2% for perfection
Introduction
Cleanrooms are among the most expensive construction projects imaginable.
You can usually expect to pay between €1,000 and €5,000 per square meter, and in semiconductor manufacturing or lithography, the cost can quickly rise to €15,000 to €20,000 per square meter.
A cleanroom with an area of 1,000 m² therefore easily costs a million euros – and yet many builders and operators forego a measure that accounts for just 2% of the investment costs but brings massive added value: CFD simulation for flow and particle optimization.
Why? I wanted to know. And as always, when something bothers me, I start calculating.
The status quo: high-tech rooms – built on gut feeling
After a few discussions with cleanroom suppliers and manufacturers, a surprisingly consistent picture emerges:
Simulations are rarely used—and when they are, it's only after something has gone wrong.
An example: Air flow carries contaminants to precisely where the most sensitive processes take place. Or a supposedly good filter configuration creates vortices that return particles to the work area.
In these cases, people like to call in the “computer people” – i.e., Merkle CAE Solutions – to understand the disaster and, if possible, repair it.
But it would be so much cheaper (and more honest) to ventilate digitally beforehand instead of counting the dust afterwards.
The calculation example: 2% effort versus 100% hassle
Let's take a clean room with construction costs of €1 million.
A CFD simulation of flow and temperature distribution typically costs between €5,000 and €20,000, or 1–2% of the total investment.
What do you get in return?
- Optimized airflow that removes particles in a targeted manner instead of distributing them.
- Verified temperature fields to protect sensitive equipment.
- Early detection of dead zones that would only be noticed in reality through measurement or troubleshooting.
- And above all: certainty that the system works before the first filter is installed.
In relative terms:
€20,000 for a simulation is cheaper than a single dissatisfied end customer who refuses to accept their system because dust is settling on the lens.
Simulation = Prevention
The argument that “we only simulate when there are problems” is like only checking the structural integrity of a skyscraper when it starts to lean.
Especially with complex cleanroom airflows, the interaction between air velocity, temperature, filters, ceiling and wall structures, and equipment is highly nonlinear. An incorrectly positioned air outlet can undermine the entire zone logic.
CFD (computational fluid dynamics) simulations make it possible to visualize these effects in advance - including particle trajectories, flow velocities, and pressure distributions.
The result: planning reliability. And, ideally, a cleanroom that delivers what its certificate promises.
When engineers listen to their intuition – and the airflow laughs
In conversations, you often hear:
“We've always done it this way, and it works.”
That may be true—as long as it works. But flow is capricious.
It doesn't like to stick to empirical values. Even small geometric changes, a different machine setup, or modified process conditions can completely change its behavior.
Simulation, on the other hand, provides hard data instead of soft assumptions.
Or, to put it in engineering humor:
“Perceived flow velocity is not a measurable quantity.” 😉
Conclusion: If you're building for $1 million, you should be thinking in terms of $20,000.
Investing in a CFD simulation is not a luxury, but rather insurance against planning errors that cannot be corrected later.
Especially in industries where clean rooms are standard - semiconductors, pharmaceuticals, medical technology, optics - air quality can mean millions.
So if you have the courage to invest in prevention rather than complaints later on, you will get:
✅ better performance,
✅ more satisfied customers,
✅ and, in the best case scenario, no calls about “inexplicable” dust problems.
Yours Stefan Merkle
PS: You can find an example of a customer project we supported in the aerospace industry HERE.