thermal building simulation

Home Products CAPSOL examples

Graphic 3D model for input and output (CAPSOL v5)

Geometric building model
  • Graphic editor for 3D drawing of walls, represented with flat faces
  • Paint tool to attribute wall types (i.e. wall compositions consisting of different layers) and zones
  • Building environment with neighbouring buildings and shading obstacles also represented with faces
  • Internal zones can have either convection and radiation (based on view factors), or global surface heat transfer.
  • Ventilation heat flows through different zones
Wall type editor
  • Material layers and cavities with thermal properties (thermal resistance, heat capacity) and radiation properties (emissivity, reflectivity, transmissivity, absorptivity)
  • Angular dependent reflectivity for exterior layer surface
  • Thermal transmittance (U-value) and total solar energy transmittance (solar factor)


Boundary conditions
  • Climate data (with e.g. hourly values): temperature, global and diffuse solar radiation on a horizontal surface
  • Geographic location and building orientation
  • Heat gains from internal heat sources
  • Comfort requirements (set-point temperatures and ventilation rates)


  • Heating or cooling based on exponential power release (with given time constant)
  • Ventilation controls
  • Sunshade controls
  • Cranck-Nicolson finite difference method to calculate temperatures every time step during a chosen period
  • Heat transfer and heat storage within wall layers are calculated one-dimensional
  • Radiation between wall surfaces are calculated using view factors (derived from 3D model)
  • A solar processor calculates the sun position and solar radiation on the different external walls, and internal solar loads through windows
  • The solar loads are calculated accurately based on the 3D building model for the direct and diffuse component, and finally attributed per wall surface to a single surface node (i.e. with averaged surface load)
  • Interactive calculation step by step is possible with ad hoc adjustment of controls
  • Calculation validated for ISO 13792, EN 15255, EN 15265
  • Graphic output filled on 3D geometry
  • Charts of node temperatures, operative temperatures, heat fluxes and powers
  • Energy analysis: conduction, convection, radiation, ventilation
  • Energy needs for space heating and cooling
  • Optimization of energy demand for heating and cooling
  • Contribution of passive solar gains
  • Use of building inertia for heat accumulation (e.g. with intermittent heating or cooling)
  • Temperature transgressions and overheating
  • Response time of heating and cooling on thermal comfort
  • Same function definitions as in VOLTRA
  • 3D solar processor in VOLTRA
Upgrade info