Two technologies dominate advanced air purification in commercial HVAC systems in 2026: HEPA filtration, which physically captures particles as air passes through a dense fibre matrix, and UV-C irradiation, which inactivates biological contaminants using germicidal ultraviolet light.The facilities that achieve the highest indoor air quality outcomes deploy both technologies in the right sequence and maintain both correctly — which means understanding exactly what each does, where each fails, and what a structured PM programme for each looks like. Sign up free to build PM schedules for your HEPA and UV-C assets in OxMaint, or book a demo to see the preventive maintenance workflow configured for your building's air purification systems.
Track HEPA and UV-C Maintenance — Automated PM Schedules, Lamp Hour Counters, and Filter Change Alerts in One Place
OxMaint's Preventive Maintenance module registers every HEPA filter bank and UV-C lamp as a tracked asset — with condition-based change schedules, operating hour logs, and full compliance documentation.
How Each Technology Actually Works — The Mechanism Behind the Marketing
Understanding the physics of HEPA and UV-C is the foundation of specifying, installing, and maintaining them correctly. Both technologies are frequently mis-specified or under-maintained because the mechanism is misunderstood — HEPA filters installed with bypass gaps that defeat the entire capture system, or UV-C lamps running at 40% of rated output because nobody checked the lamp hours. Book a demo to see how OxMaint's preventive maintenance module tracks lamp hours, filter differential pressure, and replacement schedules for both technologies.
HEPA — Three Capture Mechanisms
01
Interception
Medium-sized particles (1–10μm) following airflow streamlines come close enough to a fibre to be captured by contact. No deviation from airflow path required — pure proximity capture.
02
Impaction
Large particles (above 1μm) have too much inertia to follow airflow around fibres — they continue in a straight line and collide directly with fibre surfaces. More effective at higher face velocities.
03
Diffusion
Ultra-fine particles (below 0.1μm) undergo Brownian motion — random thermal movement that increases their probability of fibre contact. This is why HEPA captures nano-particles more efficiently than 0.3μm particles.
The 0.3μm MPPS (Most Penetrating Particle Size) represents the worst case — where diffusion and impaction both have minimal effect. HEPA is rated at this size specifically because it is hardest to capture.
UV-C — Dose-Response Inactivation
01
DNA/RNA Photodamage
UV-C photons at 254nm are absorbed by nucleic acids (DNA and RNA). This forms pyrimidine dimers — covalent bonds between adjacent bases that block replication. The organism cannot reproduce and is rendered non-infectious.
02
The Dose Equation
Inactivation = UV intensity (mW/cm²) × exposure time (seconds) = fluence (mJ/cm²). Each pathogen has a characteristic dose for 90%, 99%, and 99.9% inactivation. Correct system sizing requires calculating actual dose delivered to moving air — not just lamp output.
03
Lamp Degradation
UV-C mercury lamps lose germicidal output over time — typically 15–20% loss by 8,000 hours. A lamp running at 80% output may be delivering only 60% of the design dose to moving air once distance and reflectance are accounted for. Lamp hour tracking is mandatory.
Shadowing is the critical failure mode — organisms in the wake of duct components, coil fins, or other UV-C lamps receive zero dose regardless of lamp output. Lamp placement geometry determines actual system effectiveness.
Head-to-Head Effectiveness: What Each Technology Kills, Captures, or Misses
The most important principle in air purification specification is that no single technology addresses all indoor air quality threats. HEPA and UV-C have complementary effectiveness profiles — deploying them together covers threats that neither addresses alone. The comparison below covers the six primary categories of indoor air contaminants relevant to commercial buildings. Sign up free to log air purification assets and their PM schedules in OxMaint.
