HTflux Logo


Hygric and Thermal Simulation


A paper of the Graz University of Technology dealing with concrete core activation is now available on the HTflux website. The article summarizes the main findings of the study carried out in the scope of the diploma thesis of Wolfgang Gappmaier. (more…)


Everything you always wanted to know about your heating system…

In the following example two underfloor heating systems are simulated using the dynamic simulation feature of HTflux. Based on these transient simulations we will reveal the differences in the dynamic behavior between these two systems. (more…)

Freezing Soil Frost Heave Foundation

Appropriate for the season and the current cold weather conditions in Europe a new feature has been integrated in to HTflux. The new feature will be available in next version of HTflux (1.10) which will be rolled out soon. It allows the simulation of freezing soil considering latency heat while freezing, as well as the change in thermal conductivity and heat capacity of the frozen ground. (more…)


The following practical example demonstrates how HTflux can be used to efficiently analyze even complex details with little effort. The details shows the connection of a PVC window to a timber frame wall. A comprehensive assessment regarding the condensation risk of the detail can easily be performed using HTflux unique Glaser-2d function. (more…)

window-frame heating

The following example demonstrates the possibilities of using the HTflux heat source feature. The task was to optimize a window frame heating for an indoor pool area. The aim of the heating cable design was firstly to avoid condensation at the floor section of the sliding door frame and secondly to prevent damage of the frame caused by freezing. (more…)

Transient Thermal Simulation with HTflux

HTflux latest feature enables you to process transient thermal simulations. Using the built-in video encoder you can easily create high-resolution videos of the temperature as well as of the heat-flux view or you can export the time-resolved data of the measuring tools (such as temperatures, total heat flux,…) for further analysis. This enables you to calculate dynamic thermal characteristics of your assembly (e.g. periodic thermal transmittance, time shifts, decrement factor,…)


PV Erdkabel Simulation

The video shows a simulation of underground cable array exposed to a cyclic daily clear sky photovoltaic load (maximum PV-load). The boundary conditions have been chosen to largely comply with the relevant standard VDE 0276 (20°C surface temperature, adiabatic boundaries below surface). (more…)


HTflux is highly suitable for designing, optimizing or assessing timber constructions.  The design of timber constructions can be very demanding from a hydrothermal point of view. HTflux will give you the information you need for this task.  It provides precious information for passive house planners, but it’s ease of use make it suitable for the whole construction industry. As an example we present a pitched roof junction detail of a timber frame construction. (more…)

Temperature view - underfloor heating simulation

The following example demonstrates the thermal simulation of a warm water underfloor heating system. The task is to examine the temperature- as well as the energy-distribution resulting from the underfloor heating in an internal floor with wall connection. (more…)

Balcony without thermal separation-thermal bridging

A balcony was formed by a cantilevering concrete slab. Since there is no thermal separation this poses a significant thermal bridging issue. Apart from the high energy consumption this can also cause condensation and eventually mold formation due to the low surface temperature on the inside. (more…)

Thermal Bridging - Heat Flux - Detail view

The following example demonstrates how easily and efficiently HTflux can be used to calculate the energy loss of a thermal bridge. After importing the CAD data in DXF format (e.g. created with AutoCAD or ArchiCAD) you can assign the materials with few mouse clicks.  If you have created an import wizard you can even skip this point, as HTflux will assign the materials according to the names of your CAD layers. (more…)

Flank diffusion around a vapor barrier - vapor stream density

In the present example the combination of flanking diffusion and a disadvantageous roof structure are being examined. The term flank diffusion is used to describe a process when water vapor bypasses a vapor barrier through penetrating into components that disrupt the barrier (e.g. internal walls). (more…)

Thermal bridge simulation - unresolved - heat flux

The following example demonstrates the simulation of a classical thermal bridge. The plan shows a wooden construction forming an overhanging roof parapet. In the first plan a lateral thermal insulation of the ceiling was not included. Using HTflux it can easily be shown that this setup would lead to a massive thermal bridge. (more…)