DAVID-32 calculates temperatures and heat flows in 2- and 3-dimensional thermal bridges. The program divides the thermal bridge into small rectangular cells. The temperature in every cell is calculated (two models are used, giving an upper and a lower limit) so that the same amount of heat is entering and leaving the cell. From start, all temperatures are zero, but new temperatures are calculated over and over again until heat balance is obtained in all cells. The text is in Swedish or English. Screen Shots
Thermal bridges, temperatures, heat flows, computer program, freeware
DAVID-32 conforms to all 4 cases of ISO 10211:2007, Annex A, for three-dimensional calculation programs. The test cases are available on http://www.gadbyggnadsfysik.se
Common knowledge of thermal transfer, thermal conductivities, and boundary conditions is required. Knowledge of the international standard ISO 10211 is recommended.
The program has users mainly in Sweden, but also in England, Finland, and Germany. The number of users is unknown.
DAVID-32 is directed to researchers, architects, and building consultants.
Input can be done from scratch or by modifying a saved case. First, up to 14 materials are specified by their λ-values and up to 8 boundary conditions are given. For materials and boundary conditions there are data bases, which can be modified by the users. After that, all input data are given in graphs. Measurements are specified. Layers can be deleted and duplicated. The material number and the boundary condition number are given by clicking in the graphs.
The results can be presented in different ways, like 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 can be calculated from comparisons with reference case(s) without thermal bridge. Formulas for Ψ-values can be obtained by random variation of chosen parameters and a following regression analysis, all included in the program.
PC computers with Microsoft XP and earlier.
Quick Basic 4.
The main advantage with the program is that the result is nearly correct one also when then number of cells is very low. Compared to other programs, the number of cells can be up to 1,000 times less for the same obtained precision. The program uses the mean value of two models, one giving the upper limit and the other the lower limit of the total heat flow, see figure. Therefore the mean value will always give a good and quality secured result, where the maximum error is known.
There is no output report. The screen or any part of the screen can be copied to a BMP file.
The program can be downloaded free of charge from http://www.gadbyggnadsfysik.se.