Cleanroom energy saving options: set-back, fans, filters and air volume

By ZY Cleanroom · Updated 2026-11-01 · Sources at the end of the page

Options and where they come from

The first four rows come from HTM 03-01 Part A for hospital theatres. Check the rule of your own sector before you copy them.

Limits on set-back

A room in set-back must still return to its limits when work starts. EU GMP Annex 1 gives a guidance value of under 20 minutes for the clean-up period to reach the at-rest limits (para 4.29). Test the recovery time before you fix the set-back depth.

Pressure monitoring must stay on. Annex 1 requires critical pressure differences to be monitored and recorded continuously, with an alarm (para 4.16).

ISO 14644-16:2019 gives guidance on energy efficiency in new and existing cleanrooms. Its first edition was published in May 2019. Berkeley Lab's Cleanroom Energy Programming Guide (2001) is meant for the early programming stage.

Retrofit points from HTM 03-01

When a canopy is added, an existing air unit may need work. The fan may need re-rating for the new resistance. The cooling coil may need an upgrade for return-air fans and terminal lights (para 8.95).

Return-air fan heat may need cooling inside a modular unit. The extra load is sometimes met by conditioning the primary air instead (para 8.94).

The large canopy flow means the air must be recirculated or its energy recovered (para 8.80). An alternative to motion sensors links the air unit to the lights. General lights on gives set-back. Main lamp on gives full speed. All lights off gives off (para 6.13).

How to rank the options (suggested)

Ask three questions of each option. Does it cut air volume, fan power or running hours? Does it need requalification? Does your sector rule allow it?

Options that cut running hours leave the air in use unchanged, so they are a good place to start, but a set-back mode still needs its recovery tested.

Worked example (calculated)

Assume a design cuts air from 20 to 15 changes per hour, which is 0.75 of the flow. The textbook fan law says ideal fan power falls with the cube of the flow. So 0.75³ is 0.42, an ideal drop of 58 percent.

Real plants save less. Duct and filter resistance does not scale the same way, and a fixed pressure set point holds some of the load. Use the figure to rank options, and measure the real saving on site.

The arithmetic is not an excuse to cut air. FDA says higher rates are normally needed for ISO 7 and ISO 5, so qualify the lower rate first.

If you have a room list for a project where energy matters, send it to ZY Cleanroom and we will review the panel, door and ceiling scope with you.

Related guides

• How to Import a Cleanroom from China
• What a cleanroom costs to run: energy, filters and testing
• The Cleanroom Project Lifecycle
• How to choose a cleanroom contractor: questions and evidence
• Turnkey cleanroom contractor
• Room list builder

Sources

• NHS England, Health Technical Memorandum 03-01, Specialised ventilation for healthcare premises, Part A (published 22 June 2021; checked 1 November 2026)
• FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 1 November 2026)
• EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 1 November 2026)
• ISO 14644-16:2019, Cleanrooms and associated controlled environments, Part 16: Energy efficiency in cleanrooms and separative devices (first edition, May 2019; listing at SIS; checked 1 November 2026)
• Tschudi, Xu and Sartor, Cleanroom Energy Programming Guide (2001, Lawrence Berkeley National Laboratory; checked 1 November 2026)