ThermX — 2D Heat Transfer Analysis

What It Solves

ThermX calculates temperature distributions, heat flux, U-factors, ψ-values (linear thermal transmittance), and condensation risk (fRsi) in 2D cross-sections of building construction details:

🪟

Window Frames

Frames, glazing spacers, curtain wall mullions — full thermal performance per NFRC and CEN methods.

🧱

Wall Sections

Steel stud walls, masonry with insulation, EIFS/ETICS systems, sandwich panels.

🏗️

Thermal Bridges

Balcony connections, slab edges, lintels, parapets — calculate ψ-values per EN ISO 10211.

📐

Any 2D Detail

Any cross-section with multiple materials and boundary conditions. If you can draw it, ThermX can solve it.

Features

✏️

Geometry Editor

Polygon and rectangle drawing tools
Snap-to-grid, vertex editing, drag-to-move
Boolean operations (union, subtract, split)
Overlap detection with visual warnings
Multi-select with Tab cycling
Layers and groups

🧪

37 Built-in Materials

EN ISO 10456 conductivity values
Solids, insulations, glazing, gases
Custom materials with user-defined properties
Color-coded canvas rendering
Materials legend overlay

🌡️

Boundary Conditions

Convective, fixed temperature, adiabatic
CEN and NFRC preset libraries
Multi-edge selection
Color-coded edge rendering with legend

🔺

Automatic Meshing

Delaunay triangulation + Ruppert refinement
spade (Rust CDT compiled to WebAssembly)
Min/max edge length sliders (0.5–50 mm)
Min angle and max area quality controls
Real-time mesh preview with quality coloring

⚡

Multiple Solvers

Conjugate Gradient (CPU, Web Worker)
Cholesky direct solver (small models)
WebGPU — GPU-accelerated in browser
wgpu native — Vulkan/Metal/DX12 on desktop
Double-single f64 emulation (~48-bit precision)
Auto-detection: GPU → CPU fallback

📊

Results & Analysis

Temperature color maps (WebGL-rendered)
Isotherm contour lines
Heat flux vectors
U-factor calculation (ISO 15099)
ψ-value / L2D (EN ISO 10211)
fRsi condensation risk factor

📄

Sheet Views & PDF

Dedicated Sheets tab with paper preview
Viewport, text, dimension, arrow, table tools
Title block editor
PDF export (vector text, high-DPI viewports)

📁

Import & Export

THMX (LBNL THERM) — full read/write
DXF import and export
DWG import (desktop, via LibreDWG)
PNG screenshot export
Built-in example files

Material Database

37 built-in materials with thermal conductivity values from EN ISO 10456. Create custom materials with user-defined properties.

Concrete (1.80)

Lightweight Concrete (0.50)

Aerated Concrete (0.12)

Solid Brick (0.77)

Perforated Brick (0.44)

Granite (2.80)

Cement Mortar (1.40)

Steel (50.0)

Stainless Steel (17.0)

Aluminum (200)

Copper (380)

Insulation (0.040)

EPS (0.037)

XPS (0.034)

Mineral Wool (0.035)

PIR/PUR Foam (0.023)

Phenolic Foam (0.021)

Glass (1.00)

Low-E Glass (1.00)

Wood (0.17)

PVC (0.16)

Polyamide (0.25)

Plasterboard (0.25)

Air (0.024)

Argon (0.016)

Krypton (0.009)

Values shown: thermal conductivity λ in W/(m·K). Plus 11 more materials included.

Technical Details

UI & Rendering	TypeScript, HTML5 Canvas, PixiJS v8 (WebGL)
Solver Engine	TypeScript (CPU), WGSL compute shaders (GPU)
Meshing	spade (Rust → WebAssembly, 185 KB)
Desktop Shell	Tauri 2 (Rust) — not Electron
GPU Backend	WebGPU (browser) / wgpu v24 (native Vulkan/Metal/DX12)
GPU Precision	Double-single f64 emulation (~48-bit mantissa via vec2<f32>)
Build	Vite, npm, Rust (Cargo)
Codebase	~10,700 lines TypeScript + ~700 lines Rust
Installer Size	3.3–6.9 MB (varies by platform)
License	Proprietary (one-time purchase, free updates within major version)

Platform Support

Feature	🌐 Browser	🐧 Linux	🪟 Windows	🍎 macOS
Meshing (spade WASM)	✓	✓	✓	✓
CPU Solver	✓	✓	✓	✓
GPU Solver (WebGPU)	✓	✓*	✓	✓
GPU Solver (wgpu native)	—	✓	✓	✓
DWG Import	—	✓	✓	✓
Native File Dialogs	—	✓	✓	✓

* WebGPU in Tauri on Linux requires a non-snap browser or Chromium with WebGPU flags enabled. The native wgpu solver works regardless.

Standards Compliance

EN ISO 10211 — Thermal bridges in building construction — Heat flows and surface temperatures
EN ISO 10077-2 — Thermal performance of windows, doors and shutters — Numerical method for frames
EN ISO 10456 — Building materials and products — Hygrothermal properties — Tabulated design values
ISO 15099 — Thermal performance of windows, doors and shading devices — Detailed calculations
NFRC — National Fenestration Rating Council simulation methodology

ThermX vs. THERM

	ThermX	LBNL THERM 8
Platforms	Windows, macOS, Linux, Browser	Windows only
GPU Acceleration	✓ WebGPU + wgpu	❌
THMX File Support (Read & Write)	✓	✓
PDF Reports	✓	✓
DXF Import/Export	✓	✓
ψ-value (PSI)	✓	✓
fRsi Condensation Risk	✓	✓
Technology	Tauri	.NET WinForms
Installer Size	~5 MB	~138 MB
Price	€10 one-time	Free