Previous versions

Version 4

BISTRA v4.2.01

  • Bugfixes:
    • Automatically switch Tmin and Tmax in Temperature Range dialog box if Tmin>Tmax.
    • Template file Bistra.bst not always correctly read on program start-up.


  • Possibility to assign a fixed sun position (solar radiation perpendicular to bitmap border) as an alternative to a real sun path
  • Improved algorithm for visualizing BC_FREE in graphic output resulting in higher rendering speed
  • Off line activation of software licence keys added
  • Cloud-based licences are automatically activated when opening the application
  • Bugfixes:
    • EQUIMAT always assigned solar reflection factor 0 and solar transmission factor 1


  • Feature 'Unlimited nodes' replaces old 64-bit version
  • Documentation accessible from the BISTRA menu ‘Help’: Manual, How to’s and Tutorials.
  • More documentation (example projects, validation projects and training material) available via the online Physibel Portal (
  • Extended software protection options:
    • Hardware licence key (USB): stand-alone
    • Software licence key: stand-alone, network floating and cloud-based floating.
  • Bugfixes:
    • Numerical error in solar processor for very small values corrected


  • Functions harmonised with BISCO v11.0w: write compressed BMP files; equivalent thermal conductivities (EQUIMAT, TRANSMAT) and convective surface heat transfer coefficients (BC_FREE, BC_SKY, BC_NOSKY) dependent on dominant heat flow direction derived from temperature field (rules CEN_DIR_I, CEN_DIR_E); definition of cavity emissivities; improved radiation simulation in a TRANSMAT cavity at the bitmap border; graphic output of single isothermal line; fill bitmap in graphic output.

  • More clear visualisation of sun path of current day and current sun position (visible or hidden by sun obstacles) above horizontal plane.

Version 3.0w

  • Default data file Bistra.bst with initialisation values for thermal properties per colour.
  • Time dependent functions for thermal conductivity, total surface heat transfer coefficient and convective heat transfer coefficient.
  • Simulation of ventilation flows through different zones following user-defined ventilation paths.  The ventilation volume flow rates refer to time dependent functions.
Presentation BISTRA v3

Version 2.0w

  • Solar processor based on direct and diffuse solar radiation climate files.
    Solar irradiation on (slanted) edges of triangulated object geometry.
    Solar reflection factor based on angle of incidence.
    Solar transmission factor after subtraction of reflection.
  • Definition of north orientation based on 3 rotation angles around 3D rotation axes.
  • Sun obstacles as spherical rectangles on the sky hemiphere (defined by azimuth and altitude coordinates).
  • Sun path visualisation (in animation video).
  • Diffuse solar radiation redistributed using radiosity method.
  • Output of absorbed solar fluxes.