INDOOR AIR QUALITY
Viral particles are small enough to pass through traditional high efficiency HEPA and Minimum Efficiency Reporting Value (MERV) filters as the Sars-CoV-2 are between 80Nm and 160Nm (on average 0.1 microns), but they can be targeted by air purifying devices. There are a number of UV products on the market ranging from wall mounted disinfecting devices and germicidal lamps to sanitising UV wands and UV duct cleaners. But for larger projects, HVAC manufacturers have recognised the need for HVAC systems that combines comfort and sanitised air and not just for hospital environments but any building. Fan coils are widely used in HVAC systems and have been re-designed to provide an effective solution that address hygiene concerns by sanitising the indoor air, helping to make workplace safer. The units can be two or four- pipe configuration and are suitable for retrofits depending on the spatial limitations. The units operate by relying on the sanitising action of a photocatalytic system which has been proven to make legionella, fungi, mould and other virus bacteria such as flu’ and SARS inactive. Units incorporate an Ultra Violet C (UVC)
germicidal lamp with a Titanium Dioxide (TiO2) surface. When radiated by the lamp, any pollutants in the air flow are broken down into harmless substances by the free radicals created by the UVC and the TiO2 surface. The UVC lamp is shielded, so the device is harmless and has no effect on people in the room.
Titanium Dioxide (TiO2) possesses a high degree of thermal and chemical stability. It is not toxic for humans and is widely available, bio- compatible and highly sensitive to UV light. The catalyst which resembles a honeycomb, increases the photocatalysis reaction surface, which maximises and guarantees system efficiency. The interaction of the catalyst with the UV light (photocatalysis) creates an effect that attacks, breaks down and eliminates the polluting agents. These sanitising fan coil units are being used in hospitals as well as commercial premises and offer a solution for many more indoor environments including nursing homes, laboratories, dental practices, pharmaceutical companies and any other building requiring guaranteed hygienic air flows. When it comes to Covid-19 there are many questions unanswered, how the virus spreads and the role that HVAC systems can play. Although
there have been no reports to date of virus transmissions through HVAC systems, health estate managers can help minimise the spread through the cleaning of air by using a UVC light and photocatalytic oxidation equipment which can inactivate and reduce the amounts of microbiological contaminants.
How large is the UV market? Almost all commercial air conditioning systems are candidates for UV technology because of the benefits they can offer: Improved indoor air quality Destruction of airborne micro-organisms Preservation of system capacity Reduced maintenance costs
The pandemic is creating new opportunities for the HVAC industry to design systems that can provide safer environments. HVAC contractors and designers could use UV as leverage – no-one would operate an air conditioning system without a filter, dirt and other detritus would clog up the coils in no time reducing their effectiveness. Maybe the landscape is changing and the time may come when HVAC systems will only be operated with UV for the same reasons?
www.acr-news.com
November 2020 15
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