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In this paper a computational model developed with the objective of simulating the thermal behaviour of the passengers' compartment of vehicles is presented. The model is based on the space-integral energy balance equations for the air inside the compartment and for the main vehicle bodies and surfaces. It can solve two kinds of problems. In the first one, calculates the heat stress that the air conditioning or heating system must equilibrate, in order to satisfy predefined permanent regimen project specifications. In the second one, once imposed a particular air conditioning system and given the ambient conditions, it computes the different temperatures and heat fluxes either in transient or steady regimens. The validation of this model was done with a railway car, in a summer situation, when it was immobilized and running. The model reproduced well the experimentally determined temperature and heat fluxes evolutions.

In this paper the first results of a project, initiated in the University of Coimbra and dealing with the conjugated influence of multiple stressors in riding passengers, are presented. A field study was conducted in public transportation buses, in which the subjective response of the occupants was collected and the physical parameters related to thermal comfort, air quality, vibration and noise were acquired. More than 250 responses to a subjective inquire were collected. Besides questioning the occupants about how they felt the different stressors, the questionnaires also have a final question related to how they felt the global comfort of the vehicle, in a five-point scale. Even if it looks too far, the final goal of this project is to obtain an general comfort index that takes into account the influence of multiple stressors, thus giving to vehicle manufacturers a tool to evaluate the performance of their models and to improve the vehicle friendliness to passengers.