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Energy Cost Efficiencies for Cleanroom HVAC Systems

Cleanrooms are well known for being some of the highest energy consuming facilities in the world.  The intensive HVAC requirements for performing stringent airflow and pressurization functions within strict temperature and humidity control parameters…is a major reason.  Consuming anywhere between 10 to 100 times the amount of energy compared to normal office space…a cleanroom’s HVAC system can easily be responsible for over 50% of the entire facility’s energy costs. Having a profound impact on operating costs and overall profitability…achieving the necessary air cleanliness standards is the HVAC systems’s vital role in the production process.  And as overall demand grows …from existing technologies that become increasingly sophisticated…and new technologies that create additional demand…the controlled environments produced by highly efficient HVAC systems becomes more vital with each day.

Here are some selected key design strategies for reducing energy costs related to a cleanroom’s HVAC system:

  1. 1st Priority – Minimize demand:  Consider the building facility as a whole. Can efficiency of the building’s shell be increased? With new buildings, carefully orient and develop the building form. Is there an opportunity to reduce the volume of your cleanroom? Less volume equates to less air re-circulation with resulting HVAC savings.
  2. Accurately Scope the Square Footage Required & Cleanliness Level – Going overboard in either category will drive up your costs. Considering reducing positive pressurization where prudent.
  3. Flexibility – Design your HVAC system with scrutiny on flexibility…not only for sustainability’s sake…but for future product line and expansion capabilities as well.
  4. Subdivide the Facility’s Space Classifications. Carefully examine the proposed process and product requirements when determining your required cleanroom classification. Overkill is an easy trap to fall into. Do you really need the entire space to be stringently controlled?
  5. Invest in High Efficiency Equipment.  Upfront dollars invested in the best equipment… have surprisingly short payback periods.  Remember to use high efficiency filters too.
  6. Alternate Energy Sources – Use them appropriately to reduce the load on your HVAC system through careful analysis and appropriate design throughout the facility. Consider solar heating and power, daylight, wind energy, and thermal energy wherever it’s technically sound and fiscally responsible.
  7. Analyze the Viability of Reducing Air Change Rates (ACR).  Motors and fans sizes are driven largely by the air change rate in the cleanrooms. Larger motors and fans drive increased HVAC investment and operating costs. You can reduce power usage by approximately two-thirds if you reduce your ACR by approximately one-third.
  8. Adjust Airflow to Match Production Load. Scheduling software and timers can be used to decrease air recirculation and the HVAC load during periods of reduced production.  Occupancy sensors can make automatic adjustments depending on the occupancy levels of your biggest contaminant source—people.
  9. Locate Equipment Outside the Cleanroom when feasible. Locate process tools in an adjacent chaseway and provide critical clean access on the cleanroom side, you will reduce heat gain as well as the square footage required in your cleanroom, resulting in less demand on the HVAC system. This also makes future equipment maintenance easier and less costly.
  10. Variable Frequency Drives (VFDs). Variable frequency drives, which adjust HVAC equipment speed to match conditions, can cut your energy up to a third compared to constant speed drives.
  11. Use Particle Counters to Manage Airflow in Real Time. Carefully located optical sensors provide 24/7 particle counts to the building management system, allowing the HVAC system to operate with efficiency matched to need.
  12. Don’t Overdesign Your HVAC System – Being too cautious & conservative or cautious by building in too many safety nets. Those behaviors compromise operating efficiencies.

Lawrence Mechanical - Clean Room HVAC - San Jose CA

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