RESFEN Software Downloads

Version 6.0.16 Beta
Released: December 21, 2012

Release Notes:

Program Changes

Updates from RESFEN 5.0

The primary change between RESFEN 5 and RESFEN 6 is that some of the underlying modeling assumptions were changed to be consistent with the Energy Star 2008 analysis done by LBNL. The new modeling assumptions are documented in the RESFEN 6 User Manual in Chapter 6. The Energy Star 2008 Modeling assumptions compared to the RESFEN 5 assumptions are documented in this RESFEN Knowledge Base article.

Alaska Locations

Three of the entries for Alaska in the Location Library have been deleted (Barrow, Bettles, and Kotzebue) due to bad data in the weather files. The ID numbering of the remaining Locations was not changed, so there are ID "gaps" for those deleted locations.

Program Changes

WINDOW 6.3 Window Libraries

RESFEN 6.0 can read the current version of WINDOW 6.3 database.

SI and IP Units

RESFEN has the ability to display input and results in both SI and IP units. This is a very new feature and users are encouraged to test it’s functionality and accuracy, in particular in the “Window by Orientation” results.


RESFEN5 allows multiple House Library records to be selected in the List View and then simulated as a group by clicking on the lightning bolt Calc toolbar button.

Fixed Bugs

SI Units

The option of using SI units for input and results was not working properly. This has been fixed.


Even when the skylight area was set to zero, in previous versions there would be a contribution to heating from skylights. This has been fixed.

Results by Orientation

Calculating results by orientation (using the double lightning bolt toolbar icon) was not working properly. This has been fixed.

Location Library

Changing the Climate Zone using the pulldown list feature did not "stick" in previous versions. This field is currently only informative and does not control any options in the program, but when it is set, the program now saves that value.

Version 5.0
Released: June 25, 2007

Release Notes:

RESFEN 5.0 calculates the same results that RESFEN 3.1 calculates.

The significant changes that differentiate RESFEN5 from RESFEN 3.1 are listed below. Some of these changes affect program results. A major change to the program is that it is now based on a database structure (Microsoft AccessTM), which allows for a much more flexible file system for storing data.

Addition of Libraries:

RESFEN5 is now made up of a set of “Libraries” which is where information is stored and input. Each library has a “List” view, where all the records (rows) in the library can be viewed, and a “Detail” view, where all the data (or fields) in each record can be viewed. See the RESFEN 5.0 User Manual for a more complete discussion of the library structure.

  • House Library: The House Library in RESFEN5 is similar to the main screen in RESFEN 3.1, but with the ability to see multiple input sets at the same time from the List View.
  • Locations Library:  RESFEN5 has a Locations Library which can be used to create new locations that reference specific weather data and insulation packages. In the default database that is installed, called RESFEN5.mdb, there are 240 locations for the United States, as well as four for Canada. There are also other databases (for Canada, Chile and China) with more locations defined.
  • Window Library:  RESFEN5 has a Window Library that allows data for specific windows to be imported from the WINDOW5 program. A default set of WINDOW5 data is installed with RESFEN5, and other data can be imported as needed or provided by manufacturers or other sources.
  • Packages Library:  RESFEN5 has a Packages Library, which allows the user to create new insulation packages that can be associated with a Location to create customized modeling situations.
  • Results Library: RESFEN5 has a Results Library, which allows the user to view results from multiple runs, as well as export those results to comma separated text files that can be imported into a spreadsheet program.
  • Electric Rates Library: RESFEN5 has an Electric Rates Library, which allows the user to add new rates or change existing rates. The default library contains one rate for each US state, based on data from the Energy Information Administration
  • Gas Rates Library: RESFEN5 has a Gas Rates Library, which allows the user to add new rates or change existing rates. The default library contains one rate for each US state, based on data from the Energy Information Administration


You must uninstall previous RESFEN 5.0 versions before installing this version. Archive to another directory any MDB files that you do not want to be overwritten. And then after installation, move the MDB files back into the RESFEN program directory if you want to access them.