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  • According to EN calculating the

    2018-11-12

    According to EN 15255 (2007), calculating the dynamic cooling load requires that surface temperatures be calculated according to EN 15377-1 (2009) for surface cooling systems. The calculation is divided into four classes, and a class 4 calculation must be conducted for surface cooling systems. EN 15255 (2007) provides the basis for a simplified dynamic calculation of the cooling load.
    Building/room setup A series of measurements was conducted in an existing office building located in Vienna, Austria; this building had different façade systems. The 34th floor consists of four identical rooms with an area of approximately 10.8m2 each. The façade is a west-orientated and totally glazed surface. Given that the rooms are situated on the 34th floor, they purchase C646 are not shaded by other buildings or geographical surroundings. Figure 1 shows the floor plan of the test rooms. The rooms are adjacent to one another and are separated by a gypsum plasterboard wall. Rooms 01 and 04 are adjacent to an open-space office area, which was empty during the measurement period. The floor is a raised floor and is open throughout the entire story because of its air leading properties (i.e., the supply of air is realized over the raised floor). The floor cannot be closed; otherwise, the test rooms will not obtain fresh air. The suspended ceiling of the measurement rooms is separated by a foreclosure (mineral wool) around and between these rooms. The configuration of the test rooms is typical for a single-person office. The dimensions of the room are visualized in Figure 2(a). The left side shows the floor plan of one room, which has a room depth of 4.10m and a width of 2.6m. The right side shows the section view and marks the main heights. The room height of the occupied area of the room is 2.8m, the height of the façade area is 3.0m, and the floor height is 3.5m.
    Measurement setup A schematic overview of the measurement equipment for the rooms is shown in Figure 6. The measurement interval is 1min, and the measurement parameters are as follows: The flow and return temperatures of the cooling medium are measured by temperature sensors. The mass flow is measured by a differential pressure meter that is compatible with the mounted valves. Control measurements are conducted by an ultrasonic flow measuring meter. The measurement points for the flow and return temperature of the cooling medium and the mass flow are shown in Figure 7 (blue points). The operative temperature is measured by a globe thermometer at different depths of the room by PT1000 temperature sensors in a black ball with a diameter of 100mm, each at a height of 1.20m. A schematic overview of the measurement points is shown in Figure 7 (red points). The ambient temperature, humidity, and radiation on the west façade are measured every minute at the roof of the building. The effect of the internal loads is realized by a heat mat with a load of approximately 45W/m2 and is activated by a timer. The operating time is from 8 A.M. to 12 P.M. and from 1 P.M. to 5 P.M.
    Results
    Summary and outlook This study tested different room configurations using an intensive set of measurements to determine the effect of different façade systems on the operative temperature at the center of the room and close to the façade and the resulting cooling capacity of the cooling ceiling. The room conditions were tested by varying the following elements of the boundary conditions: The measurement results of the operative temperatures show an effect caused by the façade type. The temperature difference between the “worst case” and the “best case” scenario is 3.8K in reference to the room center (4.7K next to the façade). The results of the calculated effect on the cooling capacity show an increase of approximately 15W/m2(cooling area) because of the additional cooling element. The change from single-skin façade to single-story double-skin façade leads to an increase of approximately 30W/m2(cooling area) in the cooling capacity.