UV-C and HVAC coils
Field research on what fouled cooling coils cost, and what changes when they are cleaned or irradiated with UV-C.
Field measurement and modeling of UVC cooling coil irradiation for HVAC energy use reduction (ASHRAE RP-1738), Parts 1 and 2
Firrantello, Bahnfleth et al. · Science and Technology for the Built Environment 24(6) · 2018
ASHRAE-funded research that installed UV-C on visibly fouled cooling coils in operating air handlers in Tampa, Florida, and University Park, Pennsylvania. Part 1 reports measured changes in airside pressure drop and heat-transfer coefficient; the abstract reports lasting improvements in both at the Tampa site, while the second site, whose coil was cleaned before testing, behaved differently. Part 2 models energy use, indoor air quality and life-cycle cost against mechanical coil cleaning.
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Study verifies coil cleaning saves energy
Montgomery & Baker · ASHRAE Journal 48(11) · 2006
A case study of two air handlers serving a New York City office tower, measuring coil pressure drop and heat transfer before and after mechanical coil cleaning. It is widely cited as early field evidence that coil condition affects HVAC energy use. It studies cleaning, not UV-C.
Designing UV-C systems
The engineering behind sizing and placing UV-C: dose, reflectivity, airflow and how to test a product.
UVGI design basics for air and surface disinfection
Kowalski & Bahnfleth · HPAC Engineering 72(1) · 2000
Covers the factors that set UVGI design parameters and practical methods for sizing air and surface systems.
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Dimensional analysis of UVGI air disinfection systems
Kowalski, Bahnfleth & Rosenberger · HVAC&R Research 9(3) · 2003
Simulates thousands of in-duct configurations to identify what drives performance: dose, duct reflectivity, duct geometry, lamp shape and lamp location.
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Design and optimization of UVGI air disinfection systems
Kowalski · Doctoral thesis, Pennsylvania State University · 2001
Develops models of how microbial populations respond to UV-C and of lamp intensity fields, and uses them to predict the performance of air disinfection systems.
Guideline for design and installation of UVGI in-duct air disinfection systems (IUVA-G03A-2005)
International Ultraviolet Association · 2005
A voluntary consensus guideline from academia and industry on designing and installing in-duct UVGI.
Guidelines for quantification of airborne pathogen inactivation by UVGI technologies
Global Lighting Association · 2022, updated 2023
A test-chamber method for quantifying how well a UVGI product inactivates airborne microorganisms, so that product performance can be compared on the same basis.
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Biofilm
Why biofilm is harder to treat than free-floating microorganisms, and how UV-C research is studying it.
Control of biofilms with UV light: a critical review of methodologies, research gaps, and future directions
Gora et al. · Environmental Science: Water Research & Technology 10(12) · 2024
Reviews 58 studies published from 1998 to 2024 on UV and biofilm across water, healthcare and food safety. It finds that methods vary widely and recommends minimum reporting standards so results can be compared.
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UV-C side-emitting optical fibers for planktonic and biofilm bacteria control
Nanotechnology-Enabled Water Treatment (NEWT) Engineering Research Center
Researchers developed optical fibers that emit germicidal UV-C along their length, to reach biofilm inside narrow tubing and on membrane surfaces that lamps can’t reach.
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UV-C LED irradiation for the inactivation of biofilm-bound Pseudomonas aeruginosa bacteria
UV Solutions · 2019
Describes a bench-scale method for testing UV-C LED treatment of Pseudomonas aeruginosa biofilms with a collimated beam.
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Food contact surfaces
What UV-C does, and doesn’t do, on surfaces in food processing.
Preliminary investigation of the effect of chemical sanitizers and UV-C light on Listeria monocytogenes biofilm survivability
Mendez, Tande, Vipham & Trinetta · Food Protection Trends 42(4) · 2022
Tested lactic acid, peroxyacid and quaternary ammonium sanitizers alone and with 254 nm UV-C on Listeria biofilms grown on stainless steel. The authors report that the sanitizers outperformed UV-C alone, that combining them worked better than either, and that the order of application mattered for some sanitizers.
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Sanitizers and UV-C light on Listeria monocytogenes biofilms on produce-harvesting materials
Manville, Nwadike & Trinetta · Food Protection Trends 43(5) · 2023
A follow-up study on materials used to harvest produce. The authors report that UV-C combined with a sanitizer worked best, that UV-C alone was the least effective treatment, and that the material made a significant difference.
Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices
Sharma, Singh, Pendyala, Balamurugan & Patras · Applied and Environmental Microbiology · 2024
Measured how a 279 nm UV-C LED system inactivated E. coli, Salmonella Enteritidis and Pseudomonas fragi deposited as bioaerosols on food contact surfaces, with results that varied by surface material.
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Airborne infection and indoor air
Guidance and research on airborne transmission, ventilation and upper-room UVGI.
Environmental control for tuberculosis: basic upper-room ultraviolet germicidal irradiation guidelines for healthcare settings
NIOSH · DHHS (NIOSH) Publication No. 2009-105 · 2009
Guidance for healthcare managers, designers and engineers on designing, installing and maintaining upper-room UVGI while keeping UV levels safe in the occupied part of the room.
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ASHRAE position documents on infectious aerosols
ASHRAE
ASHRAE’s positions on ventilation, filtration and air cleaning, including UVGI, as strategies to reduce airborne disease transmission in buildings.
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Ultraviolet lighting during orthopaedic surgery and the rate of infection
Ritter, Olberding & Malinzak · Journal of Bone and Joint Surgery (Am) 89(9) · 2007
A review of 5,980 joint replacements at one hospital over nineteen years, comparing operating rooms using laminar airflow with rooms using UV lighting and staff protection. The authors report a lower infection rate with UV lighting.
A paradigm shift to combat indoor respiratory infection
Morawska et al. · Science 372(6543) · 2021
Argues that indoor air should be regulated as seriously as food and water, and calls for better building ventilation and air-cleaning standards.
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Ten scientific reasons in support of airborne transmission of SARS-CoV-2
Greenhalgh, Jimenez, Prather, Tufekci, Fisman & Schooley · The Lancet 397 · 2021
Sets out ten lines of evidence that SARS-CoV-2 spreads through the air, with implications for ventilation and air cleaning indoors.
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Susceptibility of SARS-CoV-2 to UV irradiation
Heilingloh et al. · American Journal of Infection Control 48(10) · 2020
A laboratory study of 254 nm UV-C and 365 nm UV-A on SARS-CoV-2 in liquid. The authors report that UV-C inactivated the virus, while UV-A had only a minor effect.
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