IDD
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EnergyPlus Input Data Dictionary (IDD).
At a glance
| Original creator | EnergyPlus (U.S. Department of Energy) |
| Purpose | The EnergyPlus input data dictionary: every object an input file may contain, with each field's type, units, allowed values, default and limits. |
| Extensions | .idd |
| Poka parser | poka-idd |
| Viewer | poka-tree-viewer |
| Depth tier | Parser with a shared viewer (see Depth tiers) |
| Breadth tier | B2 Broad (see Breadth tiers) |
How much Poka reads
B2 Broad. The common content of the current and the common older versions is decoded. Some named features or versions are not, and are listed.
Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-16: poka-idd src/lib.rs (parse_idd, field_info, build_ast, 20+ unit tests) and tests/samples.rs; corpus has the EnergyPlus 25.1.0 Energy+.idd (108,150 lines, about 850 objects, about 23,800 fields) and 8 IDFVersionUpdater and earlier IDDs from V7.2 to V25.1. The parser models every directive in all corpus versions (a test asserts none falls into the unmodelled bucket). The viewer tree is capped at 12,000 nodes, and counting nodes in the 25.1 file suggests roughly half of the dictionary would be cut (estimate, not run).
What Poka does not read
- object memo and field note text (descriptions) are parsed but not shown in the tree
- min-fields, format and retaincase directives are parsed but not shown
- on a full-size IDD the 12,000-node cap leaves later groups and objects without fields or missing, with the truncated flag set
- field detail nodes (choices, object-lists, references, bounds, IP units) are dropped once the cap is reached
- no search or cross-reference navigation between an object-list field and the objects that provide its reference
Background
EnergyPlus is a whole-building energy simulation program whose development is funded by the U.S. Department of Energy Building Technologies Office. It is a console program that reads its input from text files; the IDD, shipped as Energy+.idd, is the schema those files follow, and the EnergyPlus documentation describes its conventions (\field, \type, \units and the other annotations). Poka shows the dictionary as a tree of groups, objects and fields with each field's choices, references and limits, so a reader can look up what "Field 7" of an object means. The memo and note text is parsed but not shown, and the tree stops at 12,000 nodes, so a full-size dictionary is cut short.
Versions
| Version | Identifier | Poka | Note |
|---|---|---|---|
| EnergyPlus IDD | !IDD_Version |
Read |
Libraries
Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.
- eppy (candidate; MIT; Python; https://eppy.readthedocs.io/en/master/eppy.EPlusInterfaceFunctions.html) — Has parse_idd and iddgroups modules that read the IDD; repo is MIT except eppy/epconversion.py (MPL-2.0), per https://github.com/santoshphilip/eppy.
- eplusr (candidate; MIT; R; https://search.r-project.org/CRAN/refmans/eplusr/html/Idd.html) — Idd class documented as providing parsing and printing of IDD files; licence from https://github.com/hongyuanjia/eplusr.