UMIDUS logo.

Models coupled heat and moisture transfer within porous media, in order to analyze hygrothemal performance of building elements when subjected to any kind of climate conditions. Both diffusion and capillary regimes are taken into account that is the transfer of water in the vapor and liquid phases through the material can be analyzed. The model predicts moisture and temperature profiles within multi-layer walls and low-slope roofs for any time step and calculates heat and mass transfer. Umidus has been built in an OOP language to be fast and precise easy-to-use software.

Umidus is especially useful for studies of hygrothermal behaviours of building envelope and roofs. Users can quickly build different construction elements and compare them in terms of heat flux, mass flow and moisture content and temperatures profiles. Reports of building parameters and graphs of results can be effortlessly exhibited.


moisture calculation, latent and sensible conduction loads, heat and mass transfer through building envelopes



Expertise Required

Some experience with Windows programs is important. Familiarity with heat and mass transfer is desirable but not absolutely necessary.


10 -- just released in late 1999.


: Building researchers (Physicists, Mechanical Engineers, Civil Engineers, Architects etc.) and Moisture, energy consultants and students of engineering and architecture.


Building element description (thickness, layers, azimuth, tilt etc.), weather data, hygrothermal properties (including vapor and liquid transport coefficients). Details of the construction of the element to be simulated are entered in the Construction Element window. Each layer of the element is entered as a row in a table. The element can have a maximum of 10 layers. The user defines the material of each layer from the pull-down menu. There is a choice of 20 materials.


The user chooses desired output options in the Report Options window. Umidus generates profiles of temperature, moisture content, and fluxes of heat and mass through the building element. The time period for which the results are required are entered by the user. The simulation results are presented in the form of 6 graphs.

Computer Platform

PC-compatible, 386 or higher; Windows 95, 98 and NT operating systems

Programming Language



No limitations such as low moisture content and high computer run time. It possesses a robust generic tridiagonal-matrix solution algorithm that solves the temperature and moisture content distributions simultaneously at each time step that makes it more precise and numerically stable. It allows calculation of sensible and latent heat transfer through building elements. Higher accuracy in the heat transfer calculation and the associated thermal loads calculation is achieved by allowing the basic thermal properties of the wall material to depend on moisture content. A very useful feature of Umidus is the visualisation of the properties of the materials. In the Visualise Material window, the mass transport coefficients, conductivities and sorption isotherms of up to 8 materials can be plotted as a function of moisture content. The next step is to implement calculus routines, that allow evaluation of all heat and mass transport coefficients from basic data such as pore size distribution, sorption isotherm and dry-basis thermal conductivity.


Umidus does not simulate 2-D or 3-D phenomena.



Pontifical Catholic University of Parana


(PUCPR/CCET) Thermal Systems Laboratory
Rua Imaculada Concei��o, 1155
Curitiba, PR 80-215-901


+55 (41) 330-1322


+55 (41) 330-1620




Available 'as is' at no-charge. The PC executable version can be downloaded from the web site of the Thermal Systems Laboratory at Pontifical Catholic University of Parana.