Software for heat transfer and ground heat

HEAT3 - Heat transfer in three dimensions


HEAT3 is a PC-program for three-dimensional transient and steady-state heat transfer. The program is along with the two-dimensional version HEAT2 used by more than 1000 consultants and 100 universities and research institutes worldwide. The program is validated against the standard EN ISO 10211.  [click here for ISO 10211 validation test cases]

Examples of applications [
click here for graphical examples]

· General heat conduction problems

· Thermal bridges

· Calculation of U-values for building construction parts

· Estimation of surface temperatures (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


· Well tested and robust pc-program. Well documented with a succinct theory. Easy to learn to use. Handy and rapid input due to an integrated pre-processor.  Automatic mesh generation. Quick numerical method with optimization. Both steady-state and dynamic analysis. Multiple consecutive simulations may be started externally (batch mode).  

· Post-processor with extensive graphical capabilities in 2D and 3D of geometry, materials, numerical mesh, boundary conditions, temperature field, heat flow arrays and isotherms. Features: zooming, panning, rotation, color/gray-scale, high resolution printing. Arbitrary heat flows and temperatures can be recorded (transient calculations).  Charts can be printed and exported in different formats (text, Excel, HTML, XML, Metafile, bitmap). The Movie Maker captures graphical output data, such as temperatures, isotherms, and heat flows to an AVI-file.

· Any structure consisting of adjacent or overlapping rectangles with any combination of materials may be simulated. Up to 50 million nodes may be used (requires a PC with 3 GB RAM).

· Boundary conditions may be a given heat flow, or a temperature with a surface resistance. Temperatures may vary in time (sinusoidal, stepwise constant, stepwise linear). Several formats with climatic data such as TRNSYS, DOE, METEONORM, HELIOS, TMY2, SUNCODE, MATCH, and EXCEL can be imported for dynamic calculations

· Available modifications: heat sources/sinks, internal boundaries of prescribed temperature.

· The Report Generator produces on-the-fly a printable document with optional text and figures with project info, and input/output data.

· Automatic calculation of thermal coupling coefficients (L3D) according to EN ISO 10211 for a wide variety of problems involving thermal bridges.

· 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 für Normung, DIN V 4108-4) is also available.


Click here for current version update info

Free light version:
Click here to download a free light version  


Tips for reading for beginners: For a quick start read Chapter 4 in Manual HEAT3 4.0. The examples in Chapter 5 would also be useful. After this, look at Update manual for HEAT3 5.0 and Update manual for HEAT3 6.0. Also see [ISO 10211 validation test cases].


· Update manual for HEAT3 8 (PDF), 2017

· Update manual for HEAT3 7 (PDF), 2015

· What's new in version 6 


· Update manual for HEAT3 6 (PDF), 2011

· Update manual for HEAT3 5 (PDF), 2005

· Manual for HEAT3 4.0 (PDF), 2001


· Frequently asked questions


· Überblick

· Updatemanual für HEAT3 5 (PDF), 1.1 MB, 28 Seiten, Stand 10. Okt. 2005

· Programmbeschreibung HEAT3 4.0 (PDF), 2,7 MB, 153 Seiten




· United Kingdom: Training/certification is offered in English by Stroma.




· France: Training in French. Formation en français par

Psi Thermique 


· North America: Training is offered by




· CIS-countries, Latvia, Lithuania, and Estonia: see


· List of universities using HEAT2/HEAT3

· Theory of HEAT2/HEAT3, (Doctorate thesis, Blomberg), (PDF), 2.5 MB, 202 pages, 1996

A separate program that reads HEAT2 6+7 reports is available for free here: (600 kB)   (also contains an example of a generated report)

Older versions
These versions were written for Windows 98/XP and we do not support them anymore.

Old version 5


· What's new in version 5 


Old version 4

· Overview


· Info sheet (PDF), 130 kB


· Manual (PDF), 2.3 MB, 153 pages, revised Sept 28, 2001

· Screen video of input - (A bath tub), 1.5 MB

Old version 3 

· Manual (PDF), 1.4 MB, 95 pages, revised Feb 10, 1999