Cleanrooms are expensive, and energy consumption is a major cost item in operation and maintenance. Some costs may be required, and expecting individual companies to challenge long-accepted design rules is unrealistic. As energy costs increase and companies strive to reduce their carbon footprint, planning and, if needed, redesigning the cleanroom can be a rewarding investment.

SIMPLICITY
KISS, Keep it Simple Stupid, is a key to minimizing energy costs for a cleanroom. Basically, if an operation doesn’t need to be performed in the cleanroom, keep it out! Too often, we observe processes performed in cleanrooms that either could or should be performed elsewhere.

All processes involving critical cleaning and surface preparation should not automatically be relegated to the cleanroom. Cleaning equipment, especially aqueous cleaning, takes valuable space and consumes energy. Heating process baths and drying components are energy- intensive steps. Unless heat exhaust paths are thoughtfully built into the design, heat is released into the cleanroom space and adds to the energy burden. These processes may also generate particle and thin film contaminants, resulting in more energy usage, more rework, and lower yields.

Cleanrooms typically must operate within tighter temperature control limits than other portions of the facility. Heating and cooling both are energy intensive, and the tighter the temperature limits, the more the push-pull heat-cool cycles consume energy. One study of cleanroom energy use¹ indicates that within the HVAC (Heating, Ventilation, and Air Conditioning) system, fans and pumps account for only 8% of the energy consumption; heating and cooling uses 92% (Figure 1). Heat from cleaning processes, that increases the thermal burden of the room, requires even more energy from the cooling system to keep room temperatures within limits.

The “clean” end of a cleaning system can often be conducted in a mini-environment. Components emerging from the cleaning system can then be carefully packaged to protect them from recontamination and transported into the cleanroom for final assembly.