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Reducing Cleanroom Energy Consumption

Energy use has experienced new standards and regulations by governments mandating a reduction in CO2 emissions and energy wastage.  Cleanroom operators, in turn, must also consider energy consumption a key parameter to monitor.

Cleanroom HVAC equipment is heavily relied upon by the sector…since air handling units often run 24/7. Increasing HEPA filter usage and the need to control humidity and temperature also push up energy consumption.

Lawrence Mechanical HVAC Contractors - San Jose, CA

Monitoring energy use to benchmark yearly consumption in HVAC helps companies to meet today’s challenging regulations without compromising contamination control. ~ Steve Wake, Director Validair UK

In the pharmaceutical and medical sectors energy-expensive processes have become enshrined in the standards and are rigorously enforced. However, what is the ‘science’ behind these cleanroom design benchmarks that have such an influence on the present day operational ‘norms’?

The development of cleanrooms in the past 50 years shows that many of the key pharma HVAC control parameters have their origins in the cleanroom technology of the 1960s developed for the electronics industry; in particular, the evolution of cleanrooms as a result of NASA’s space travel programme in the 1950s and 1960s.

It is generally accepted that during this period the now familiar term laminar flow was introduced, as well as the specification of 0.46 m/s air velocity and the requirement for 20 air changes per hour. These concepts appear in cleanroom guidelines, regardless of their relevance or effectiveness in different industry sectors.

Air movement within the cleanroom is fundamental in determining the optimum air velocities and visualisation experiments involving smoke tests are key to understanding this. Airflow visualisation is typically performed once the facility has been fully completed and set into the effective mode of operation. The results of airflow visualisation are reviewed to ensure a minimum sweep of air is achieved within the facility. Often the actual operational characteristics of the facility are far in excess of the minimum sweep expectations.

Airflow visualisation can lead to energy savings when adjustments to the facility HVAC system can be made, selecting a lower air volume flow rate that satisfies the minimum clean air sweep expectations. Computational fluid dynamic simulations can also be used to assess the suitability of clean air sweep patterns at certain predetermined air volume flow rates.

Opportunities for energy savings can also be found in the “out of hours set back” a strategy regularly used in office environments. Here, air changes are reduced in facilities, or unused parts of the facility, overnight or at weekends. The proviso being that airflow must remain high enough to maintain the correct pressure cascade and validated operational status must be resumed before activities recommenced. These actions are easier to achieve when considered at the design stage of a new facility, rather than retrospectively.

 

Read More – Cleanroom Technology