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Distribution of carbon dioxide in a naturally ventilated room with high internal heat load

: Steiger, S.; Hellwig, R.; Junker, E.

Fulltext (PDF; )

Rode, C. ; Technical University of Denmark -DTU-, Lyngby:
8th Nordic Symposium on Building Physics in the Nordic Countries 2008. Proceedings. Vol.1 : Copenhagen, June 16-18, 2008
Lyngby, 2008 (DTU Byg Report 189)
ISBN: 978-87-7877-265-7
Nordic Symposium on Building Physics in the Nordic Countries <8, 2008, Kopenhagen>
Conference Paper, Electronic Publication
Fraunhofer IBP ()

The paper shows results of measuring the carbon dioxide distribution in a test room with natural ventilation and high occupant density. The test room represented one tier of a classroom with tiltable windows on one side. Dummies emitting heat and carbon dioxide simulated the pupils. The measurements of carbon dioxide were carried out at various places and heights to see the characteristics of carbon dioxide and indoor air flow and also to find possible measuring positions for carbon dioxide sensors to control indoor air quality. The distribution of the carbon dioxide was influenced by several issues. First of all it depended on the disposal of carbon dioxide, second on the status of the window and at last on the heat emission of the dummies. With an open window and carbon dioxide emitted, the concentration of the gas varied in a wide range over the room. The highest concentrations were measured below the ceiling, the lowest above the floor, but there was not always a stable stratification. With the window closed and no carbon dioxide emitted, the concentration equaled over the room in a few minutes. When there was no thermal buoyancy at the dummies, more carbon dioxide emitted from the dummies dropped down to the floor because of its higher density. Near the window as well as below the ceiling high fluctuations of the carbon dioxide concentration appeared. The measured values near the wall were also more stable than the values in the middle of the room but comparable to them. Therefore appropriate measuring points for classrooms could be at the wall at breathing height with an adequate distance from the windows. Higher measurement points at the wall, out of the students reach, could also be possible, but may show too high values. Measurement points near the floor and near the windows are inappropriate to estimate indoor air quality.