Artesis Hogeschool Antwerpen

Heat loss of the human head under bicycle helmets, for designing safer bicycle helmets

Op maandag 28 juni 2010 had aan de Faculteit Bio-ingenieurswetenschappen in de Campusbibliotheek Arenberg te Heverlee de publieke verdediging plaats van het doctoraat van Guido De Bruyne.
'Heat loss of the human head under bicycle helmets, for designing safer bicycle helmets.'
Cycling is very popular, especially in Flanders. It is healthy and environmentally friendly. Unfortunately, about eight times more cycling fatalities occur compared to car fatalities per travelled kilometre. Head injuries are the most frequent cause of death in about 69% of the cycling fatalities. Current bicycle helmets reduce approximately 60% of severe head injuries in cycling fatalities. Unfortunately, bicycle helmets are not always popular. In Belgium, less than 5% of the cyclists wear one. Cyclists refuse to wear bicycle helmets due to peer pressure, lack of style of the current bicycle helmets and discomfort, especially thermal discomfort. This dissertation investigated if it was possible to improve the micro-climate in the volume between a head and a bicycle helmet if experimental setups and mathematical models are developed that allow studying the effect of bicycle helmets on the local micro-climate of a head.
In this dissertation it was shown that the air temperature in the space between head and bicycle helmet increases with approximately 3°C at 20°C from the front of the head towards the rear and that sweat production on a head under a bicycle helmet was on average 30% to 50% higher at the rear of the head, compared with the front for low and moderately high work rate. Using object studies, it was shown that only a fraction of the fresh air in front of a bicycle helmet enters it. At best, only 17% to 18% of the fresh air 50 cm in front of a bicycle helmet reaches the front of the head when people are cycling at low speed (3 m/s). Fresh air concentration at the rear of the head can even diminish to 1% compared to the fresh air concentration in front of a bicycle helmet. These results were unexpected, but were confirmed using a mechanistic model (CFD). The studies showed that there is a large potential for improving the ventilation efficiency of bicycle helmets. As a result, a new kind of bicycle helmet concept is proposed with on average 16% more ventilation efficiency, while having three times less vents compared with the helmet it was optimized from. Finally, first steps are taken towards an active ventilated bicycle helmet that may allow designing helmets with even fewer vents.


Guido De Bruyne
Licentiaat in productontwikkeling, Hogeschool Antwerpen
Ingenieur (ir.) Industrieel Ontwerpen, Technische Universiteit Delft
Doctor in de Bio-ingenieurswetenschappen, Katholieke Universiteit Leuven