1. UVGI Principles of Design & Installation
Successfully differentiate UVGI deign concepts and apply guideline principles
Tobias van Reenen

2. Contents Background Safety Application Metrology
Planning & Procurement
Design
Installation & Commissioning
Maintenance & Monitoring
Decommissioning

3. BACKGROUND
UVGI uses UV-C (deep UV) to inactivate airborne microbial organisms.

4. BACKGROUND
Multiple studies have shown that an 80% reduction in TB transmission can be achieved using Upper Room-UVGI

5. BACKGROUND Specification Design Maintenance Supply
50-100k UVGI devices installed in South Africa (actual number unknown)
A 2012 CSIR study found that less than 5% of systems were functional.
Problems were found with:
Specification
Design
Maintenance
Supply

6. BACKGROUND
In 2013, the NDoH implemented a moratorium on the procurement of upper room UVGI for SA Healthcare facilities until:
Design, Implementation and Maintenance guide (
Implementation of mandatory needs and risk assessments before procurement. (The guide)
Device Technical Standard Required (Draft SATS 1706:2016)
Simple, practical and affordable solutions required.

7. SAFETY
UV-A exposure is linked to skin maladies such as photo-aging and cancer
It penetrates the atmosphere, clouds and glass.
UV-B exposure is linked to skin maladies such as sun-burn and cancer
It penetrates the atmosphere and clouds but not glass.
UV-C (UVGI) exposure is NOT linked to severe skin maladies such as cancer but does cause severe eye irritation.
It doesn’t penetrate the atmosphere glass or plastic.

8. EYE SAFETY
The primary safety concern with UVGI is controlling eye exposure to prevent irritation (essentially arc-eyes)
Safe exposure limits depend on the specific UV-C wavelength.
Typically 6mJ/cm² per 8 hour working day for LPMV.
Areas with lower typical occupancy durations can accommodate higher exposure levels.
Areas such as passages and wards should demand different safety limits from each other

9. EYE SAFETY
DRAFT

10. EYE SAFETY
Avoid highly reflective surfaces in upper room (windows, chrome or aluminium flashing, etc)
Surface reflection of UV is not the same as for visible light. (Polished aluminium is highly reflective in UV-C)

11. APPLICATION (UR-UVGI)
The application of Upper Room UVGI should form a component of a comprehensive IPC policy and should not be seen as a substitute thereof.
Upper Room UVGI irradiates the upper room and relies on a vertical air exchange.

12. APPLICATION (UR-UVGI)
The dose received by any irradiated droplet nuclei is dependent on the exposure time. (W.s)
the ratio between the volumes of the irradiated zone and the whole room therefore greatly affects the efficacy of the system

13. MEASUREMENT & METERS (METROLOGY)
Equipment
Measurements performed using UV irradiance meters
Performance evaluated to within 0.1 µW/cm²
UV-C ( nm)
Eye safety evaluated to within 0.01µW/cm²
UV-B & UV-C ( nm)
Procure facility-dedicated UV meters as components of new installation contracts
Calibrate meters within system maintenance contracts

14. PLANNING AND PROCUREMENT
Pre-UV Questions / Gates
Is TB risk in area HIGH?
Is ventilation inadequate (WHO)?
Can high risk activity not be relocated?
Upgrade/Retrofit unfeasible?
Then, and only then, consider UVGI

15. PLANNING AND PROCUREMENT
When planning/budgeting for installation, also plan for:
Maintenance and monitoring
Training
Decommissioning and
Disposal

16. PLANNING AND PROCUREMENT
Data required by designers:
Room
Occupancy level
Ventilation & mode
Room size and shape (incl height)
Surfaces / obstructions

17. PLANNING AND PROCUREMENT
Data required for procurement:
Specification of UV device
Total maintained radiant flux mW (must be lifetime deprecated)
SATS 1706 compliance (2016?)
Equivalent clean air delivery rate
Declaration of maximum 1m, 2m, and 3m deprecated µW/cm2
3 or more suppliers of basic consumables
Minimum lamp change interval (≥ 1 year)
Maintenance instructions
Safety requirements

18. DESIGN Rational Design Equivalent Clean Air Delivery Rate
THREE DESIGN ROUTES AVAILABLE:
Rational Design
Performance Modelling
Equivalent Clean Air Delivery Rate
CADRe (L/s)
Volumetric Flux Density
mW/m³

19. DESIGN
RATIONAL DESIGN
Performance modelling requires the use of tools such as CAD and CFD
Transmission reduction targets
Device Radiometric data
Ventilation and air movement data (HVAC or CFD)
Agent susceptibility data (Z values)

20. DESIGN Design using device total maintained radiant flux (mW).
VOLUMETRIC FLUX DENSITY (UVc)
Design using device total maintained radiant flux (mW).
Independently measured in integrating sphere (eg TUKS)
𝑇𝑜𝑡𝑎𝑙 𝑀𝑎𝑖𝑛𝑡𝑎𝑖𝑛𝑒𝑑 𝑅𝑎𝑑𝑖𝑎𝑛𝑡 𝐹𝑙𝑢𝑥 𝑅𝑜𝑜𝑚 𝑉𝑜𝑙𝑢𝑚𝑒 ≥20𝑚𝑊/ 𝑚 3

21. DESIGN Accounts for levels of occupancy
EQUIVALENT CLEAN AIR DELIVERY RATE (CADRe)
Accounts for levels of occupancy
Bio-Aerosol decay tested in lab (NIOH)
Equivalent Ventilation Rate → CADRe (L/s)
Applies to expected occupancy levels + WHO high risk category
High Risk ≥80 L/s per person
Can be used for testing enclosed devices

