Page Navigation
How to Choose the Right HVAC Air Purification System
IAQ in Commercial Buildings
Not all commercial air purifiers work the same way. Each technology addresses indoor air quality (IAQ) differently, and choosing the right solution depends on how contaminants are removed, where purification occurs, and the impact on energy, maintenance, and performance.
The most important distinction to understand is the difference between passive and active air purification.
Passive vs Active HVAC Air Purification: What’s the Difference?
Passive Air Cleaning (Reactive)
Passive systems only treat air after contaminants are carried to the device by airflow. Their effectiveness depends heavily on ventilation rates, air circulation, and system run-time.
Examples include:
-
Mechanical filters
-
UV systems in return air
-
Sorbent (chemical) filters
-
Electrostatic precipitators
These systems clean air inside the HVAC unit, not in the occupied space where people breathe.
Active Air Cleaning (Proactive)
Active systems release cleaning agents (such as ions) into the occupied space itself, allowing contaminants to be treated at their source, including in the breathing zone and on surfaces.
This approach delivers broader, faster, and more consistent indoor air quality improvement - especially in large, high-occupancy buildings.
Back to top
Technologies for Indoor Air Quality Middle East
1. Media Filtration (MERV / HEPA)
How it works:
Filters trap particles as air passes through the HVAC system.
Key characteristics:
-
Effective for particle capture only
-
Performance depends on airflow and air changes
-
Higher efficiency filters increase static pressure
-
Increased fan energy and HVAC operating costs
-
Does not neutralize VOCs, odours, or microorganisms
-
Contaminants must reach the filter to be removed
Classification: Passive air cleaning
Back to top
2. Sorbent (Chemical) Filtration
How it works:
Uses activated carbon or chemical media to absorb gases and VOCs.
Key characteristics:
-
Effective only for gas-phase contaminants
-
Highly restrictive to airflow
-
Increases HVAC energy use
-
Requires frequent replacement
-
Spent media requires careful disposal
-
Limited application scope
Classification: Passive air cleaning
Back to top
3. Electrostatic Precipitation (EP)
How it works:
Uses high-voltage electrical fields to charge particles, which are then collected on plates.
Key characteristics:
-
Can capture very small particles
-
Low airflow resistance when clean
-
Requires frequent cleaning to remain effective
-
Does not neutralize VOCs or pathogens
-
Single-polarity systems may generate ozone
-
Performance degrades rapidly with poor maintenance
Classification: Passive air cleaning
Back to top
4. Dielectric Barrier Discharge (DBD) Bi-Polar Ionization
The Most Comprehensive Active Air Purification Method
Not all bipolar ionization systems are the same. Dielectric Barrier Discharge (DBD) is the most effective and extensively studied form of HVAC ionization.
How DBD Bi-Polar Ionization Works
-
Voltage is applied across a sealed ionization tube
-
A non-thermal plasma forms on the tube surface
-
Equal quantities of positive and negative oxygen ions are produced
-
Polarity alternates 60 times per second
-
Ions are distributed through the supply air into the occupied space
Why DBD Matters
-
Operates at energy levels that destroy ozone rather than create it
-
Sealed emitters prevent fouling and performance loss
-
Proven effectiveness against:
-
Fine and ultrafine particles
-
VOCs and odours
-
Bacteria, viruses, and mould
-
-
Over 50 years of global scientific research
-
Independently tested and validated
Performance in Real Buildings
A properly designed DBD Bi-Polar Ionization system:
-
Increases indoor ion levels to 500–1,500 ions/cm³
-
Replicates ion concentrations found in clean natural environments
-
Actively treats air in the breathing zone
-
Reduces dependence on high outdoor air volumes
-
Improves IAQ without increasing energy use
Classification: Active air cleaning
Why Active Air Purification Delivers Better Results
Unlike passive systems, active purification does not wait for contaminants to reach a filter. Instead, it:
-
Treats pollutants throughout the occupied space
-
Works continuously, regardless of airflow patterns
-
Improves air quality where people actually breathe
-
Enhances the effectiveness of existing HVAC filtration
-
Supports performance-based ventilation strategies (ASHRAE IAQP)
The Bottom Line
When selecting an HVAC air purification system, ask one key question:
Does it clean air only inside the duct - or throughout the occupied space?
