New Version -- EnergyPlus v3.1 and OpenStudio v1.0.3 now available

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EnergyPlus Version 3.1 Available

The latest release of the EnergyPlus building energy simulation program,
Version 3.1, is now available in versions for Windows, Linux, and Mac
operating systems. A few key new features include simplified rectangular
geometry for walls, roofs, ceilings, floors, windows, and shading;
thermochromic windows; upgraded UFAD model; Standard 62.1 demand control
ventilation; cool beam HVAC model; new tabular reports to support LEED
EA Credit 1 forms; and new post-processing utility to combine Standard
90.1 Appendix rotation results. We have updated and extended
capabilities throughout the existing building envelope, daylighting, and
HVAC equipment and systems portions of the program.

EnergyPlus V 3.1 is available at no cost from the EnergyPlus web site: .

OpenStudio plugin for Google SketchUp: The OpenStudio
is a free plugin
for the GoogleSketchUp 3D drawing program. The plugin makes it easy to
create and edit the building geometry in your EnergyPlus input files.
The plugin also allows you to launch EnergyPlus simulations and view the
results without leaving SketchUp.

EnergyPlus Example File Generator: A Web-based service is available that
creates and runs EnergyPlus input files for simple models of commercial
buildings. The input files (and annual results summary files) are sent
to your e-mail address as attachments. This is a pilot project and is
currently made available only as a BETA service. You can access the
service and customize the characteristics of the building you want to
model on the EnergyPlus Example File Generator Application
(pop-ups must be enabled).

The set of example input files now includes full-blown models of typical
new construction (drawn from the DOE Commercial Benchmarks project).

What's New in Version 3.1?


* Users can now define surfaces as simple rectangles (Simple
Rectangular Surfaces) for walls, roofs, ceilings, floors, windows,
doors, glazed doors, and shading.

* New detailed surfaces objects (Wall:Detailed,
RoofCeiling:Detailed, FloorDetailed).

* InputProcessor can now output defaults, autosizing, and
autocalculation statistics.

* New Constant Schedule allows simpler schedule definition.


* New variables for reporting visual discomfort: Time Exceeding
Glare Index Setpoint at Ref Point 1 and Time Exceeding Glare Index
Setpoint at Ref Point 2.

Zone Model

* Thermochromic windows can now be modeled.

* New Adiabatic Surface option for Outside Boundary Condition.

* New Sinusoidal option for Other Side Coefficient Boundary
Conditions allows users to apply a sinusoidal schedule to the surface
boundary conditions.

* Two new simplified infiltration models added: Sherman-Grimsrud
and AIM-2.

* Ventilated slab has additional SerialSlab system configuration
option, allowing multiple ventilated slabs in different zones to be
connected in series.

Natural and Mechanical Ventilation

* UFAD model upgraded.

* AirflowNetwork wind speed model for height-dependency

* Air Distribution System Model includes more components:
heating coil and three heat exchangers.

* Demand Control Ventilation model based on ventilation rate
procedure of Standard 62.1-2007 procedure of Standard 62.1-2007.


* New Unitary Air-to-Air Heat Pump and Packaged VAV HVAC

* Improved control of unitary equipment under low-load
conditions (Furnaces, Heat Pumps, PTAC, PTHP, and Window AC).

* Furnaces/Unitary Systems now allow high humidity control with
cycling supply air fan systems.

* Cool Beam model added.

* Option to size system flow rate and terminal units based on
minimum ventilation requirements added; other zone equipment will be
sized on zone loads

* Fan:OnOff now models multi-speed fan performance.

* Minimum stops on VAV terminals with reheat can now be

* SensibleAndLatent and Desiccant Heat Exchangers now have
economizer lockout option.

* Revised air-bypass logic for HeatExchanger:AirToAir:FlatPlate
to match the logic used for HeatExchanger:AirToAir:SensibleAndLatent.

* Refrigeration racks and systems now accept either the name of
a case or caselist, and compressor or compressorlist.

* Improved moisture condensation controls for Low Temperature
Radiant systems.

* EvaporativeCooler:Direct:ResearchSpecial model added.

* Water consumption model for Indirect Evaporative Cooler
extended. Secondary air flow rate can now be autosized.


* New tabular reports to support LEED EA Credit 1 forms.

* Tabular reports now can be in Inch-Pound units.

* Improved diagnostics, warnings, and informative messages

* Output:Reports object converted to simpler
Output:Surfaces:List, Output:Surfaces:Drawing objects.


* New AppGPostProcess utility in combination with
Building:Compliance object averages the results from four building
rotation runs for Standard 90.1 Appendix G compliance.

