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Design – Case Study 1


Client Need


A 4,500 SF ISO 7 (class 10,000) cleanroom addition to an existing building was required for this semi-conductor facility as they expanded their production space. In addition to new HVAC distribution systems, new equipment selections included a custom make-up air handling unit with a fully integrated custom energy recovery system, custom recirculation air handling units, relocation of existing air handling units, heat and solvent exhaust fans, smoke exhaust fans, and ultrasonic humidifiers. New air handling equipment and humidification system was interfaced with existing building infrastructure.

Design Features

  • Basis of Design setpoints: 72 °F (± 2 °F) and 40% RH (± 10% RH).
  • Full sequence of operations for all new equipment including all interface points with existing equipment and systems.
  • Custom 25,000 CFM make-up air handling unit with fully integrated energy recovery system serving both the new facility and existing adjacent spaces. Incorporated new make-up air for adjacent spaces, which improved conditions of adjacent spaces while also addressing the requirement of the new addition. Ultrasonic humidification system interfaced with existing building RODI water system.
  • Custom recirculation air handling units for N+1 redundancy serving new cleanroom. Design included pre-filter selections for HEPA longevity and low capacity SCR electric reheat coil control for final temperature trimming.
  • Relocated existing air handling unit and coordinated final location with owner, architect and structural engineer. Designed and laid out reconnections of all existing utility and distribution systems.
  • Central process (solvent and heat) exhaust systems including fans for N+1 redundancy with controls and dampers for automatic changeover.
  • Designed and laid out high purity process piping including compressed dry air (CDA), extra dry compressed air (XCDA), nitrogen, hydrogen, process vacuum, and house vacuum systems including interface with new facility process plates located in the ceiling and/or walls.
  • Designed and laid out new stand-alone duplex process vacuum and pumping system to separate and manage wet RODI processes.
  • Designed, laid out and interfaced with existing system a new ordinary hazard, group 2, wet pipe sprinkler system for new facility.
  • Designed a new 3000 Amp, 277/480V, 3 phase, 4 wire distribution switchboard for new and future loads. Design included a new 27.6 KV primary, 277/480V secondary, 2500 KVA pad-mounted transformer with connection to the existing electrical primary switchgear.
  • Designed and laid out electrical distribution systems including branch circuit panels, transformers, and feeders. Voltage drop on feeders designed were not to exceed 3% and total voltage drop for feeders and branch circuits were not to exceed 5%.
  • Designed power for all HVAC and process mechanical equipment including feeders, disconnect switches, and motor controllers.
  • Designed power services for all facility equipment installed in new spaces. Included in design was a full perimeter layout of surface mounted raceway which housed various types of outlet configurations for connections to new equipment.
  • Designed and laid out all fire alarm services including interface with existing system.
  • Designed lighting using appropriate clean room fixtures recessed into ceiling grid system. Designed and coordinated automatic lighting control system with owner and architect and as required by code.
  • Designed emergency lighting system as required by code.

Design Benefits

  • Critical ISO 7 cleanroom areas have tightly controlled year round temperature to ±2.0 °F and relative humidity to ±10% RH.
  • Cascade pressure relationship between critical and noncritical areas to prevent infiltration and molecular contamination.
  • Achieved a robust production facility capable of operating continuously year round while maintaining strict environmental criteria.
  • Achieved greater year round temperature and humidity stability and quality of adjacent, existing facilities through incorporation and integration of new make-up air handling unit serving both new addition and existing areas.
  • Fully integrated energy recovery system provided year round operational energy savings for both the new facility and the adjacent areas served by the new make-up air handling unit with a total sensible reduction of 448 MBH (131 kW) wintertime and 207 MBH (17 Tons) summertime.