IAQ - What Engineers Get Wrong About It

Engineers are trained to be precise, evidence-driven, and standards-focused. That discipline has delivered safer buildings, better energy performance, and remarkable technical progress. Yet when it comes to air purification, even experienced engineers often make assumptions that limit performance, increase cost, or miss the real objective altogether.

Air purification is not simply an accessory to HVAC design. Done properly, it is a system-level strategy that directly affects health, energy use, equipment life, and building resilience. Here are the most common mistakes - and how to rethink them.

1. Treating Air Purification as “Just Filtration”

The most widespread misconception is that air purification equals better filters.

High-efficiency filtration is important, but it is only one piece of the puzzle. Filters primarily capture particles that physically pass through them. They do little to address:

• Gaseous pollutants (VOCs, ozone, NOx, SOx)

• Ultrafine particles that bypass or load filters quickly

• Pathogens circulating in occupied spaces

• Contamination on surfaces and coils

Relying solely on filtration often leads to higher pressure drops, increased fan energy, and more frequent maintenance - without meaningfully improving real-world air quality.

Purification is not just capture. It is control.

2. Designing for Air Changes, Not Exposure

Engineering calculations tend to focus on air changes per hour (ACH), dilution rates, and outdoor air percentages. These metrics are useful, but they don’t measure what actually matters: what occupants are breathing.

A room can meet ventilation requirements and still have:

• Poor air mixing

• Localised pollutant build-up

• High pathogen concentration near occupants

Air purification technologies that actively treat air within the space reduce exposure directly -rather than hoping dilution alone will solve the problem.

Compliance does not equal protection.

3. Assuming More Outside Air Is Always Better

Increasing outdoor air is often presented as the safest solution. In reality - especially in the GCC - it introduces serious challenges:

• Dust, sand, and PM infiltration

• High humidity loads

• Increased cooling and dehumidification energy

• Greater system wear and corrosion

In hot and humid climates, excessive outdoor air can degrade indoor air quality and energy performance at the same time.

Smart purification allows buildings to clean recirculated air effectively, reducing dependence on outside air while maintaining health and safety.

4. Ignoring What Happens Beyond the Ductwork: IAQ - What Engineers Get Wrong

Engineers often focus on what happens inside the air-handling unit. But contaminants don’t stop at the AHU.

Pathogens and pollutants exist:

• In occupied zones

• On surfaces

• Inside coils, drain pans, and duct linings

If purification only occurs at the air handler, contaminants can continue circulating within spaces and re-enter the breathing zone.

Effective air purification strategies treat the entire air ecosystem, not just the mechanical room.

5. Treating IAQ as a Comfort Issue, Not a Risk Issue

Historically, indoor air quality has been framed as a comfort or wellness feature. That mindset underestimates its importance.

Poor air quality is directly linked to:

• Increased illness and absenteeism

• Reduced cognitive performance

• Equipment corrosion and failure

• Liability in healthcare, hospitality, and education

In mission-critical and high-occupancy buildings, IAQ is fundamentally a risk management issue - not an optional upgrade.

6. Designing for Capital Cost Instead of Lifecycle Cost

Air purification is often value-engineered out because of perceived upfront cost. What is frequently missed are the lifecycle benefits:

• Lower fan energy due to reduced filter loading

• Extended equipment life

• Reduced cleaning and maintenance

• Fewer complaints, callouts, and retrofits

When viewed over the life of the building, effective purification often delivers a net operational saving.

The cheapest system to install is rarely the cheapest system to operate.

7. Not Monitoring What Matters

Many buildings claim to have “good IAQ” without measuring it.

Without real-time data on particulate levels, VOCs, humidity, and system performance, engineers are designing blind - and operators are reacting after problems arise.

Modern purification strategies work best when paired with continuous monitoring and data-driven control.

If you’re not measuring it, you’re not managing it.

IAQ - What Engineers Get Wrong

Air purification should not be treated as a bolt-on device or a marketing feature. It is a core engineering discipline that sits at the intersection of:

• Mechanical design

• Energy efficiency

• Health and safety

• Asset protection

As standards evolve and expectations rise - particularly in healthcare, education, hospitality, and high-performance buildings - engineers have an opportunity to lead rather than follow.

Getting air purification right is no longer about meeting minimum requirements.It’s about designing buildings that perform - every hour of every day.