The ExpandObjects program uses HVACTemplate objects in the
IDF file to “expand” them into full fledged objects for
EnergyPlus. Read more details of the systems and the
individual fields in the HVACTemplate objects in the Input
Output Reference document.
ExpandObjects also processes GroundHeatTransfer objects,
sends an input file to the Slab and Basement preprocessors,
and replaces ground heat transfer boundary condition fields in
building surface objects. Read more details of the ground heat
transfer processing in the Input Output Reference.
Technically speaking, the ExpandObjects program is a
preprocessor that is currently used with the HVACTemplate
objects. The preprocessor reads an idf file
and generates an expanded.idf file (usually with the extension
.expidf). The original idf file contains
objects that will be read by the preprocessor and those that
are ignored by the preprocessor. The objects read can be
either commented out or left as is. The objects created by the
preprocessor in the expanded.idf file should require no
further preprocessing. The preprocessor does not read the
EnergyPlus Data Dictionary file (Energy+.IDD) and does limited
validation. Most of the object values that are created are
“passed” through from input objects. This allows EnergyPlus to
provide most of the validation. If errors are found, error
messages are passed to the EnergyPlus program using the
Output:Preprocessor object. These errors will be shown in the
usual EnergyPlus error file. When used with EP-Launch, the
expanded.idf file is renamed to the original file name with
the extension expidf.
Introduction[LINK]
The ExpandObjects program uses HVACTemplate objects in the IDF file to “expand” them into full fledged objects for EnergyPlus. Read more details of the systems and the individual fields in the HVACTemplate objects in the Input Output Reference document.
ExpandObjects also processes GroundHeatTransfer objects, sends an input file to the Slab and Basement preprocessors, and replaces ground heat transfer boundary condition fields in building surface objects. Read more details of the ground heat transfer processing in the Input Output Reference.
Technically speaking, the ExpandObjects program is a preprocessor that is currently used with the HVACTemplate objects. The preprocessor reads an idf file and generates an expanded.idf file (usually with the extension .expidf). The original idf file contains objects that will be read by the preprocessor and those that are ignored by the preprocessor. The objects read can be either commented out or left as is. The objects created by the preprocessor in the expanded.idf file should require no further preprocessing. The preprocessor does not read the EnergyPlus Data Dictionary file (Energy+.IDD) and does limited validation. Most of the object values that are created are “passed” through from input objects. This allows EnergyPlus to provide most of the validation. If errors are found, error messages are passed to the EnergyPlus program using the Output:Preprocessor object. These errors will be shown in the usual EnergyPlus error file. When used with EP-Launch, the expanded.idf file is renamed to the original file name with the extension expidf.
Documentation content copyright © 1996-2026 The Board of Trustees of the University of Illinois and the Regents of the University of California through the Ernest Orlando Lawrence Berkeley National Laboratory. All rights reserved. EnergyPlus is a trademark of the US Department of Energy.
This documentation is made available under the EnergyPlus Open Source License v1.0.