22. DESIGN – Example A Room = 43.2m³ (4mx4m) Device A = 250 mW @R4500 ea.
Volumetric Distribution (20 mW/m³)
Room = 43.2m³ (4mx4m)
Device A = 250 ea.
43.2m³x20=864 mW
864/250 ≈ 3.5 devices
→ 4 devices @ R18 000
(View from top)

23. DESIGN – Example B Room = 43.2m³ (4mx4m) Device B = 500 mW @R6125 ea.
Volumetric Distribution (20 mW/m³)
Room = 43.2m³ (4mx4m)
Device B = 500 ea.
43.2m³x20=864 mW
864/500 ≈ 1.7 devices
→2 devices @ R12 250
(View from top)

24. COST OF SYSTEM BY ROOM SIZE AND DEVICE OUTPUT (for illustration only)
DESIGN (PROCUREMENT)
COST OF SYSTEM BY ROOM SIZE AND DEVICE OUTPUT (for illustration only)
R10 /mW
R12 /mW
R18 /mW
COST

25. DESIGN Device B = 250 L/s (CADRe) 2 devices x 250 = 500 L/s
WHO requires ≥ 80 L/s per person (Ventilation)
Device B = 250 L/s (CADRe)
2 devices x 250 = 500 L/s
∴ 500/80 = 6.25
= 6 people maximum
(View from top)

26. INSTALLATION Volumetric Distribution (20 mW/m³)
Volumetric Distribution (20 µW/cm²)
Spot the mistake vs
(View from top)

27. INSTALLATION
Volumetric Distribution (20 mW/m³) vs
(View from top)

28. INSTALLATION
Volumetric Distribution (20 mW/m³) vs
(View from top)

29. INSTALLATION ELECTRICAL SWITCHING AND OPERATION
UVGI devices must be permanently wired to the building electrical system
Should be interlocked with paddle/ceiling fans
The controls of UVGI devices or systems should only be accessible to authorised persons with the delegated authority and requisite training in safety and operation.
Earth leakage required for devices that can be touched by room occupants (≈2.4m).

30. INSTALLATION CEILING FANS
Use when in doubt over vertical room air mixing (always?)
Direction doesn't affect UVGI performance
Blow down in high room volumes
Blow up to avoid drafts in winter
Interlock fan controllers with UV lights

31. INSTALLATION
CEILING FANS
(location) vs
(View from top)

32. COMMISSIONING Prior to start up – CLEANING
Prior to acceptance testing – LAMP BURN-IN
(Follow lamp manufacturer's recommendations as this can vary between brands and models)

33. COMMISSIONING (Effectiveness & Safety)
INITIAL PERFORMANCE VERIFICATION TESTING
Verify EACH device’s performance independently
Switch other devices off if necessary
Measure 1 & 2m maximum irradiance values
INITIAL SAFETY VERIFICATION TESTING
Obtain agreed acceptance criteria for room
Verify eye safety once performance tests are passed
Verify with all devices turned on

34. MAINTENANCE & MONITORING
Lamps should be inspected and cleaned periodically
Fixtures should be cleaned and inspected on the same schedule as the lamps
3 or 6 months depending on performance and environment
All UV systems should be deactivated before workers enter the upper room zone.
Maintenance staff require training in the following maintenance steps…

35. MAINTENANCE PROCEDURE
Turn off fixture and let lamps cool
Open unit to manufacturer's specs
Handle lamps with clean cotton gloves to prevent oil deposits & decreasing their efficiency
Change lamps according to fixed schedule
Change ballasts or ballasts of flickering lamps
Clean lamps with alcohol dampened cloth (NOT WATER).
Dry lamps with soft cotton cloth (lint free)
Close fixtures
Turn on the system and verify lamp operation (USE PPE)
Record inspection, cleaning and replacement in maintenance logbook

36. MONITORING: Performance
Upper Room UVGI Measurements:
Repeat 1m and 2m maximum irradiance measurements:
Compare readings to previous values and declared maintained radiant flux.
Take corrective action if required
Log results and activities

37. MONITORING: Records

38. DECOMMISSIONING
Lamps containing mercury vapour are considered as hazardous waste.
Appropriate PPE should be worn where there is a risk of breaking lamps during disposal.
gloves
safety glasses
and respiratory protection

39. Thanks & Acknowledgements:
Dr T Singh (NIOH)
Prof A Stoltz (UP)
P De Jager (CSIR)
M Poluta (CSIR)
Prof Edward A. Nardell (Brigham and Women's’ Hospital)
Dr Steve N. Rudnick (Harvard School of Public Health)
Richard L. Vincent (Mount Sinai Medical Center)
Dr Paul Jensen (US Centres for Disease Control)
Prof FW Leuschner (University of Pretoria)
DR Lindiwe Mvusi (NDoH)
documents-paper-and-articles

40. IUVA Draft Guideline IUVA-G02A-2005 International Ultraviolet Association Guideline for Design and Installation of UVGI Air Disinfection Systems in New Building Construction Copyright 2005 International Ultraviolet Association
Fundamental Factors Affecting Upper-Room Ultraviolet Germicidal Irradiation—Part II. Predicting Effectiveness
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41. The International Commission on Non-Ionizing Radiation Protection
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F.W. Leuschner. UVGI MEASUREMENTS, INSTRUMENTATION & FACILITIES PLAN. Pretoria; 2014.
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42. Mphahlele M, Dharmadhikari AS, Jensen PA, et al
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43. Tobias van Reenen (tvreenen@csir.co.za)