Ammonia (NH3) is a crucial chemical as fertilizer and energy carrier, which is mainly produced by traditional Haber-Bosch processing that consume hydrogen and emission carbon dioxide. Electrochemical nitrogen reduction reaction...

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Radiant heating and cooling systems inherently exhibit radiant asymmetries. Although many researchers have investigated the thermal comfort effects of asymmetric radiant environments, the exposure duration has not been emphasized, especially under floor heating and cooling scenarios. In this study, we conducted a series of tests in a climate chamber with floor cooling radiant asymmetries with human participants to investigate their thermal comfort effects from short-term (2 h) and long-term (8 h) exposure perspectives. The 2 h exposure test indicates that the floor cooling systems cause discomfort complaints more easily than other radiant systems such as ceiling heating/cooling because of its stronger cooling effects on the lower body parts. The cold floor resulted in significantly colder local thermal sensations and lower local skin temperatures in the foot, calf, and thigh areas. The comparison between the 2 h and 8 h exposures suggests that exposure duration affects both the subjective and physiological thermal comfort responses significantly. Further, 2.5~4 hours are required for the foot and calf temperatures to stabilize in radiant floor cooling asymmetry cases. In accordance with these laboratory tests, we proposed two radiant asymmetry-satisfaction curves and equations for the floor cooling system with consideration of exposure duration. The calculated temperature limits for typical floor cooling room are >18.5 o C at a 2 h exposure and >20.5 o C at an 8 h exposure. These curves and temperature limits can serve as a reference for future guidelines for floor cooling system design and operation. KEYWORDSradiant systems; radiant heating and cooling; asymmetric radiation; exposure duration NOMENCLATURE BMI body mass index PD percentage of dissatisfaction Ref. reference case SD standard deviation TCV thermal comfort vote TSV thermal sensation vote Tsk skin temperature ( o C) Energy and Buildings, April 2019, 188-189, 98-110 2 https://doi.org/10.1016/j.enbuild.2019.02.009 https://escholarship.org/uc/item/8h49f5vr VRT vector radiant temperature ( o C) Δtpr radiant temperature asymmetry ( o C)

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