MC-PDIY22
为了确保高质量的通风空气并将所需的空气量降至低，室外进气口的位置必须避免建筑物排气、车辆排放和其他污染源。室内排气系统应在其源头收集异味或污染物。建筑物所需的通风量可以通过空气清洗器、高效过滤器、吸收化学品（如活性炭）或气味调节系统来减少。通风要求因居住人数和空间的预期用途而异。有关空间类型、占用水平和所需通风的详细信息，请参阅ASHRAE标准62。图14显示了提供100%室外空气的通风系统。这种类型的通风系统通常用于气味或污染物源于空调空间的地方（例如，排气罩和风扇清除烟雾的实验室）。此类应用需要调节补充空气，以提供可接受的环境。排至室外排风机回风空间补风送风机盘管过滤器室外送风C2711图14。使用100%室外空气的通风系统。在许多应用中，能源成本使得100%室外空气定容系统不经济。因此，可以使用其他控制内部污染物的方法，如可变容积通风柜控制、空间增压控制和空气净化系统。使用回风的通风系统（图15）比100%室外空气系统更常见。回风通风系统再循环系统中的大部分回风，并添加室外空气进行通风。回风系统可能有一个单独的风扇来克服管道压力

To ensure high-quality ventilation air and minimize the amount required, the outdoor air intakes must be located to avoid building exhausts, vehicle emissions, and other sources of pollutants. Indoor exhaust systems should collect odors or contaminants at their source. The amount of ventilation a building requires may be reduced with air washers, high efficiency filters, absorption chemicals (e.g., activated charcoal), or odor modification systems. Ventilation requirements vary according to the number of occupants and the intended use of the space. For a breakdown of types of spaces, occupancy levels, and required ventilation, refer to ASHRAE Standard 62. Figure 14 shows a ventilation system that supplies 100 percent outdoor air. This type of ventilation system is typically used where odors or contaminants originate in the conditioned space (e.g., a laboratory where exhaust hoods and fans remove fumes). Such applications require make-up air that is conditioned to provide an acceptable environment. EXHAUST TO OUTDOORS EXHAUST FAN RETURN AIR SPACE MAKE-UP AIR SUPPLY FAN COIL FILTER OUTDOOR AIR SUPPLY C2711 Fig. 14. Ventilation System Using 100 Percent Outdoor Air. In many applications, energy costs make 100 percent outdoor air constant volume systems uneconomical. For that reason, other means of controlling internal contaminants are available, such as variable volume fume hood controls, space pressurization controls, and air cleaning systems. A ventilation system that uses return air (Fig. 15) is more common than the 100 percent outdoor air system. The returnair ventilation system recirculates most of the return air from the system and adds outdoor air for ventilation. The return-air system may have a separate fan to overcome duct pressure