States that makeup air for semiconductor clean spaces can vary from 5.08 L/s•m² to 50.81 L/s•m². Accordingly, the energy requirements to cool, dehumidify, preheat and/or humidify are significant and can represent 30% to 65% of the total thermal energy required to maintain a clean room environment. The greatest opportunity for significant energy savings can be achieved by reducing or displacing mechanical cooling or fuel-generated heating requirements. Presents and discusses various concepts of heat recovery, dual-temperature cooling, direct and indirect evaporative cooling and heat rejection directed towards makeup air systems that can achieve these objectives. In addition, explores equipment-sizing considerations not necessarily applicable to systems that are less energy-intensive or that operate continuously.

KEYWORDS: Clean rooms, make up, air conditioning, energy conservation, heat recovery.