RSS Feed
EnergyPlus V8.2.0 Release
Posted by Michael J. Witte on 01 October 2014 12:00 AM

The U.S. Department of Energy (DOE) has released EnergyPlus V8.2.0, the first release of EnergyPlus built on C++ source code.  New feature highlights are listed below.  For more information about EnergyPlus, please visit

Installers and source code for V8.2.0 are available at

The EnergyPlus Development Team

Highlights of this release (V8.2.0)

Core Changes to EnergyPlus
*Internal simulation engine code translated from FORTRAN to C++ to spur the evolution of EnergyPlus through improved interaction with a larger community through a more popular code base, and improved access to code libraries for performance and enhanced capabilities.

*Language change initially caused a slightly slower codebase due to translation overhead, however several restructuring efforts in the code eventually led to EnergyPlus V8.2.0 being faster than V8.1 in many tests cases.

*Development transitioned to GitHub, where the source code is to be made fully public in the spirit of the open source license.

*Bug fixes throughout.

Building Envelope
*Integrated slab calculation now allow improved simulation of ground heat transfer
HVAC, Plant and Refrigeration
*Improved sizing algorithm for including fan heat in cooling coil calculations
*Improved sizing input options for scaling autosized values
*Additional plant load dispatch algorithms based on meeting component part-loading targets
*New models for single-sided natural ventilation with multiple openings
*New on/off fan option for unit heater and unit ventilator
*New fault model for coil fouling
*DOAS direct to zonal water-to-air heat pumps
*Expanded support for table lookup for plant equipment performance
*New zone air mass flow balance option (partially link HVAC flows with zone mixing and infiltration)
*Ice storage curve-fit tool

*Windows 7 & 8: 64-bit version (32-bit may be available via Helpdesk)
*Linux (Ubuntu 14.04 and compatible) 64 bit versions; (32-bit and RHEL-compatible versions may be available via Helpdesk)
*Mac OSX 10.9 64 bit versions
*EnergyPlus V8.2.0 has been tested on all of these platforms

Read more »

Update on EnergyPlus Releases
Posted by Michael J. Witte on 23 April 2014 05:16 PM

For the past several years there have been two annual releases of DOE’s energy simulation engine EnergyPlus, in April and October. In 2014, we are skipping the April release. EnergyPlus has recently been translated from FORTRAN to C++ (see announcement at, and additional time was needed to complete the transition which included not only the program itself but also its development environment and processes. The transition is expected to be fully complete in the summer. The next EnergyPlus release will be in the fall of 2014, and we hope to announce a firm date—as well as new features—in the next month or two.

Read more »

EnergyPlus 8.1 Updated
Posted by Edwin Lee on 24 January 2014 04:22 PM

EnergyPlus Helpdesk Subscribers:

The EnergyPlus Development Team has released an updated version of EnergyPlus 8.1.  The new build (009) features bug fixes that were addressed in the period following the original October 2013 release of 8.1.  If you are using EP-Launch, the tool should also inform you of the available update shortly.  The download is available at the EnergyPlus home page (

Thank you!

Read more »

ASHRAE Design Conditions posted on EnergyPlus helpdesk
Posted by Linda Lawrie on 27 November 2012 03:24 PM

EnergyPlus SizingPeriod:Designday object definitions have been posted on the EnergyPlus helpdesk.

The ASHRAE Handbook of Fundamentals specifies design conditions for 5500+ locations.  These zip files have "macro defined" sets for each in EnergyPlus V7.1 (and later) format. Included in the articles are the "keys" to finding the location in the larger .imf files.

Climatic Design Conditions are discussed in the ASHRAE Handbook of Fundamentals, Chapter 14, 2009 edition.

Annual Design Conditions are (represented by the attachments in EnergyPlus SizingPeriod:Designday form) also discussed in this chapter.

Monthly Design Conditions (represented by the attachments in EnergyPlus SizingPeriod:Designday form) and how they are to be used are also discussed in this chapter. Monthly design conditions for dry bulb temperature (with mean coincident wet bulb temperature) and wet bulb temperature (with mean coincident dry bulb temperature) for .4% and 2% are included.

The links to the postings are:

Read more »

Important Weather Converter files missing from install
Posted by Linda Lawrie on 09 June 2012 04:32 PM

Two important files missing from the install for the weather converter program.  Without them, the full set of statistics will not be produced.

Download and instructions:


Read more »

Multiple version update programs posted for all platforms.
Posted by Linda Lawrie on 05 June 2012 11:32 PM

Attachments to three knowledgebase articles allow you to download the multiple version programs to convert your older IDFs to current release (or any release in between).

Read more »