* Datasets can now be directly opened from a menu in IDFEditor.

* Weather Converter updated to allow more custom date formats.

* Weather Converter now can include rainfall information (where
available) in EnergyPlus weather data files.

Documentation and Guides

* Input/Output Reference and Engineering Reference updated and
extended for all new features and updates and renaming. Total
documentation now exceeds 4,000 pages.

And many other enhancements and speed improvements throughout.

for a complete list of new
features added in this and previous versions.

Suggestion: get as much memory as possible in your computer for running
EnergyPlus. A recent team upgrade from 1.8GHZ machine with 768MB memory
to a 2.1GHZ machine with 2GB memory caused one file to go from a full
annual simulation (5 zones) at about 8 minutes to a 2-1/4 minute run on
the newer machine.

Update on User Interfaces and Tools?

Many user interfaces that create and run EnergyPlus input files and
display results graphically are available (Demand Response Quick
Assessment Tool, DesignBuilder, Easy EnergyPlus, EFEN, Hevacomp, and
HLCP) and under development (ComFen, TREATPlus and EPlusInterface).
Check our web site (
) for up-to-date
information on these and other interfaces.

Utilities and tools for creating, editing, and running input files that
come with EnergyPlus include IDF Editor, EP-Launch, and HVAC-Diagram
). Third party tools for
creating, editing, and displaying EnergyPlus input files are also
available, including DrawBDL, EcoTect, EnergyPlugged, ESP-r, Green
Building Studio, EzDrawPlus, IFCtoIDF, TSe+, and EzPlus-Parm. See
for more

EnergyPlus Training Workshops

We will continue to offer training workshops throughout 2009. For more
information, please see:

What's going on in V3.1.0?

Will there be any considerable difference between version 3.0 and 3.1?

Yes.... and no. As always, there are a number of new features and bug
fixes. The highlights of features for this version are listed below-see
for a complete list of new
features added in this and previous versions.

How about IDF and IDD? Do they remain unchanged?

There will be some changes in the IDD and reflected in IDFs.
Particularly for any new features, there will be new objects. Your best
option is to use the included Transition program if you want to use any
older version files.

Is version 3.1 backward compatible? Can I run v3.0 file in v3.1?

For many options, the answer is yes. However, there are several changes
that require you to use the transition program for V3.1. EP-Launch can
check the selected file (if there is a version object) and you can
launch the Transition program from the EP-Launch "File" menu. You can
also view the ObjectStatus spreadsheet in the root folder of the
installed version. This file has detailed explanations of changes to the
objects. There is also a new option for the transition program that
allows you to supply a list of files and it will convert them for you.
The transition program is described more fully in the Auxiliary Programs

EnergyPlus Weather Data

Weather data for more than 2000 locations worldwide are available on the
EnergyPlus web site:
(New data for China,
Australia, and Poland should be available soon.)

If you know of other weather data for your country that you'd be willing
to share with the EnergyPlus user community, please contact Dru Crawley
(Drury.Crawley at ).

EnergyPlus Helpdesk

A helpdesk system has been set up for managing EnergyPlus user support
requests. The helpdesk system includes a download area, a knowledge base
and troubleshooting area. To submit new support requests (tickets) or
search the knowledge base, please go to
. You may also submit new issues,
files and reply to tickets via e-mail at EnergyPlus-Support at
. This address has been linked to
the helpdesk since early May 2008. This is the best way to get your
specific EnergyPlus questions answered.

EnergyPlus_Support Group at YahooGroups

Are you a commercial or academic user of EnergyPlus? Join more than
2,000 EnergyPlus users in the user-to-user email group on YahooGroups-a
place to ask questions and share information with other EnergyPlus
users. The YahooGroup also provides a searchable archive of all 7+ years
of discussion. You can also upload files to share with other users.
While the EnergyPlus development team does monitor the YahooGroup list,
the best place for individualized support is the EnergyPlus Helpdesk

The main web page for the group is:

To subscribe, send an email message to:

EnergyPlus_Support-subscribe at

If you hate to constantly receive email, you can edit your YahooGroup
membership to only send a daily digest of messages.

Building Energy Simulation User News

Want to keep up to date on EnergyPlus and other building simulation
tools? Subscribe to the bi-monthly electronic newsletter for users of
EnergyPlus, DOE-2, BLAST, GenOpt, SPARK, and Energy-10. See


Join the free e-mail list for users of all building energy simulation
programs. Ask other knowledgeable simulation program users your
questions--about EnergyPlus and other simulation programs. See

for information on joining this email list.


The EnergyPlus Team

Drury.Crawley at EE.DOE.GOV's picture
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