This paper proposed to discuss some issues about indoor microclimate parameters design in radiant cooled residential buildings. Based on the thermal comfort model, the relationships between low mean radiant temperature and other thermal microclimate parameters such as indoor air temperature, air velocity, and relative humidity were analyzed. The improved and reasonable combinations of four thermal microclimate parameters including radiant cooling surface temperature, air temperature, air velocity, and relative humidity were further derived. Furthermore, a number of new thermal comfort charts using radiant cooling surface temperature and air temperature as dominant parameters were drawn. The results show that the air temperature can be increased 1–3℃ within the recommended thermal comfort range when the mean radiant temperature is reduced 3℃. Under the design goal of thermal neutral, when the chilled ceiling surface temperature is in the range of 16–26℃, the air temperature should be set at 25.3–29.3℃; when the chilled floor surface temperature is in the range of 19–26℃, the air temperature should be set at 25.8–29.2℃. The design values of air velocity and relative humidity are not recommended to be changed, and still can follow the design standards for conventional all-air systems. Practical application: In this paper, some issues about indoor microclimate parameters design in radiant cooled buildings were discussed. A number of new thermal comfort charts using radiant cooling surface temperature and air temperature as dominant parameters were provided, and the design values of indoor air temperature, mean radiant temperature, air velocity, and relative humidity for radiant cooling system in residential buildings were also suggested. The research results can provide a more intuitive reference for the design of radiant cooling systems in residential buildings.

The performance of a residential radiant chilled ceiling system combined with an outdoor air handling unit under steady operating conditions in summer was tested, and the stable operating characteristics of this system were analyzed. Indoor thermal environment parameters of room which employed this system were measured and analyzed and the thermal comfort evaluation of occupants was given. The results show that the composite system works well in summer, which can provide low-and high-temperature chilled water for the air supply terminal and the radiant terminal devices. Good thermal comfort can be achieved in room which employed this system, and no condensation risk occurs when it is applied in hot summer and cold winter zone of China. All the analysis provides a technical support for the popularization of the residential radiant chilled ceiling system combined with an outdoor air handling unit in China, and provides a reference for the further optimization of this system.

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