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A bit of light cleaning: Barkell launch UV coil disinfecting solution

Barkell, the UK’s air handling specialists, have announced the launch of LightGuard, a UV coil cleaning solution, to aid companies concerned about the safety of occupied buildings in the wake of the Covid-19 pandemic.

As business owners consider a return to work, many are facing a “new normal”, where cleanliness, hygiene and indoor air quality are critical to minimise risk to staff and customers. Social distancing measures, additional cleaning, partitions and one-way systems are all being considered by most companies. But what about ventilation systems?

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) recently advised:

“Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.”

Recent REFCOM advice states that “dilution of contaminated air will reduce risk from that contamination, so it is recommended that any ventilation or air conditioning system that normally runs with a recirculation mode should be set up to run on full fresh air”.

Increasing ventilation rates will reduce the risk of contaminants settling on surfaces, but ramping up to full fresh air will increase energy consumption and remove the benefits of heat recovery and free cooling. What about the prevention of airborne contaminants entering occupied spaces via ventilation equipment in the first place?  Introducing better filtration (eg HEPA) is one option, but this results in high pressure drops, intrusive modifications to existing plant, a need for more powerful fans / motors (which may require noise attenuation) and will still require regular filter changes, putting engineers at potential risk.

UV disinfection systems are coming to the forefront of the battle against Covid-19. We are seeing them being deployed in airports, hospitals and personal hygiene systems…and they are also now available for ventilation systems.

So what is Ultraviolet light and why is it effective?

Light Spectrum - UV Cleaning

Light is measured in wavelength with the Ultraviolet part of the spectrum measuring between 100 and 400 nanometers (nm). UV-C radiation is used for disinfection and is most effective at a wavelength of 264nm. It is invisible to the human eye and can inactivate microorganisms such as bacteria, viruses and fungi by preventing them from infecting and replicating.

What is UV-C effective against?

UV-C is effective against many types of bacteria (eg listeria, tuberculosis, MRSA, E-coli, legionella), fungi (eg yeast, mould) and viruses (adenoviruses, Influenza, Norovirus and Coronavirus). Applying UV-C to a cooling coil or internal surfaces of, say, an air handling unit, will effectively disinfect the surfaces of the equipment, removing harmful organisms before they potentially enter the airstream. HVAC disinfectant solutions which rely on UV light are proven to promote the following positive effects:

  • Reduced microbial contamination within HVAC systems by more than 90%
  • Lower respiratory illnesses among occupants by more than 40%
  • Natural solution to the problem of drug-resistant and chemical-resistant infectious diseases

UV Light - UV Coil Cleaning

How does LightGuard work?

A LightGuard UV-C coil cleaning system can be fitted in just about any new or existing air handling unit. The UV-C lamps (number depends on the size of the equipment and type of installation) are installed downstream of the cooling coil and use a photon concentrator which focuses up to 95% of the UV energy produced onto the coil. Installation is simple and the lamps are low energy, providing an all-round cost effective solution. The lamps require replacing only once a year, reducing coil maintenance as normal coil cleaning regimes are reduced.

The lamps prevent the build up of biofilm, a sticky microbial mass found on HVAC coils, drain pans, and ductwork.  It is secreted by communities of microorganisms, bacteria, moulds, and fungi that naturally gather in HVAC systems.

Biofilm, when allowed to build up, acts as an insulator, reducing the efficiency of heat exchange. It fills interstitial spaces, increasing pressure drop across an HVAC coil and it produces sulfite-reducing bacteria, causing corrosion to an HVAC system. The air passing through a contaminated HVAC system will pick up bacteria, moulds, and other infectious particles and distribute them throughout the building.

Biofilm is resistant to physical cleaning and chemical disinfectants so preventing its build-up in the first place is a real advantage. LightGuard has been proven in multiple applications to reduce this build-up and preserve system performance. The images below show two cooling coils in a common facility, 91 days after cleaning, without UV-C lamps installed (left) and with UV-C lamps installed (right).

Coil after 91 days – no UV Coil after 91 days – with UV










By the Numbers – the Cost of Dirty Coils


HVAC systems can account for up to 60% of a building’s total energy costs*


Dirty HVAC coils waste up to 25% additional energy*


Percentage of indoor air quality problems related to HVAC (absenteeism, lost productivity)**


6 out of 10 indoor spaces are hazardous to their occupants’ health due to air pollution***

*Source: ASHRAE

**Source: National Energy Management Institute

***Source: Underwriters Laboratories



A new way of living and working needs new solutions to ensure people are safe inside the built environment. At Barkell, our vision is to support the delivery of a UK built environment where air quality is recognised as imperative to productive, healthy working and living. That is why we are now offering LightGuard, a cost effective way of improving indoor air quality, optimising HVAC performance and saving energy.


LightGuard is offered in partnership with Biozone Scientific International, a US-based leader in UV solutions.