An investigation of thermal comfort inside a bus during heating period within a climatic chamber

• A general and combined testing and calculation model for thermal comfort assessment of a bus HVAC design was described.
• Thermal comfort investigation inside a coach during heating period within a climatic chamber was carried out.
• Transient Energy Balance Model by Gagge et al. was used to calculate changes in thermal parameters.
• The model developed for use of HVAC engineers and scientists is valid for all vehicle types.
• Iterations to reach to the desired thermal comfort condition are possible with the given model.

By this study, it was aimed to define a testing and calculation model for thermal comfort assessment of a bus HVAC design and to compare effects of changing parameters on passenger's thermal comfort. For this purpose, a combined theoretical and experimental work during heating period inside a coach was carried out. The bus was left under 20 °C for more than 7 h within a climatic chamber and all heat sources were started at the beginning of a standard test. To investigate effects of fast transient conditions on passengers' physiology and thermal comfort, temperatures, air humidity and air velocities were measured. Human body was considered as one complete piece composed of core and skin compartments and the Transient Energy Balance Model developed by Gagge et al. in 1971 was used to calculate changes in thermal parameters between passenger bodies and bus interior environment. Depending on the given initial and environmental conditions, the graphs of passengers Thermal Sensation and Thermal Discomfort Level were found. At the end, a general mathematical model supported with a related experimental procedure was developed for the use of automotive HVAC engineers and scientists working on thermal comfort as a human dimension.