A common problem in the average plant is “air starvation”. Exhaust systems throughout the structure may have been well designed for their intended purpose. However, no consideration may have been given to the replacement of exhaust air. As a result, the building may be under severe negative pressure. This situation reduces the efficiency of the exhaust fans and produces unhealthy and uncomfortable working conditions. Substantial economy and efficiency can be obtained by correcting this situation through the use of supply fans or “make-up air” units. Many buildings have adequate exhaust and supply fans to provide a comfortable environment for the occupants. Unfortunately, there may be little control over the distribution of the air to produce the desired results. Good planning will recognize the necessity for proper air distribution and circulation through the occupied areas of the building. Suitable deflectors and baffles can be incorporated where needed. “Booster fans” or air circulators can be positioned to take care of trouble spots and augment the direction and velocity of the air flow. Diffusers may be required lo assist in air distribution. Drafts and dead spots can thus be eliminated. All of these are inexpensive aids that can ensure that a well planned system will achieve its important objectives.
Exhaust fans are usually located near the area where heat-producing machinery is found in the industrial building. This has the very practical advantage of exhausting this superheated air near its source and preventing a heat build-up in other areas. If side wall locations are to be utilized for air intake or exhaust, it is desirable to consider the prevailing wind direction during the summer season. If the ventilation system can be oriented to take advantage of prevailing winds, the efficiency of the system may be increased considerably, Systems that incorporate roof exhausters are usually not affected by a prevailing wind.
Where air velocity is the critical factor in a breeze conditioning system, use of the “long dimension” of the building or room is highly desirable. By moving air through the long dimension, the cross-sectional area is reduced and less air volume is required to obtain the needed air velocity. A vital element in the successful breeze conditioning system is a supply of clean, cooler, fresh air. While such an ideal air supply may not be available, common sense dictates that air being supplied into the building should be from the best available source. Avoid recirculating air that has just been exhausted from the building or another nearby structure.
The noise level in most commercial and industrial buildings has become a highly critical matter. Although the ventilating equipment is only one item in the overall total, its effect should be carefully considered. If the normal noise level in the building is low, the noise level of the ventilating equipment should be low; if the background noise level is high, the amount of noise added by the ventilation system may be insignificant