Modelling the thermal microenvironment of footwear subjected to forced ventilation

In this paper, we develop a mathematical model of the thermal microenvironment in footwear that considers forced ventilation of the footwear cavity. The developed model was validated using a newly developed thermal foot-manikin system and the results show that the model effectively predicts the total dry thermal insulation of footwear under various dynamic conditions. The footwear cavity model is then integrated with a thermoregulation model, and the integrated model effectively predicts changes in foot skin temperature resulting from forced ventilation (0-90 L/min). At an air temperature of 26.4 °C and a foot thermal comfort temperature of 32.2 °C, the required minimum ventilation rate was found to be 5.4-24.6 L/min, which corresponds to a total static thermal insulation of footwear of 0.10-0.20 m2·K·W-1. This indicates that ventilation can adequately control the thermal microenvironment of the footwear cavity, thereby maintaining foot thermal comfort. Practitioner summary: An adverse footwear thermal microenvironment results in foot thermal discomfort and foot hygiene problems. We hypothesise that forced ventilation may enable thermal control of footwear microenvironments. A mathematical model was developed which can determine the forced ventilation rate required in a given type of footwear to create foot thermal comfort.