Methodology for the Evaluation of Natural Ventilation in ... - Cham

Table 20. Model Surface Characteristics by OrientationPrimaryMaterialNumber of Openings Size of Opening SurfaceAreaNorth Wall MDF 28 (2 levels of 7 per floor) 17.1 cm x 2 cmEast Wall MDF None ---South Wall MDF 28 (2 levels of 7 per floor) 12 cm x 2 cmWest Wall MDF 2 View Windows 50 cm x 120 cm10 cm x 60 cmRoof Plywood 3 (along atrium roof) 7.5 cm x 7.5 cmFloors Plywood None NoneOverallU-ValueDue to the complex geometry of the awning-type windows found in the prototype, the openingswere simplified to a vertical, rectangular cut-out in the façade. The windows were sized basedon the effective opening area defined in Chapter 3 experiments. Two sets of seven windowswere modeled for each floor level of the model; an upper vent and lower window opening. Theupper opening is located near the ceiling (24 cm from the floor to the sill), while the loweropening is located near the floor (5 cm above the floor). The locations and heights of thewindows relative to the floor remain constant for both upper and lower openings, on both sidesof the building (north and south) at all floor levels. Though the height remained the same, 2 cm,the width of the windows on the north façade is larger than those on the south façade. Thewindow in the prototype building had wider window openings on the northern façade than thesouthern façade. The windows for the scale model on the southern façade are 12 cm in widthshown in Figure 32, while those on the northern façade are 17.1 cm wide shown in Figure 31.The stack vents, used to assist ventilation in the prototype building and located along the roof ofthe atrium were created in the reduced-scale model. These three openings are located along thecenter of the roof of the atrium. Each measures 7.5 cm by 7.5 cm, and they are locatedapproximately 0.40 cm apart. These openings can be either open or closed depending on thecase being modeled. They are evenly spaced and centered across the 1.8 meters of the atrium, asshown in Figure 33.The floors within the model, including the ceilings/roofs, were constructed of a layer of 1/8thinch plywood and a layer of R-6.5 insulation board. The insulation was required to reduce heatloss to the test chamber (external environment) and heat transfer between floors. There arecolumns in the model along the atrium similar to those in the prototype building. These inchthick,dowel-rod columns allow for the unrestrictive opening between the occupied spaces andthe atrium, and provide support to the floors of the model. A combination of More-Tite® ropecaulk and duct tape was used to seal up joints within the model to reduce and control air leakagebetween floors and to the ambient.97