The Question I Always Ask Engineers About Ventilation

Ventilation moves air. It does not remove contaminants at source.

When I speak with engineers about indoor air quality, there is one question I always ask.It’s simple - and it usually stops the conversation for a moment:

“What problem are you trying to solve with more ventilation?”

For decades, ventilation has been the default response to indoor air quality concerns. If air is “bad”, bring in more outside air. But in practice, this approach often treats the symptom, not the cause.

Ventilation Is a Transport Mechanism, Not a Cleaning Strategy

Ventilation moves air. It does not remove contaminants at source.

If indoor air contains particulate matter, VOCs, pathogens, or odours, increasing ventilation merely dilutes them - temporarily - at the cost of:

• Higher cooling loads

• Larger HVAC plant

• Increased energy consumption

• Higher operational carbon emissions

In hot, dusty climates like the GCC, this approach is particularly inefficient.

The Better Question: What Is in the Air?

Effective IAQ strategies begin by identifying:

• The contaminants present

• Where they originate

• Whether they can be neutralised indoors

Once contaminants are actively removed or neutralised, ventilation can be optimised, not maximised.

This is exactly what performance-based ventilation frameworks like ASHRAE 62.1 IAQP were designed to support.

Clean First. Ventilate Second.

When air is actively cleaned within the occupied space:

• Less outdoor air is required

• HVAC systems work more efficiently

• Energy use drops

• Comfort improves

Ventilation becomes a precision tool - not a blunt instrument.

The Takeaway

If your ventilation strategy assumes dilution is the only answer, you are likely:

• Overspending on energy

• Oversizing HVAC equipment

• Undermining Net Zero targets

The smartest buildings don’t ask how much air they can bring in.They ask how clean the air already is.