Cabin comfort in business jets - development of model-based comfort and certification approaches

Business Jet
© Fraunhofer IBP
View of the business jet cabin.

What impact does the thermal bridge at floor level in an aircraft have on thermal comfort?

How does solar radiation affect the way comfort is perceived inside the aircraft?

What happens inside the cabin if the air-conditioning system fails, and the air temperature outside is cold?

These and other questions can be studied in the business jet mock-up at the Flight Test Facility, Fraunhofer IBP's flight laboratory. Different measurements are performed to validate indoor climate models, thus enabling answers to these and other questions to be predicted in the future with the help of simulation. These simulations are particularly used in extreme thermal cases such as extreme heat or cold, where test persons cannot be used.

Project goals

The aim of the “Novel Certification” project is to map the physiological response of humans in their thermal environment with the aid of simulations. To achieve this, a simulation model for the indoor climate, a zonal model, is coupled with a model which simulates the human response to the climate. The resulting thermo-physiological model can then be used to predict whether the person is still in their comfort zone or in danger of getting too hot or too cold. This is where the DressMAN comfort measurement system comes into play. The system makes it possible to validate the exchange of energy from a person’s body with their environment.

Thus, simulation can now be used as a tool in comfort studies to find out the most efficient measures to improve comfort. For extreme thermal cases such as extreme heat or cold, a thermo-physiological model can additionally be used to predict how the core body temperature will gradually adjust. As a result, limits can be defined of what is “tolerable” if the air-conditioning system fails.

The measurements are also used to evaluate local thermal comfort in the aircraft cabin and derive improvement measures.

Current project status

The “Novel Certification” project was able to answer numerous questions on cabin comfort in business jets. For example, it was possible to demonstrate that although solar radiation through the window can warm parts of a person’s upper body, the effect is too small to cause discomfort of the whole body. Another example is the thermal bridge at floor level in an aircraft, which may cause cold feet. Heating the sidewall of the aircraft proved to be the most efficient measure against this because heat radiation enables warmth to reach the feet and lower legs.

The simulation model is currently undergoing validation and has already been coupled with a thermo-physiological model for the first time.

Project partners

  • Dassault Aviation 
Heating of Dado panels
© Fraunhofer IBP
Heating of the dado panel.
Comparison methods to mitigate the loss of comfort
© Fraunhofer IBP
Comparison methods to mitigate the loss of comfort due to cold floors, measured with DressMAN.