LibraryFEMTherm

C++20 static library for reading, writing, and manipulating THERM (.thmz) files. Provides data structures and serialization for thermal models, materials, boundary conditions, gases, glazing systems, and CMA data. Optional Python bindings via pybind11.

Requirements

• CMake 3.8+
• C++20 compiler (MSVC 2022, GCC 11+, Clang 14+)
• Ninja or Visual Studio generator
• Python 3.11+ (only when building Python bindings)

Building

CMake presets

CMakePresets.json ships six visible configure presets plus three hidden inheritance bases. Use the default-* presets for normal builds, local-* to consume sibling working copies of LBNL deps, and python-* to also build the Python bindings:

Preset	Description	Python bindings	C++ tests
default-debug / default-release	C++ only. Fetches all dependencies from declared remotes.	OFF	ON
local-debug / local-release	C++ only, but consume sibling ../LBNLCPPCommon and ../FileParse working copies when present.	OFF	ON
python-debug / python-release	C++ with Python bindings. Fetches all dependencies from declared remotes.	ON	ON

Missing siblings under local-* fall back to the declared remote automatically, so local-* is safe to invoke even if you don't have the LBNL siblings checked out.

cmake --preset default-release
cmake --build build/default-release --config Release --parallel
ctest --test-dir build/default-release -C Release --output-on-failure

For Python bindings:

cmake --preset python-release
cmake --build build/python-release --config Release --parallel
ctest --test-dir build/python-release -C Release -V

CLion and VS Code automatically detect these presets.

Per-machine compiler presets (CMakeUserPresets.json)

To use a specific compiler (vs2022-release, gcc-13-debug, clang-18-release, etc.), each developer maintains their own CMakeUserPresets.json next to CMakePresets.json. It is gitignored, read automatically by CMake (and CLion, VS Code, etc.), and stays on the developer's machine.

Personal presets inherit from one of the shipped presets (usually local, which gives you sibling-repo overrides for free, or python if you want bindings) and override whatever they want. A complete realistic example -- building with WSL Clang on a Windows machine, with CLion 2023.2+ routed through the WSL toolchain automatically:

{
    "version": 6,
    "configurePresets": [
        {
            "name": "clang-release",
            "displayName": "clang (Release)",
            "inherits": "local",
            "generator": "Ninja",
            "binaryDir": "${sourceDir}/build/clang-release",
            "cacheVariables": {
                "CMAKE_C_COMPILER":   "clang",
                "CMAKE_CXX_COMPILER": "clang++",
                "CMAKE_BUILD_TYPE":   "Release"
            },
            "vendor": {
                "jetbrains.com/clion": {
                    "toolchain": "WSL"
                }
            }
        }
    ]
}

Manual configuration (without presets)

cmake -G "Visual Studio 17 2022" -A x64 -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --config Release

Add -DBUILD_PYTHON_BINDINGS=ON to include Python bindings.

CMake options

Option	Default	Description
BUILD_PYTHON_BINDINGS	OFF	Build Python bindings via pybind11
BUILD_LibraryFEMTHERM_TESTING	ON	Build C++ test targets

Python bindings

Install from PyPI:

pip install libraryfemtherm

Or build from source with BUILD_PYTHON_BINDINGS=ON (see above).

import pylibraryfemtherm as fem

# Load a THMZ file
model = fem.load_model_from_zip_file("sample-sill.thmz")
print(f"Polygons:   {len(model.polygons)}")
print(f"Boundaries: {len(model.boundary_conditions)}")

# Save to XML string
xml = fem.save_model_to_string(model)

# Save to a new THMZ file
fem.save_model_to_zip_file(model, "output.thmz")

# Work with ZIP contents directly
contents = fem.zip.unzip_files("sample.thmz", [fem.zip.MATERIALS_FILE_NAME])
db = fem.MaterialsDB()
db.load_from_string(contents[fem.zip.MATERIALS_FILE_NAME])

For comprehensive Python API documentation with examples, see doc/python.md.

Project structure

src/
  BCSteadyState/     # Steady-state boundary conditions
  BCTransient/       # Transient boundary conditions
  CMA/               # CMA (Component Modeling Approach) data
  Common/            # Shared utilities
  Gases/             # Gas properties and mixtures
  Materials/         # Material definitions (solid, cavity, radiation)
  THMZ/              # ThermModel, geometry, preferences, properties, zip I/O
  LibraryUtilities/  # Common helpers
  Schemas/           # XML/JSON schemas
python/
  src/               # pybind11 binding source files
  tests/             # pytest test suite
tst/
  units/             # C++ Google Test files
  products/          # Test THMZ data files
cmake/               # CMake macros and compiler config

Dependencies (fetched automatically)

• FileParse - XML/JSON serialization
• LBNLCPPCommon - Common utilities
• miniz - ZIP compression
• pybind11 v2.13.6 - Python bindings (optional)
• Google Test v1.13.0 - Testing (optional)