Combined effect of two local discomfort parameters studied with a thermal manikin and human subjects

Nowadays designers have to create energy efficient systems. Besides, they have to provide thermally comfortable environments for occupants. These, sometimes conflicting requirements lead to the development of such systems like surface heating and cooling systems that affect occupant's heat exchange with his surroundings via radiation. With regards to the above described systems, combined effect of two local discomfort parameters is studied in this paper, namely radiant temperature asymmetry and warm floors. The European standard CR 1752 deals with these parameters separately and no data are available on how many people are dissatisfied due to combined exposures. The paper summarizes the results of climate chamber experiments conducted with a thermal manikin as well as human subjects that were exposed to cold wall and warm floor simultaneously present. The results show that equivalent homogenous temperature (EHT) of the manikin decreased by 2 °C at the hands and face due to the cold radiating surface regardless of the warm floor. It was found that the thermal sensation and skin temperatures of human subjects were affected more by the radiation from the vertical cold surface than by the warm floor. Furthermore, genders showed significant differences regarding skin temperature change during sessions.

► As the effect of a cold surface the EHT of bare body parts decreases by 1–2 °C.
► Thermal sensation and skin temperatures were affected more by the cold.
► Genders showed significant differences of skin temperature change during sessions.