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Hygric and Thermal Simulation

Designing a 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.


Material view of the indoor pool window frame with heating cables

To solve these tasks best three double core heating cables will be installed inside different chambers of the aluminium frame. The external and internal climate conditions were set according to the anticipated values including a safety margin. Based on the internal conditions of 30°C/65% RH the HTflux climate calculator tool was used to calculate a dew point temperature of 22.7°C.

Now the HTflux heat-source feature can be used to simply define the thermal loads for the heating cables. In the example given a load of 30 watts for each of the three heating cables turned out to be sufficient to prevent condensation as well as freezing in the area of the aluminium frame.

window frame indoor pool freezing condensation

Thermal simulation of the indoor pool window frame with heating cables (hatched area is below freezing temperature)

heat flux window frame

Heat flux view of the window frame area showing thermal bridging and the effect of the heating

If required, a lot of further investigation could be done using the HTflux measurements tools,
such as:

  • getting the maximum and minimum temperature of certain materials.
  • determining the response time of the heating using the transient feature.
  • creating a detailed function of the required heating power based on the external temperature.
  • measuring the portion of heating power leaving to the exterior side.
  • optimizing the heat loss to the exterior side.

Special thanks to rosenfelder & höfler, consulting engineers for providing this excellent example.