High — captured by fibre impaction
Excellent — high UV sensitivity
Maximum
Moderate — captured in respiratory droplets; free virions can pass HEPA at rated MPPS
Excellent — UV-C inactivates free virions and droplet-bound viruses
Maximum
High — spore size well within HEPA impaction range
Moderate — requires higher dose; best for surface (coil) application
Very High
PM2.5 Particles
Below 2.5 μm
Excellent — HEPA's primary particle removal application
None — UV-C does not remove non-biological particles
High (HEPA only)
None — HEPA captures only particles, not gaseous pollutants
Limited — UV-C can break down some VOCs at high dose (photocatalysis)
Low — add activated carbon
Coil Biofilm
Surface contamination
None — HEPA addresses airborne particles only
Excellent — coil irradiation is UV-C's single most cost-effective commercial application
Maximum (UV-C only)
Maintenance Requirements — Where Most Systems Fail in Practice
Both HEPA and UV-C systems are frequently installed, commissioned, and then effectively forgotten — left to degrade while building managers assume they are still performing at specification. A HEPA filter loaded to bypass point is worse than no filter because it creates a false assurance of protection. A UV-C lamp at 30% of rated output has no meaningful germicidal effect on a moving air stream. Neither failure is visible without structured monitoring. This is the core PM challenge for both technologies — and the reason OxMaint's preventive maintenance module exists. Book a demo to see HEPA and UV-C PM schedules built out in OxMaint.
Frequency
Task
Why It Matters
Weekly
Read differential pressure gauge across filter bank
Only reliable indicator of filter loading and bypass risk
Monthly
Inspect filter housing gaskets and frame seal integrity
Bypass at seal points defeats filter performance regardless of media condition
At ΔP threshold
Replace filter — log date, differential reading, and unit ID
Calendar replacement often too early or too late — condition-based is correct
At replacement
Bag-in bag-out containment protocol — filter handling procedure
Loaded HEPA filter is a concentrated biological hazard — improper removal aerosolises captured pathogens
Annual
Filter bank integrity test (DOP/PAO aerosol challenge test)
Verifies no pinhole leaks in filter media or bypass at frame — required for healthcare and cleanroom compliance
Annual filter cost (commercial AHU)£180–£650 per unit
Replacement interval (condition-based)6–18 months depending on occupancy and outdoor air quality
Frequency
Task
Why It Matters
Monthly
Log lamp operating hours from controller or hour meter
Lamp output degrades continuously — running past rated hours causes silent system failure
Quarterly
Clean lamp sleeve/quartz tube — remove dust and oil film accumulation
1mm of dust on quartz sleeve can reduce UV-C transmission by 30–50%
6–12 months
Replace lamps at 8,000–9,000 hour mark (or per manufacturer spec)
Mercury lamp output drops 15–20% from new by 8,000 hours — still appears to glow but germicidal output is inadequate
At replacement
UV-C intensity measurement with calibrated radiometer at design distance
Verifies new lamp is delivering design dose — required for healthcare accreditation
Annual
Inspect lamp mounting, ballast, wiring, and interlock safety systems
UV-C above 40mW/cm² causes permanent eye and skin damage — safety interlocks are life safety systems
Annual lamp replacement cost (per AHU)£120–£380 per unit
Replacement interval8,000–9,000 operating hours (approx. 12–14 months continuous)
HEPA and UV-C PM Schedules — Built and Tracked Automatically
OxMaint's Preventive Maintenance module schedules HEPA filter changes at differential pressure threshold, tracks UV-C lamp hours against rated life, and auto-generates work orders before systems degrade past effective performance.
When to Use HEPA, When to Use UV-C, and When to Use Both
The right deployment depends on the primary IAQ threat, the building type, the existing HVAC system, and the budget. The decision framework below covers the eight most common commercial building scenarios and the recommended purification strategy for each — based on published ASHRAE guidance, WELL certification requirements, and current best practice from facilities deploying these systems at scale. Sign up free to track your purification assets by building zone in OxMaint.
