VOLTRA - Previous versions

Previous versions

Version 8

VOLTRA v8.1.02

  • Increased drawing speed in Graphic Output (new line draw algorithm).
  • Replace Help > How To's with link to website's Knowledge Base (which contains more information).
  • Retile windows every time the main application window size changes.
  • Improved navigation of tables in windows:
    • Mousewheel scroll.
    • Tab and arrow keys to move to adjacent table cells.
    • Column and row header of active cell highlighted with changed background color instead of bold font.
  • Bugfixes:
    • Avoid accidental very small zoom windows on left mouse click.
    • Avoid crash when opening Graphic Output after editing colour without closing edit with <Enter>.
    • OpenGL 3D visualisation crashes on Intel integrated GPU solved.
    • Automatically switch Tmin and Tmax in Temperature Range dialog box if Tmin>Tmax.
    • Tooltip uses correct font in table headers.
    • Allow double clicking to edit when the cell is too small to show all contents.

VOLTRA v8.1.01

  • Bugfixes:
    • Numerical error in solar processor for very small values of radiation corrected.
    • EQUIMAT always assigned solar reflection factor of 0 and solar transmission factor of 1.
  • Automatic selection of high-performance GPU (AMD or Nvidia) if present to ensure high quality 3D visualisation.
  • Off line activation of software licence keys added.
  • Cloud-based licences automatically activated when opening application.


  • Feature 'Unlimited nodes' replaces old 64-bit version
  • Documentation accessible from the VOLTRA menu ‘Help’: Manual, How to’s and Tutorials.
  • More documentation (example projects, validation projects and training material) available via the online Physibel Portal (www.physibel.be/en/knowledge)
  • Extended software protection options:
    • Hardware licence key (USB): stand-alone
    • Software licence key: stand-alone, network floating and cloud-based floating.


  • Functions compatible with TRISCO v14.0w: recalculation of blocks (Blocks > Arrange Blocks); clip blocks (Blocks > Reduce to Clip); detect void space (Blocks > Convert Void to Blocks); show materials as transparent blocks (Image > Show Transparent), display grid unit; simulation of adiabatic surface of transparent material (type TRANSMAT), graphic output of single isothermal line.
  • Show north direction and sun paths (function Image > Show North from main menu) and sun position (function View > Sun Position from graphic output window).
  • Controls which allow to replace boundary condition functions (temperature, heat power, heat flux, heat transfer coefficient, ventilation) or material property functions (thermal conductivity, infrared emissivity, solar reflection factor, solar transmission factor) with other functions (of the same type), dependent on the temperature in a sensor node compared to a temperature target function (of time) and desired heating or cooling.
    The replacement of a ventilation function can also be dependent on a minimum required temperature difference between two ventilation zones.
  • Control functions can also refer to constant functions.
    The constant function is reintroduced as function type in the Functions window.
  • The infrared emissivity of a material surface and the solar transmission factor of a material can be a function of time (intended for use with controls, e.g. for the simulation of solar screens).

Version 7.0w

  • Default data file Voltra.vtr with initialisation values for thermal properties per colour.
  • Time dependent functions for thermal conductivity, total surface heat transfer coefficient and convective heat transfer coefficient.
  • Functions compatible with TRISCO v12.0w: automatic split for grid refinement;
    equivalent thermal conductivities for cavities with different surface emissivities.
  • Show temperature or heat flux under the cursor in the graphic output.
  • 3D visualisation of sun position at any time step.
  • Show temperature profile along a grid line at any time step.

Version 6.2w

  • Diffuse solar reflection also possible in solar zone (of type BC_SKY).
  • Sun obstacles (as in CAPSOL and BISTRA), defined as sky hemisphere regions, which block direct solar radiation and decrease diffuse solar irradiation.
  • Import BISTRA data.

Version 6.1w

  • Solar processor adapted to use of 2D geometries (SECTRA).
  • Adjust coordinates of output nodes and output blocks after any grid operation.

Version 6.0w

  • Contains 3D solar processor

  • Same solar radiation climate data files as in CAPSOL (global and diffuse radiation on a horizontal surface).

  • Input required of north orientation.

  • Calculation of sun position and visualization of shadows cast by direct sun light.
    Creation of AVI animation file of shadows over calculation period.

  • Additional material properties required: reflection factor (may be a function of the angle of incidence), transmission factor (to indicate a transparent material).

  • Calculation and visualization of absorbed solar fluxes on material surfaces due to solar radiation.
    Direct solar radiation on an exterior material surface depends on geographical location, solar radiation climate data, day of year, clock time, surface orientation.
    Diffuse solar radiation on an exterior material surface depends on the view factor to the open sky and is calculated using Muneer's radiation model (also used in CAPSOL).
    Reflected radiation (of direct and diffuse incident radiation) at an exterior material surface is lost (as in CAPSOL).  An input parameter (ground reflection factor) allows to take into account the reflected radiation from the environment.
    Radiation on transparent materials are transmitted to internal zones.
    Direct radiation is projected on internal walls following the solar rays.
    Diffuse radiation is distributed on all internal walls proportional to the view factors.
    All reflected radiation at an interior material surface is diffuse and is redistributed to the other interior surfaces proportional to the view factors.
    The scheme of successive internal reflections and transmissions is solved using a radiosity method.
    The view factors can be obtained from a prior view factor calculation using a coarser grid (to speed up the processing time and reduce the required memory space).
    The absorbed solar fluxes can be output to an AVI animation file or output to a text file.

  • The absorbed solar fluxes can be used as boundary conditions for a thermal simulation (calculation of temperatures).  In this way solar heat gains on the thermal behaviour of a construction can be studied.

  • The format of view factor file is modified.

Version 6.3w

  • Improved more stable calculation of systems with ventilation flows.