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Laboratory & cleanroom3 min readLast updated September 2026

Comparing fume cupboards properly: safety per cubic metre of air

Anyone who selects fume cupboards by price or maximum airflow is comparing the wrong thing. What matters is how securely a fume cupboard provides containment with how little air – with 100 or more fume cupboards, this becomes the single biggest lever in the entire ventilation system.

Key points

  • More exhaust air does not automatically mean more safety – it can create turbulence, draughts and high operating costs.
  • A fair comparison relies on tested values to EN 14175: containment, robustness, airflows at part load and full load, and pressure drop.
  • Small differences per fume cupboard add up: just 25 m³/h more per fume cupboard amounts, across 100 fume cupboards, to the capacity of a dedicated air handling unit.
  • Missing manufacturer data are not a neutral value but a risk.

01The fallacy: more air equals more safety

When fume cupboards are selected, the discussion usually starts with purchase price, width, material and appearance. The bigger lever lies elsewhere: how much air does a fume cupboard have to move continuously in order to contain hazardous substances safely? Extracting a lot of air is not a technical achievement. The achievement lies in remaining reliably safe with as little air as possible.

Excessive or poorly guided airflows create disturbance at the workstation, draughts and turbulence – and they drive up operating costs for decades. Airflow on its own is therefore not a mark of quality.

02Four quantities that count together

  1. Containment – do hazardous substances stay inside the fume cupboard?
  2. Robustness – does containment remain stable when someone walks past or a door opens?
  3. Airflow – how much air does the fume cupboard need for this, with the sash closed and open?
  4. Pressure drop – how much fan work does it cause?

The standard EN 14175 provides the method for testing these quantities under defined conditions. Anyone who tenders fume cupboards merely as “compliant with EN 14175” forgoes precisely the figures that make the difference.

03How a few cubic metres turn into an air handling unit

Two tested fume cupboards of the same size often differ by only a few dozen cubic metres of air per hour in the open state. That seems negligible – until you multiply it by the number of units.

Calculation example with assumed values: a difference of 25 cubic metres per hour times 100 fume cupboards gives 2500 cubic metres per hourPER FUME CUPBOARD+25m³/hassumed differenceper fume cupboard×ASSUMED: 100 FUME CUPBOARDS=ADDITIONAL AIR2500m³/h – an air handlingunit of its ownFan & electricityDucts & shaftsHeating, cooling, humidifyingNoise & operation over decades
Small difference, big impact Calculation example with assumed values

Let us assume a research building with 100 identical bench-mounted fume cupboards. If each of them needs just 25 m³/h more, the total is 2500 m³/h – the capacity of a dedicated air handling unit, including ducts, shafts, and heating, cooling and humidification energy. This decision is not made in the plant room, but when the fume cupboard is selected.

04Rules of thumb versus tested values

The lever becomes even greater when a system is sized with blanket empirical values rather than tested fume cupboard data. Rules of thumb contain safety margins from a time when fume cupboards needed considerably more air – modern, tested fume cupboards often manage with noticeably less. Anyone who plans with blanket values builds the difference in as ductwork, equipment and energy consumption for decades.

This does not mean that the fume cupboard with the lowest figure always wins. A fume cupboard with slightly less air but a high pressure drop can perform worse in energy terms than one with slightly more air and very low resistance – fan work grows with the product of the two. And in variable operation, what counts above all is how far the fume cupboard can turn down in the closed state and how consistently the sashes are closed.

05What you should require in the tender

  • Type test report to EN 14175 for exactly the design and width offered
  • Airflows in the closed and open state
  • Containment and robustness values in ppm, with mean and maximum stated separately
  • Pressure drop at maximum airflow
  • Sound levels
  • Measurement and balancing on site in the installed state

If any of this information is missing, this should remain visible in the evaluation – as a documentation gap, not as a neutral value.

Takeaway

A good fume cupboard is not the one that extracts the most air, but the one that demonstrably remains safe – with as little air, pressure drop and energy as possible.

Standards and sources

  • EN 14175-3 – Type test methods for safety and performance of fume cupboards
  • EN 14175-6 – Variable air volume fume cupboards
  • Lawrence Berkeley National Laboratory – Energy Use and Savings Potential for Laboratory Fume Hoods

SEDC AG · Article from our internal training series “Technik Praxis”, abridged for clients and users.

Full version & expert discussion

More depth for your project.

The full version contains the complete evaluation methodology with an efficiency map, the calculation of annual air volume in variable operation and our requirements list for tenders. We are happy to go through it with you – applied to your installation.

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