PARIS: A car air conditioning system works best when occupants don’t notice it.
Setting it up just right is a complex process especially when you are talking about the ones built into high performance cars, said Bugatti air-conditioning systems designer Julia Lemke.
The entire air conditioning system includes the cooling circuit for the interior, air flow, electrical system, electronics and the air conditioning unit as the system’s central control unit.
"At first glance, our air conditioning system appears to function like a conventional system. But it’s a real challenge to perfectly harmonise the highly complex system of a small-series hyper sports car so that it works impeccably even at maximum speed and engine load,” said Lemke.

Lemke conducts research and development on maximum cooling capacity as well as efficiency, system acoustics and draught reduction. This includes reducing and refining the refrigerant circuit so as to minimise the use of refrigerants and energy consumption.
Lemke designs new air conditioning systems to ensure that the air flow and air conditioning work well in the new Chiron Pur Sport, Divo and all other Chiron models.
It’s a task with considerable responsibility: two air-conditioning condensers ensure heat dissipation from the vehicle, a central air conditioning unit is responsible for control, and a compressor drives the entire system. This system is made up of air conditioning lines with a considerable length of 9.5 metres due to the mid-mounted engine concept.
One challenge when adjusting the air conditioning system is that each individual has their own individual sensation of temperature. Europeans usually feel comfortable between 21 and 22 degree Celsius, while most Americans prefer it a few degrees colder.

“For us, it’s important to ensure that the selected temperature is quickly established. But there mustn’t be any draughts."
The requirements are huge: “Our vehicles travel very fast. In order for the air supply to work properly at maximum speed too, we need to ensure the ventilation and air conditioning are particularly well controlled,” said Lemke.
For this purpose, the air conditioning system changes the air flow at fast driving speeds. In conventional vehicles, air is forced into the interior at the lower end of the windscreen, but in a Bugatti this only happens up to about 250kph.
From this point onwards, there is a switch to negative pressure: a sophisticated control system with an additional ram air flap and an optimised blower ensures that air continues to enter the interior.
The Bugatti hyper sports car also has other unique features: because of the incredible speeds reached, sometimes well over 400kph, the body is designed to be particularly streamlined.

This requires a flat windscreen with an inclination of just 21.5 degrees. This increases the surface area of the glass to 1.31 square metres – a conventional compact car has a glass area of around 0.70 square metres and an angle of inclination of around 30 degrees.
As a result, the interior of a Bugatti heats up more due to the higher solar radiation or solar load. Sky View – the glass roof option popular among Bugatti customers – further increases the level of interior heat when the sun is shining.
To counteract this, the Chiron models and the Divo have a powerful air conditioning compressor with a cooling capacity of up to 10 kW and two air conditioning condensers – enough to cool an apartment in Europe measuring 80 square metres. About 3kg of coolant per minute can be compressed from a pressure of about 2 bar to a high pressure of up to 30 bar.
In addition, the compressor mounted on the engine is exposed to very high ambient temperatures due to its proximity to the exhaust system, so this is cooled by another sophisticated system.
Lemke's mission is to continue perfecting and adjusting the air conditioning system so that the vehicle occupants feel comfortable and do not hear or feel any draughts. The job is done only if they don’t notice anything at all.