Indoor climate conditions with HVAC room unit integrated into the suspended ceiling or island ceiling

The target of the operation of the HVAC room units is to maintain good indoor climate conditions for occupants and stable supply air distribution in varying occupancy/heat load levels. In this study, meeting room cases were simulated with HVAC room units integrated into the suspended ceiling or island ceiling for analysing challenging, non-uniform heat load situations. Office room and meeting room cases with the suspended ceiling were earlier measured in full-scale test setups and modelled with CFD simulations. The simulated meeting room setup included heat loads from 10 occupants, computers, ceiling lighting and window solar heat gain. Active diffusers with radiant panels provided cool ventilation supply airflow and additional water based cooling to compensate heat gains. CFD simulations were performed in steady state conditions with RANS simulation method and with SST turbulence model. Buoyancy and thermal radiation heat transfer were modelled. A fine computational grid was used with detailed modelling of supply airflow patterns. This study revealed new understanding of locating HVAC room units in office spaces. When integrating HVAC room units into the island ceiling vertical temperature stratification on top of island ceiling was obtained. Indoor climate conditions were otherwise similar in both situations with active diffusers.