Commercial Ventilation

By Author: Oleg Tchetchel
Total Articles: 31
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Humans are warm blooded animals whose normal body temperature is 98.6° Fahrenheit. However, we are most comfortable when the air temperature around us is in the 72°-to-78° range. If there is air motion around us, the effect of "wind chill", or evaporative cooling, enables us to feel comfortable in a much higher air temperature. As the natural air temperature in most non-air conditioned buildings is much warmer than outside air temperatures, the problem of keeping humans comfortable is primarily a cooling problem. Of course, this is not the case in periods of very cold weather. Our purpose is to discuss the environmental problems that frequently exist in periods of moderate to hot weather. An effective, economical solution of these problems is vital to the success of any business.

Almost any individual who finds himself in a situation or location that produces a feeling of discomfort quickly seeks relief from the problem. If there is no convenient solution to his discomfort, he may react in a number of ways. Invariably, the discomfort and his reaction to it has an adverse effect on his attitude, behavior and general ...
... efficiency in his job or responsibility. In almost any building or room used for commercial and industrial operations, it is quite likely that there are recurrent conditions that cause personnel discomfort. This is particularly true unless an expensive system for the circulation of refrigerated air (air conditioning) has been provided. In mild to hot weather, the discomfort of individuals is generally due to the build-up of intense heat within the structure. This becomes a severe problem in summer because the sun load on the building is added to the normal sources of heat build-up within the building. Most buildings have sufficient ventilation to remove smoke and fumes detrimental to health. However, it is unlikely that that system contributes very much toward the comfort of the individuals who occupy the mom or building.

If an individual is to produce maximum results, he must be allowed to function in an environment as nearly ideal as can be provided. In fact, the benefits in terms of efficiency and productivity can be substantial. Failure to provide a comfortable environment can be very expensive in terms of errors, work slow-down, complaints, absenteeism, etc. If the major factor is a hot, humid atmosphere, which may include smoke, dust, fumes or other irritants, a practical and effective approach to the problem is available. To obtain a reasonable degree of personnel comfort in hot weather, there are three basic factors that should be provided for in the ventilation and cooling system of a commercial or industrial building.

When the air temperature in the occupied area of a room or building exceeds 78° to 82°; most individuals begin to feel uncomfortably warm. The first step toward controlling the problem is to provide for the removal of excessively hot air from the building. This superheated air frequently mixes with the air in cooler areas of the building to produce an overall temperature increase. As superheated air is frequently localized around heat-producing machinery, it should be exhausted from the building near its source. This will prevent some undesirable air temperature increase in other areas. As a rule, outside air temperatures are considerably cooler than those inside a building. As superheated air is exhausted, provision should be made to replace it with fresh, cooler, outside air. Exhaust air in many areas of a building may have a temperature of 125° to 150°. This is usually the case where heat-producing machinery is in use. Similar air temperatures frequently occur near the roof or ceiling where rising warm air is trapped and further heated by the sun load on the roof. When this high temperature air is replaced by outside air, a substantial improvement in the average air temperature of the building results. Even where outside air temperature may be in the 80s or 90s, invariably it is 15° to 20° cooler than the air it replaces. This is a very important improvement to the individuals affected.

A very effective way to overcome the discomfort of a hot, stuffy room is to create a breeze. Before refrigerated air systems were invented, mechanical fans of every description were used to provide air circulation. The circulation of air over a person's body immediately causes a cooling effect on the skin. When air is passed over a moist surface, it will evaporate some of the moisture and thus lower the temperature of the surface. This is precisely what occurs when air circulates across the human body.

By creating a gentle breeze throughout a room or area, a great deal of cooling comfort is provided for individuals who must work there. This pattern of air circulation is called "breeze conditioning" by Buffalo Fan engineers. It is effective even when the air temperature may be 85°' to 95°. When this air circulation is achieved in combination with the factors mentioned in the paragraphs above, a very effective and practical solution is provided for the problem of personnel discomfort in hot weather.

Oleg Tchetchel
Canadian Process Design Engineer
Buffalo Fan Co.
http://www.buffalofan.com/hvac.html
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