Demand-controlled Filtration

The primary energy service provided in cleanrooms is the management of particles in the space. The acceptable level of particles depends on the use of the space, as indicated by the cleanroom specification. Ventilation is a means to the end, but the question of whether higher levels of ventilation necessarily yield higher levels of cleanliness has not been adequately addressed. LBNL began its research on this topic in the mid-1990s, which focused on analyzing the potential for dynamically managing ventilation rates in response to real-time particle-count measurements. By doing so, desired environmental conditions can be maintained without excessive energy use. The results of a recent field study were very positive, indicating an economic payback time of 1 to 4 years, depending on whether or not the facility's ventilation system is already equipped with a variable speed drive. Industry receptiveness to this thinking is evident in a site benchmarked by the LBNL cleanrooms project, where substantial nighttime ventilation setbacks in a Class-100 cleanroom were found not to compromise the process.