It is known that the internal thermal microenvironments on poultry transport vehicles vary widely between journeys and according to position within the load on individual journeys. These variations are a consequence of the external climate, transport practices including stocking density, vehicle and container design and thus load ventilation. Studies have focused on the analysis of the aerodynamic properties of commercial poultry transport vehicles and relating the findings to ‘on–board’ thermal environments and their distribution and control. It has been possible to validate the use of 1/8th scale vehicle models in a wind tunnel to characterize the external air pressure and flow patterns driving ventilation of the bird containers. Supported by computational fluid dynamic analyses these techniques have facilitated the prediction of the effects of changes in vehicle structure and transport practices upon internal ventilation and thermal loads and therefore degree of physiological stress to which birds are exposed during transportation. The findings will form the basis of recommendations for improvements in vehicle and container design in order to optimize the poultry transport thermal environment.