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Next generation building energy simulation program that builds on the most popular features and capabilities of BLAST and DOE-2. EnergyPlus includes innovative simulation capabilities including time steps of less than an hour, modular systems simulation modules that are integrated with a heat balance-based zone simulation, and input and output data structures tailored to facilitate third party interface development. Recent additions include multizone airflow, electric power simulation including fuel cells and other distributed energy systems, and water manager that controls and report water use throughout the building systems, rainfall, groundwater, and zone water use.


energy simulation, load calculation, building performance, simulation, energy performance, heat balance, mass balance


EnergyPlus has been tested against the IEA BESTest building load and HVAC tests. Results are available under Testing and Validation on the EnergyPlus web site.

Expertise Required

High level of computer literacy not required; engineering background helpful for analysis portions.


Over 85,000 copies of EnergyPlus downloaded since it was first released in April 2001.


Mechanical, energy, and architectural engineers working for architect/engineer firms, consulting firms, utilities, federal agencies, research universities, and research laboratories.


EnergyPlus uses a simple ASCII input file. Private interface developers are already developing more targeted / domain specific user-friendly interfaces. See the EnergyPlus web site for up-to-date information on interfaces and other tools for EnergyPlus.


EnergyPlus has a number of ASCII output files - readily adapted into spreadsheet form for further analysis.

Computer Platform

Available for Windows XP/Vista, Mac OS, and Linux.

Programming Language

Fortran 2003


Accurate, detailed simulation capabilities through complex modeling capabilities. Input is geared to the 'object' model way of thinking. Successful interfacing using IFC standard architectural model available for obtaining geometry from CAD programs. Extensive testing (comparing to available test suites) is completed for each version and results are available on the web site. Weather data for more than 1250 locations worldwide available on the web site.


Text input may make it more difficult to use than graphical interfaces.



U S Department of Energy


EE-2J, Building Technologies
1000 Independence Avenue, SW
Washington, DC 20585-0121
United States







EnergyPlus Version 3.1.0 was released in April 2009. EnergyPlus and weather data for more than 2000 locations worldwide can be downloaded at no cost from the EnergyPlus Web site.