在佛罗里达州中部的70座小型商业建筑中进行的现场测试表明，33座建筑的空气分配系统使用了建筑空腔。各种建筑空腔类型（括号中的建筑数量）包括:封闭式空气处理器支撑平台（10）、机械柜（8）、机械室（6）、天花板空间（7）、墙壁空腔（6）、墙槽（1）和“其他”建筑空腔（2）。测试发现，这些建筑空腔比标准管道和静压箱的泄漏性要大得多，因为它们通常没有按照与管道相同的气密性标准建造。实际的空气泄漏不仅是管道孔尺寸的函数，而且是泄漏部位压差的函数。 压差一般在-0.080英寸之间。WC（-20帕）至-0.401英寸。支撑平台、机械壁橱和房间、墙壁空腔和墙槽中的WC（-100 Pa）。相比之下，天花板静压箱通常在小于0.004英寸的温度下运行。WC（1 Pa）与占用空间的差值，有时在室外正压下。建筑空腔管道泄漏对能量、渗透和相对湿度的影响取决于泄漏气流速率以及进入泄漏的空气的温度和湿度条件。因此，建筑物空腔导管的位置非常重要。 如果返回的泄漏空气来自占用空间，则泄漏对能量、渗透或相对湿度的影响很小或没有影响。在另一个极端，如果泄漏的空气来自炎热潮湿的阁楼空间，影响会很大。本文讨论了各种建筑空腔管道泄漏与八种不同建筑结构的相互作用——基于天花板空间中一次空气和热边界的位置。本文的结论是，一般来说，建筑空腔不应被用作空气分配系统的一部分。例外情况是使用天花板空间回风静压箱。 天花板静压箱可设计为在室外接近中性压力下运行，因此，管道泄漏很少或没有。单位:双引证:研讨会，ASHRAE交易，1998年，第104卷，第2部分，多伦多

Field testing in 70 small commercial buildings in central Florida identified that building cavities were used as part of the air distribution system in 33 buildings. The various building cavity types (number of buildings in parentheses) are: enclosed air-handler support platforms (10), mechanical closets (8), mechanical rooms (6), ceiling spaces (7), wall cavities (6), chases (1), and "other" building cavities (2). Testing found that these building cavities are considerably more leaky than standard ducts and plenums because they are generally not built to the same airtightness standard as ducts. Actual air leakage is a function not only of duct hole size but also pressure differential across the leak sites. Pressure differentials generally range from -0.080 in.WC (-20 Pa) to -0.401 in.WC (-100 Pa) in support platforms, mechanical closets and rooms, wall cavities, and chases. By contrast, ceiling plenums often operate at less than 0.004 in.WC (1 Pa) difference from the occupied space and sometimes at positive pressure with respect to outdoors.The energy, infiltration, and relative humidity impacts of building cavity duct leakage depend upon the leak airflow rate and the temperature and humidity conditions of the air entering the leaks. Therefore, the location of the building cavity ducts is very important. If the return leak air is drawn from the occupied space, that leakage will have little or no impact on energy, infiltration, or relative humidity. At the other extreme, if the leaking air comes from a hot and humid attic space, the impacts will be large. The interaction of various building cavity duct leaks with eight different building configurations--based on the location of the primary air and thermal boundaries in the ceiling space--is discussed here. The paper concludes that building cavities should not, as a general rule, be used as a part of the air-distribution system. The exception is use of ceiling space return plenums. Ceiling plenums can be designed to operate at near neutral pressure with respect to outdoors and, therefore, can experience little or no duct leakage.Units: Dual