About the Use of Radiant Ceiling Simulation Models as Commissioning Tools

This study focuses on the experimental and theoretical analyses of radiant ceiling performance and on the use of their simulation models as commissioning tools. A steady state model of such system appears to be an appropriate tool for preliminary calculation, design and diagnosis in commissioning processes. Therefore, the main objective is to support a Functional Performance Test of the system in order to verify the radiant ceiling performance in cooling and/or heating modes. A series of experimental results obtained for seven types of cooling ceilings are used in order to validate this model.A dynamic model is also proposed to interpret the interactions of the radiant ceiling system with its environment (walls, facade, internal loads and ventilation system). This dynamic model is used to support a global commissioning procedure, to verify the radiant ceiling behavior and to evaluate the comfort conditions of the occupants. In this modeling the resultant temperature is calculated as a comfort indicator, as it depends strongly on the transient variation of the surface temperatures in the room. Dynamic tests in heating and cooling mode are used to validate the model.As an example of model application, the cooling ceiling system of a commercial building in Brussels is experimentally evaluated. Commissioning test results show that the influence of surfaces temperatures inside the room, especially the facade and ventilation are significant and that the radiant ceiling system must be evaluated together with its designed environment and not as a separate HVAC equipment.