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Calculates two-dimensional transient and steady-state heat conduction within objects that can be described in a rectangular grid. It is well adapted to the following applications:

  • General heat conduction problems
  • Analysis of thermal bridges
  • Calculation of U-values for building construction parts
  • Estimation of surface temperatures (surface condensation risks)
  • Calculation of heat losses to the ground from a house
  • Optimization of insulation fitting
  • Analysis of floor heating systems
  • Analysis of window frames
The time to generate the complete input for a reasonably complicated case is less than 10 minutes after a few hours' experience of the program. The following list shows some features:
  • An integrated pre-processor facilitates the input procedure
  • Material properties may easily be edited and added. Several material list are available. The default list (Default.mtl) contains about 200 common building materials. The list General.mtl has over 1200 defined materials. Another file with over 200 materials (in German) from the German standard DIN (Deutsches Institut f�r Normung, DIN V 4108-4) is also available.
  • A simple numerical mesh generation option is available. The mesh can easily be changed.
  • Any structure consisting of adjacent or overlapping rectangles with any combination of materials may be simulated. Up to 62500 (250�250) nodes may be used.
  • Boundary conditions may be a given heat flow, or an air temperature with a surface resistance. Temperatures and heat flows may vary in time by one of the following functions: sinusoidal, stepwise constant or linear (data may be imported/exported from/to programs such as Excel). Several other formats with climatic data can be imported.
  • Available modifications: heat sources/sinks, internal boundaries of prescribed temperature, internal regions containing air or fluid of a single temperature, internal resistances. Radiation inside cavities makes it e.g. possible to simulate a room or a crawl-space ventilated with an outdoor temperature that varies sinusoidally. The maximum number of areas with internal modifications is 100 (one application is analysis of floor heating with many pipes).
  • Conductances and capacities may be written to file.
  • Temperature field may be written to file and can easily be imported into other programs such as Matlab.
  • Temperatures, heat flows, and numerical cell indices may be presented at arbitrarily chosen coordinates (x, y).
Screen Shots


heat transfer, 2D, dynamic, simulation


The program is validated against the standard EN ISO 10211 and EN ISO 10077-2. See http://www.buildingphysics.com/index-filer/ISOValidation.htm.

Expertise Required

High level of computer literacy not required; engineering background helpful for analysis


Over 1000 in more than 25 countries (about half of them are within universities and research institutes).


Mechanical, energy, and architectural engineers working for architect/engineer firms, consulting firms, universities and research laboratories.


The integrated pre-processor is a CAD-like drawing program that makes it simple to generate input for a wide range of heat transfer problems. The geometry is built using rectangles of different materials that may overlap each other. The geometry and mesh are automatically generated. Boundary conditions are specified before solving the problem.

The following editing features are available: zoom, fit in window, select, select all of a current material, move, bring to front, send to back, import image file (EMF, WMF, BMP, ICO), import objects from other data files, add reference points.


There are extensive graphical capabilities: figures showing geometry, materials, numerical mesh, boundary conditions, 2D and 3D temperature and heat flow fields and isotherms may be displayed. Features: zoom, panning, rotation, color/gray-scale, high-resolution printing. Heat flows and temperatures can be recorded and shown during the simulation. Drawing of heat flow magnitude in color or in black and white. Images of heat flows make it simpler to determine thermal bridges and to improve designs by optimizing the insulation at areas with large heat flows. Arrays indicating magnitude and direction of heat flow may be drawn.

A "recorder" may save at specified intervals (transient or steady-state) temperatures and heat flows at given points, heat flow through boundary segments, heat flows through internal modification areas, and through internal lines.

Computer Platform

Standard PC running Windows 95/98/NT or compatible. A PC with a Pentium processor and 32 MB RAM is recommended.

Programming Language



Robust, fast and easy to use. Well-documented and well-tested program. The time to generate the complete input for a reasonably complicated case is less than 10 minutes after a few hours' experience of the program. Large problems with 60,000 numerical cells may be solved.


Cartesian coordinates must be used (sloped boundaries are modeled using 'steps').




Iliongraenden 159
Lund S-224 72


+46 (46) 136264






Software price is about $520. Free support is given via email for one year. Multiple licenses and school licenses available at lower cost. See web site for on-line manuals (PDF) and demo programs.