnergyPlus, Journal of Energy and Buildings, September 2016.
  • M. Witte, E. Lee, L. Gu, R. Raustad, T. Hong, and D. Kang. Strengthening EnergyPlus to Enable Advanced Building Energy Models, Michael J. Witte, Edwin S. Lee, Lixing Gu, Richard Raustad, Tianzhen Hong, and Daeho Kang, ASHRAE/IBPSA-USA Building Simulation Conference, September 12, 2014, Atlanta, GA.