Article
October 27, 2026
Life Science: CapEx decisions shape facility costs before construction starts
A cleanroom can meet every requirement on paper and still behave differently once people, materials, equipment, heat loads, and pressure changes begin to interact. Ramboll uses Computational Fluid Dynamics, or CFD, to test those realities before design decisions become expensive to change.
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Jens Chr. Bennetsen
Head of Center of Excellence
There is a particularly expensive moment to discover that a cleanroom facility does not behave as expected: when it has already been built.
Walls are in place. Ductwork has been installed. Diffusers have been positioned. Equipment has arrived. Commissioning has started. And people are trying to understand why airflow, pressure, or recovery times do not behave as expected.
There is a better time to ask those questions: when the facility still exists largely as a design and in computer models.
Test the cleanroom before you build it
CFD gives life science project teams a way to test how a cleanroom may behave before many design decisions become physical. It can model airflow, pressure responses, particle movement, heat loads, and the effects of people moving through the facility.
Used early, CFD can help project teams test operating scenarios, challenge assumptions, and understand how the complete cleanroom system is likely to behave before choices are locked into steel, ductwork, concrete, and equipment.
Ramboll’s work with the Technical University of Denmark on the Cellerator project demonstrated the value of modelling an interconnected cleanroom system rather than treating every room as a separate space.
“CFD gives us the opportunity to test the cleanroom while changes are still relatively easy to make. We can open doors, move people through the facility, change airflow, and test different operating scenarios before any of it has been built,” says Jens Christian Bennetsen, Head of Centre of Excellence, Advanced Simulations at Ramboll.
Future-proofing does not mean putting more capacity everywhere.
Head of Centre of Excellence, Advanced Simulations. Ramboll.
At the Cellerator project, Ramboll’s CFD modelling showed that excessive airflow could create turbulence and unnecessary energy use. By looking at airflow distribution and the positioning of diffusers and extraction points, the project could test how to improve performance rather than simply increasing air volumes.
More air is not automatically better
Cleanroom design naturally puts contamination control first. One obvious response is therefore to increase airflow.
But adding more air does not automatically deliver a better-performing cleanroom.
At Cellerator, the modelling showed that increasing airflow could reduce particle concentrations, but excessive airflow could also create turbulence and unnecessary energy use. The work identified opportunities to improve diffuser and extraction-point positioning, helping direct airflow more effectively rather than simply increasing volumes.
Airflow also affects fans, ductwork, filtration, controls, heating and cooling demand, and the energy consumed throughout the facility’s operating life. Oversizing can therefore increase both capital and operating costs.
Jens Christian Bennetsen says: “Future-proofing does not mean putting more capacity everywhere. With cleanrooms, the better question is whether the air is moving in the right way, under the conditions the facility will actually experience.”
Find the problem while it is still a design decision
One of the biggest benefits of CFD is changes when a project can discover a problem.
If modelling shows that a diffuser creates an undesirable airflow pattern, its position can potentially be changed in the design. If opening a door disrupts a pressure cascade, different solutions can be tested. If a material route creates an unexpected contamination risk, the layout or operating sequence can be reconsidered. If a higher air-change rate adds energy demand without delivering a corresponding performance benefit, alternatives can be compared before equipment is sized.
CFD does not replace commissioning, qualification, or physical validation. It gives the project team another opportunity to challenge assumptions before reaching those stages.
That is where Ramboll can add value early. By combining advanced simulation with cleanroom and facility design expertise, project teams can test how layouts, flows, HVAC strategies, and operating scenarios interact before changes become difficult or costly to make.
Key takeaways
Five questions to ask before design freeze
1
What happens if production volumes increase or decrease?
2
What happens if the next product changes people, material, or equipment flows?
3
How does the cleanroom respond when doors open and pressure conditions change?
4
Are we adding airflow because it improves performance, or because it provides a comfortable design margin?
5
Which cleanroom decisions would be hardest to change five or ten years from now?
Connect cleanroom design to the wider facility
This is also where CFD connects directly with Ramboll’s guide, Future-fit your life science site.
The guide looks at the decisions that shape whether a facility remains resilient and competitive over time. For cleanrooms, some choices become particularly difficult to revisit once the building and major infrastructure have been fixed. Layout, structural dimensions, primary utility corridors, shafts, and the wider cleanroom strategy can shape the facility for many years.
The guide recommends applying simulation early to validate layouts, flows, and system performance before design is frozen, while considering several credible production scenarios rather than one fixed forecast.
That turns the cleanroom conversation into more than compliance. It becomes a question of CapEx, energy, operational performance, commissioning, flexibility, and the ability to accommodate future production.
“The most valuable simulation is often the one that challenges an assumption. If the model simply confirms what we already expected, that is useful. But if it finds something we had not considered before construction, that can change the project,” says Jens Christian Bennetsen.
If an important assumption can be tested before it becomes steel, ductwork, concrete, and equipment, that is probably the right time to test it.
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