THE EFFECT OF FALSE CEILINGS ON THE PERFORMANCE OF PASSIVE CHILLED BEAMS

Sweden is a country with a severe winter climate. Nevertheless, cooling during working hours is oftenrequired all year around in offices. Frequently passive chilled beams are used for providing additionalcooling. Often the chilled beams are installed above a false ceiling and thereby the room issubdivided into two compartments. From the chilled beam a plume is generated. Mock up air (returnair) is required to flow into the upper compartment to substitute the airflow generated by the chilledbeam. Therefore purpose provided openings are installed in the false ceiling. The openings constitute aresistance to the flow and the locations of the openings affect the flow pattern. The overall performancewas studied in a mock up of a real office and it was found that the cooling capacity was affected by thesize and location to the openings. To achieve efficient cooling two conditions shall be fulfilled:a) The return opening area shall at least be equal to the horizontal area of the chilled beamb) The return air openings shall be located at the perimeter of the room.