While most low humidity environments demand desiccant-type dehumidification processes, the predominant method for normal summer humidity controls is through cooling coils. A typical chilled-water coil or direct expansion (DX) coil can bring humid air down to 50° to 55°F dewpoint, thus maintaining space relative humidity (rh) under 60% at around 72°. For commercial applications, this relatively cold supply air does not need to be reheated. Rather, building controls can modulate the supply air through variable air volume (vav) boxes to meet varying cooling load.
For most industrial process environments, particularly pharmaceutical and micro-electronic industries, however, a fixed amount of supply air would be required. Thus the 50° to 55° supply air tends to overcool. The prevailing way of countering overcooling is to provide reheat coils to heat the air back up, resulting in simultaneous heating and cooling, and thus increased energy consumption.