Building / Space Type
Primary IAQ Threat
Recommended Technology
Key Rationale
Commercial Office
CO₂, PM2.5, airborne virus
HEPA + UV-C
HEPA for PM2.5 and allergens; UV-C for viral inactivation and coil hygiene in multi-tenant AHUs
Healthcare Facility
Airborne pathogens, HAI prevention
HEPA + UV-C
HEPA mandatory for particle removal in clinical areas; UV-C for HVAC duct sterilisation and surface decontamination
School / University
Viral transmission, PM2.5
HEPA + UV-C
Post-pandemic evidence strongly supports combined deployment for reducing respiratory illness absenteeism in high-density occupancy
Hotel / Hospitality
Mould, legionella, guest IAQ
UV-C Priority
UV-C coil irradiation addresses mould and bacteria at the source (AHU coil and drain pan) — most cost-effective entry point for hotel HVAC IAQ
Food Manufacturing
Biological contamination, particulates
HEPA + UV-C
Food safety regulations require demonstrable pathogen control; combined deployment supports HACCP and BRC audit requirements
Data Centre
Particulate contamination of hardware
HEPA Priority
Primary threat is particle contamination causing equipment failure — HEPA filtration to ISO 14644 Class 8 standard is the primary protection
Retail / Public Space
Viral aerosols, PM2.5 from footfall
UV-C Priority
Upper-room UVGI systems or in-duct UV-C are most practical in high-footfall retail where HEPA integration into existing systems is complex
Laboratory / Cleanroom
Contamination control, particulate
HEPA Priority
ISO classification requirements mandate HEPA at rated efficiency with regular integrity testing — UV-C added where biological decontamination required
HEPA and UV-C Asset Management — One Platform, Every PM Task
OxMaint logs every HEPA filter unit and UV-C lamp in your building as a tracked asset — with PM schedules, hour meters, differential pressure thresholds, and replacement history stored automatically. Compliance evidence ready on demand for WELL, LEED, and healthcare accreditation.
Frequently Asked Questions: HEPA vs UV-C Air Purification
Can UV-C be used as a substitute for HEPA filtration in HVAC systems?
No — they target different threats entirely. UV-C inactivates biological organisms but removes zero particles; HEPA removes particles but doesn't kill anything. Comprehensive IAQ requires both in sequence: HEPA upstream, UV-C downstream or on the coil.
Sign up free to log both asset types in OxMaint.
How do I know if my UV-C lamps are still working effectively?
Visual inspection isn't enough — a glowing lamp may be delivering only 20% of its original germicidal output. Track operating hours against rated lamp life (8,000–9,000 hours for mercury lamps) and replace before that threshold. OxMaint auto-generates a replacement work order when the rated limit approaches.
Book a demo to see UV-C lamp hour tracking in action.
What is coil irradiation and is it worth the investment?
Coil irradiation installs UV-C lamps facing the evaporator coil and drain pan — continuously preventing biofilm, mould, and bacteria growth at the source. It is the single most cost-effective UV-C application in commercial HVAC, with typical payback of 2–4 years in energy and maintenance savings.
Sign up free to schedule coil irradiation PM in OxMaint.
Can existing HVAC systems be retrofitted with HEPA or UV-C without major modification?
UV-C retrofits are generally straightforward — lamps mount into existing duct sections or AHU coil compartments with minimal structural work. HEPA retrofits require verifying that the AHU fan system can handle the higher static pressure; where it can't, MERV-13 combined with UV-C delivers 70–80% of the benefit at lower cost.
Book a demo to see how OxMaint supports retrofit asset documentation.
How does OxMaint support HEPA and UV-C maintenance compliance?
OxMaint registers each filter bank and UV-C lamp as a tracked asset with its own PM schedule — differential pressure checkpoints, lamp hour logs, sleeve cleaning tasks, and annual integrity testing — all timestamped and photo-documented. The result is audit-ready compliance evidence for WELL, LEED, and healthcare accreditation without spreadsheets or paper logs.
Sign up free to get started, or
book a demo to see the full PM workflow.
