Thermal Environment in Room with Ventilation Design Based On Air Quality and Different Cooling Methods

In this study, the room thermal environment generated with a convective system was compared with the environment generated with combined convective and radiant (chilled ceiling) system. Physical measurements were performed in a full-scale meeting room occupied by seven persons and one breathing thermal manikin. Heated window and electrical foil on the floor were used to imitate solar load. Room temperature of 26 °C was maintained. Outdoor air was supplied from ceiling slot diffusers. The combined system was operated at two supply flow rates: first, 58 L/s based on CO2 mass balance to achieve 1000 ppm at the exhaust (supply air temperature of 18 °C, chilled ceiling temperature of 21.5 °C) and second, 68 L/s based on the method of person and building component (supply air temperature of 18 °C, chilled ceiling temperature of 21.3 °C; category II of EN 16798-1:2019). In the case of convective system only 127 L/s of air was supplied at 18°C. The results reveal that most uniform thermal environment in the occupied zone was achieved with combined system with ventilation rate based on number of occupants and building component and best mixing was achieved with the convective system operated alone. The combined convective and radiant system at 58 L/s lead to the lowest draught rate and highest vertical temperature gradient. These results, together with consideration on cost and complexity of the used system as well as energy use, may help ventilation design.