Investigation of the localized discomfort due to vertical radiant asymmetry in a test room with radiant and mechanical ventilation systems

The indoor environmental conditions play a crucial role in the general well-being and performance of building occupants. As people nowadays spend an increasing amount of time indoors, the investigation of thermo-hygrometric comfort has become extremely relevant. Numerous studies have explored this issue, examining both on a general and localized level. The aim of this work is to specifically investigate localized discomfort while ensuring that general comfort is maintained. To achieve this condition a series of experiments was conducted in a test room, where the variation every 90 min of ceiling water supply temperatures (30 °C, 35 °C, 40 °C) created a vertical radiant asymmetry with the floor, whose temperature was maintained at a constant temperature (18 °C). The novelty of this work consists of the realistic room and HVAC settings, that represents a typical everyday environment, where thermal conditions change dynamically. A balance between air and radiant temperatures was necessary to achieve a neutral PMV, ensuring global thermal comfort while isolating localized discomfort. The 39 involved participants provided feedback on warm and cold sensations in specific body regions through structured questionnaires. Results reveal a clear progression of discomfort: warm sensations predominated in the upper body during initial phases, while cold sensations intensified in the lower extremities as air supply temperatures decreased.