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UNorm calculates U-values, temperatures, heat flows, and Ψ- or Χ-values in 2- and 3-dimensional thermal bridges. The program divides the thermal bridge into small cells. The temperature in every cell is calculated so the same amount of heat is entering and leaving the cell. At the start, all temperatures are zero, but new temperatures are calculated until heat balance is achieved in all cells.

The program uses two models, giving an upper and a lower limit for the heat flow when a thermal bridge is calculated. The result is quality secured as the maximum error and the interval for the true heat flow and for the thermal bridge value. The text is in Swedish and English. Screen Shots


U-values, thermal bridges, temperatures, heat flows, computer program, freeware


UNorm is validated and conforms to all 4 cases of ISO 10211:2007, Annex A and to all 10 cases in EN-ISO 10077-2:2003. The validation is included in the program.

Expertise Required

Common knowledge of thermal transfer, thermal conductivities, and boundary conditions is required. Knowledge of the international and national standards for U-values and thermal bridges is recommended.


The number of users is unknown.


UNorm is directed to schools, researchers, architects, and building consultants.


Input can be done from scratch or by modifying an example or a saved case. Help is shown automatically when the user points at an input parameter, and every screen page has a help button behind which the page is explained. There is also a separate help section, where answers to most questions can be found. Seven demo cases are included, where the input of data is explained in detail. A database for thermal conductivities, R-values, and emissivities is included.


The results are presented in tables (U-values) and graphs (thermal bridges). Input and output data are shown on the same screen, and the program is designed for sensibility analysis. Hence, the screens seem to be messy at first, but the user should soon see the advantage of this design. It is easy to see the effect of a change in input data. The results can be presented in different ways: temperature and heat flow graphs, isotherms and heat flow lines. The number of cells can be varied. Parts of the structure can be enlarged when graphs are presented. Ψ-values are calculated from comparisons with reference cases without the thermal bridge. Formulas for Ψ-values can be obtained by automatic variation of chosen parameters and a regression analysis.

Computer Platform

PC computers

Programming Language

Visual Basic 2010 Express Edition


The program is fast and exact. Because two models are used, the number of cells can be very small. Input and output data are seen on the same screen. Demo cases, detailed help, explanations, and a data base are included. Formulas for Ψ-values can be obtained.


There is no output report. The screen can be copied with the Print Screen button.



Gad Byggnadsfysik


Lindögatan 3, S-25731




The program can be downloaded free of charge from