15th ROOMVENT Conference-ConfTool Pro Export

Requirements for room thermal environment and air quality are specified in the present standards. Indoor air quality is expressed as the required level of ventilation or CO2 concentrations. Mass balanced method and method based on person and building component are used for determination of the supplied airflow rate (CEN CR 1752, DS/EN15251). Room thermal environment can be achieved by use of combined (convective and radiant) or only convective systems. In this study we compared the room thermal environment obtained with the two methods for determination of the ventilation rate and two systems, combined system and convective system alone. Physical measurements were performed in a simulated meeting room with eight occupants: seven persons and one thermal manikin. Heated window was used to imitate solar load. The ventilation air was supplied from ceiling slot diffusers. Based on the mass balanced method CO2 concentration of 1000 ppm at the exhaust was obtained with supply flow rate of 57.4 L/s. CO2 concentration of 1000 ppm was also obtained when the supply flow rate of 68.1 L/s was calculated based on the method of person and building component (category B of DS/EN15251). The supply air temperature and the chilled ceiling temperature were adjusted to maintain room temperature of 26 °C. Room temperature of 26 °C was also maintained at air supply flow rate of 142 L/s without use of the chilled ceiling. The results reveal that most uniform thermal environment in the occupied zone was achieved at 68.1 L/s and best mixing (i.e. best air quality) was achieved at 142 L/s. The draught discomfort was lowest at 54.7 L/s. The thermal manikin measurements revealed better overall thermal comfort at 68.1 L/s. These results, together with consideration on cost and complexity of the used system as well as energy use, may help ventilation design.