Buyer guide
What a cleanroom costs to run: energy, filters and testing
Running cost has three drivers: fan and conditioning energy, filter changes, and scheduled testing and monitoring. Energy is the largest in the studies cited here, and much of it moves and conditions air.
By ZY Cleanroom · Updated · Sources at the end of the page
Energy: where it goes
The LBNL figures date from 2001, so they are dated. HTM 03-01 is healthcare guidance. Treat all of these as direction, not a forecast for your plant.
| Source | Finding |
|---|---|
| LBNL, 2001 (dated) | Cleanroom air systems are extremely energy intensive compared with commercial buildings. Most HVAC energy goes to the recirculation system |
| LBNL, 2001 (dated), citing an earlier study | HVAC was 36 to 67% of total cleanroom energy in three California facilities |
| LBNL, 2001 (dated), citing a review | Energy cost could reach 65 to 75% of total annual operation and maintenance cost in Europe |
| HTM 03-01, 2021 | Fans use about 40% of all electricity in ventilation systems |
| ISPE Pharmaceutical Engineering, 2021 | Pharmaceutical cleanrooms can use up to 15 times more energy than commercial building systems, with more than 50% of electricity used by plant HVAC |
What changes fan energy
Class. In the rooms LBNL measured for its 2001 paper, recirculation fan power per area was greater at higher cleanliness for the same system type. LBNL advises against specifying more cleanliness than the process needs. ISPE (2021) lists avoiding over-specification of the class as an energy measure.
Air path. Among the ISO 5 and ISO 5/6 rooms LBNL measured, fan power ranged from 2.8 to 24.1 W/ft² (about 30 to 259 W/m², converted), more than eightfold. LBNL ties such variation to design and layout. Lower resistance in the air path means less power.
Airflow. ISPE (2021) notes that fan power depends on the cube of the airflow rate. In one LBNL case, cutting recirculated air by 10% in one ISO 4 room and 20% in another would in theory cut fan power by up to 30 to 50%. ISO 14644-16:2019 gives guidance on optimising energy use in cleanrooms.
Filter grade and fans. HTM 03-01 (para 8.101) says a higher filter grade in an ultra-clean ventilation unit adds resistance, with penalties in fan power, energy use and noise. It recommends electronically commutated fans as the most energy-efficient.
Operating mode
HTM 03-01 (paras 6.1 and 6.2) calls switching off when not needed the most efficient policy, and setting back to a minimum the next best. Para 7.12 adds that setback extends the life of filters and components.
In a sterile facility, Annex 1 (para 4.14) asks for positive pressure under all operational conditions. Any setback there needs the owner's validation.
Filters
Filter cost is the filter, the labour, the downtime and the retest. HTM 03-01 (para 11.23) asks for filter gauges marked with initial and final resistance. A coarse return filter extends the life of the terminal filter (para 8.104).
A failed leak test means replacement, or repair of a limited area (FDA, 2004). Uneven velocity across a filter is also a reason to replace it. A change of final filters is a change to consider for requalification (Annex 1, para 4.32). No source here sets a replacement interval. Ask the supplier for initial and final resistance and a design life.
Testing and monitoring
| Item | Interval or mode | Source |
|---|---|---|
| Requalification, grades A and B | 6 months at most | Annex 1, para 4.32 |
| Requalification, grades C and D | 12 months at most | Annex 1, para 4.32 |
| HEPA leak test, aseptic room | Twice a year, as an example | FDA, 2004 |
| Grade A particles | Continuous, at least 28 L/min | Annex 1, paras 9.16, 9.17 |
| Critical pressure differences | Continuous, recorded | Annex 1, para 4.16 |
Example: lines to request, with no amounts
Example only. Ask the designer for these inputs, then cost them with your own energy and service rates.
| Cost line | Ask the designer for |
|---|---|
| Fan electricity | Fan power at design airflow, and the full, setback and off modes |
| Heating, cooling, humidity | Coil loads and outdoor air volume |
| Filter changes | Filter count, initial and final resistance, expected cycle |
| Testing | Tests per room per year, and who performs them |
| Monitoring | Sensors, counters and calibration cycle |
Who approves the room
Your regulator judges the facility, not the contractor. The contractor builds to your room data sheet and supplies test data. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor.
Questions
Common questions
What is the biggest running cost of a cleanroom?
Energy, in the studies cited. An LBNL paper from 2001, now dated, cites a European review in which energy cost could reach 65 to 75% of annual operation and maintenance cost.
Does a higher class cost more to run?
In the rooms LBNL measured in its 2001 paper, fan power per area was greater at higher cleanliness. Do not specify a class above what the process needs.
How often are HEPA filters replaced?
No source here sets an interval. Triggers are a failed leak test, uneven velocity, damage, or resistance reaching its final value.
Can I switch the system off at night?
HTM 03-01 calls off the most efficient mode when a space is not in use. In a sterile facility, Annex 1 asks for positive pressure under all operational conditions, so the owner must validate any setback.
Related guides
- The Cleanroom Project Lifecycle
- How to audit a cleanroom panel factory, on site or by video
- Writing a cleanroom URS: contents and testable wording
- How long does it take to build a cleanroom?
- Turnkey cleanroom contractor
- Room list builder
Sources
- Xu T and Tschudi W, Energy Performance of Cleanroom Environmental Systems, Lawrence Berkeley National Laboratory report LBNL-49106 (November 2001, dated; checked 31 October 2026)
- Moia E, Pharmaceutical Cleanroom Design and ISO 14644-16, Pharmaceutical Engineering, ISPE (September/October 2021; checked 31 October 2026)
- ISO 14644-16:2019, Cleanrooms and associated controlled environments, Part 16: Energy efficiency in cleanrooms and separative devices (preview copy on iTeh Standards, scope; checked 31 October 2026)
- NHS England, Health Technical Memorandum 03-01, Specialised ventilation for healthcare premises, Part A (published 22 June 2021; checked 31 October 2026)
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 31 October 2026)
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 31 October 2026)
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