Demand Controlled Filtration in an Industrial Cleanroom

Abstract

In an industrial cleanroom, significant energy savings were realized by implementing two types of demand controlled filtration (DCF) strategies, one based on particle counts and one on occupancy. With each strategy the speed of the recirculation fan filter units was reduced to save energy. When the control was based on particle counts, the energy use was 60% of the baseline configuration of continuous fan operation. With simple occupancy sensors, the energy usage was 63% of the baseline configuration. During the testing of DCF, no complaints were registered by the operator of the cleanroom concerning processes and products being affected by the DCF implementation. IntroductionDemand controlled filtration (DCF) is a method of saving energy in cleanrooms by decreasing the recirculation fan speed when demand for filtration is low. A particle counter or an occupancy sensor can measure the demand for filtration. Another method of saving energy in cleanrooms is the use of programmable timers that decrease recirculation fan speeds when occupants are not expected, such as nights and weekends.

The Design of Cleanrooms for the Pharmaceutical Industry

“…The calculated DCF energy savings for Case study H ( Table 3 ) were higher than in other studies [13,[16][17][18] . The main reason for this was that the two rooms of Case study H showed a very low use time.…”

“…No sources need be assumed when the cleanroom is unoccupied. The control then simplifies considerably (occupied/unoccupied: ON/OFF), as do the investment costs [16] . If a production process has activities which are not directly coupled to persons present in the cleanroom, control on particle concentration may still present a feasible alternative.…”

“…A reduction of 33% fan speed contributes, for example, to a reduction in power consumption by 66% [15] . Previous studies have shown that DCF can result in annual energy savings of 28% to 72% [13,[16][17][18] . A third option for energy use reduction addresses the ventilation efficiency in the cleanroom.…”

Enabling advanced environmental conditioning with a building application stack

“…In our building, there are 25 RAHU units, each consuming 2-3 kW, with a total aggregate airflow of around 215000 cfm; this dwarfs the airflow in our 10 conference and class rooms, which is a total of about 5000 cfm. The potential to curtail RAHU operation when the cleanrooms are not in use could save large amounts of power; this is called demand-controlled filtration (DCF) [72].…”

Sustainable Scientists

“…That of the facilities benchmarked, half were operating below the lower range of typical practice (250 ACH) shows that great progress can be made by attending to a few especially energyintensive facilities (13). Real-time particle counting can be used to modulate ventilation speeds, thereby better managing energy demand (38). Expanded-area filtering can save energy by reducing pressure-drop and trim waste and maintenance costs thanks to less frequent replacement needs.…”