Passive systems react.
Active systems protect.
For high-occupancy, continuously air-conditioned buildings - especially in hot, dusty climates - active air purification delivers cleaner air, lower energy use, and better long-term performance.
Key Takeaway
While these indoor air purification (IAQ)technologies are often described as “active,” their real-world effectiveness depends on ion persistence, spatial coverage, maintenance requirements, and validated performance data.
Active systems that:
-
Produce long-lasting ions
-
Distribute evenly throughout occupied spaces
-
Demonstrate independent, peer-reviewed validation
deliver significantly better outcomes for IAQ in Commercial Buildings
Back to top
Several active HVAC air purification technologies are commonly used in commercial HVAC systems. While each can contribute to improved indoor air quality, their mechanisms, effectiveness, persistence, and limitations vary significantly.
Needlepoint Bi-Polar Ionization (NBPI)
How Needlepoint Ionization Works
Needlepoint Bi-Polar Ionization uses a corona discharge created by applying voltage to rows of exposed metal needles or carbon-fiber brushes.
-
Each emitter alternates polarity, producing positive and negative ions
-
Ions are generated simultaneously from closely spaced needles
-
Installed in HVAC ductwork or near fan coil units
Performance Characteristics
-
Causes particle agglomeration
-
Provides limited gas-phase VOC breakdown
-
Classified as an active air purification method
Key Limitations
-
Low ion persistence: Simultaneous ion generation leads to rapid recombination, reducing effectiveness in large spaces
-
Limited microbial control: Operates at ~12.07 eV, insufficient to generate reactive oxygen species (ROS) required for pathogen inactivation
-
Minimal ion dispersion: Ions travel in a focused stream with limited diffusion into occupied spaces
-
Fouling risk: Open needles and brushes are exposed to contaminants, reducing performance over time
-
Location-dependent: Effective only when installed very close to the space being treated (e.g., fan coil units)
Summary:
NBPI is an entry-level active air purification technology suitable for small spaces, but performance is constrained in larger or high-air-volume environments.
Back to top
Ultraviolet Germicidal Irradiation (UVGI / UVC)
How UVGI Works
UVGI uses ultraviolet-C (UVC) light to deactivate microorganisms by damaging their DNA.
Typical Applications
-
Installed in air handling units (AHUs) or ductwork
-
Commonly used to keep cooling coils clean and reducebiofilm growth
Key Limitations
-
Requires prolonged exposure time (typically 3–6 minutes)
-
Not effective in occupied spaces
-
Only impacts pathogens that pass directly through the irradiation zone
-
Does not address particles, VOCs, or surface contamination
Classification: Passive air cleaning method
Back to top
Dry Hydrogen Peroxide (DHP)
How DHP Works
DHP systems attempt to convert ambient oxygen and moisture into low concentrations of hydrogen peroxide vapour.
Performance Considerations
-
Effectiveness depends heavily on ambient humidity
-
Limited independent testing and peer-reviewed validation
-
Hydrogen peroxide is proven effective at 3% liquid concentration, while DHP systems typically operate at ~25 parts per billion (ppb), orders of magnitude lower
Additional Concerns
-
Uses UVA bulbs containing mercury
-
UVA exposure has been associated with skin cancer risk
-
Designed primarily for microbial inactivation only
Classification: Active air cleaning method with limited validated performance
Back to top
Photocatalytic Oxidation (PCO)
How PCO Works
PCO systems generate hydroxyl radicals, which can deactivate microorganisms through oxidation.
Performance Characteristics
-
Highly effective in theory for microbial inactivation
-
Hydroxyl radicals have a very short lifespan (1–2 secs)
-
At typical air velocities, radicals travel only ~26 feet from this device
Key Limitations
-
Hydroxyl radicals cannot be directly measured, making performance difficult to quantify
-
Effectiveness is highly localized
-
Primarily targets microbes, not particles or VOCs
-
Also marketed as Photo-Hydro-Ionization (PHI), which uses the same principle
Classification: Active air cleaning method, but with limited reach
and persistence
Back to top