Heat Recovery Ventilators (HRV)(74)
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With the roadmap laid out for the government to guide us out of lockdown, the end of the pandemic seems as though it could be in sight. However, HVAC units remain outdated in hotels, hospitals, schools, and offices and there is a worry that COVID-19 can still spread quickly and easily through air vents, mitigating the effects of lockdowns and vaccinations. Dr. Rhys Thomas, Chief Scientific Officer at infection mitigation specialist PP-L and a frontline NHS doctor, says that the government’s neglect of using HVAC solutions to reduce transmission is a major oversight. Airborne transmission indoors By failing to follow the lead of other nations that are now recognizing the importance of ventilation in relation to the airborne nature of the virus, the UK’s approach hasn’t been as comprehensive or as forceful as it could be, with quietly introduced, piecemeal changes to regulations being too little, too late. At the moment, some governments don’t want to come out and admit that COVID-19 is an airborne hazard and that their failure to recognize it as such has led to higher infection and mortality rates and suffered even greater impacts from new variants. Research shows that 80% of the spread of the virus is through airborne transmission indoors– the inhalation of infected droplets that are moving around in the room’s air currents or ventilation systems– which a two-meter distance or the opening of the window is unlikely to combat. New quarantine hotels The UK was geared up for an influenza-like pandemic rather than an airborne one The airborne nature of COVID-19 is what has caught governments off guard and meant we are still playing catch-up while new variants are starting to appear, which was also always to be expected. In terms of preparedness, the UK was geared up for an influenza-like pandemic rather than an airborne one, such as the challenge posed by a SARS coronavirus. As with all airborne illnesses, the greatest risk of transmission is indoors and in confined spaces such as public transport, office buildings, factories, and even potentially the new quarantine hotels which are being introduced to prevent the spread of the virus. The governments ‘hands, face, space’ messaging cover the opening of windows to help with airflow, but the reality is much more complex. Latest SARS Coronavirus The risk of infection indoors is vastly higher than outside, and current advice simply isn’t enough. There’s a perception – even in hospitals – that fresh air is clean air. I’ve been shocked to see hospitals that I’ve visited assuming that simply opening a window is enough. That is simply not the case – the air needs to be disinfected by ultraviolet light for it to be clean enough to prevent the spread of coronaviruses. I saw this in practice in the first SARS pandemic in 2003, where UV was used and proved incredibly effective in South East Asian hospitals once again against the latest SARS Coronavirus that causes COVID-19. The spread of the virus around the Diamond Princess cruise ship, which hit global headlines in January 2020 when more than 700 passengers and crew tested positive for COVID-19, has become a case-in-point for the theory behind the airborne transmission. Killing airborne contaminants Part F of the Building Regulations on ventilation has been updated and is out to consultation Researchers from Harvard and the Illinois Institute of Technology developed a computer model of the cruise ship outbreak, which found that the virus spread most readily in microscopic droplets light enough to linger in the air. The research added to the pressure already being placed on the World Health Organization to recognize the airborne dangers of the virus, including an open letter signed by more than 200 experts. The key point here is that there has been some level of recognition from various government departments that the virus is airborne, and they have mitigated accordingly. Part F of the Building Regulations on ventilation has been updated and is out to consultation, and the Health and Safety Executive’s COVID-Secure Guidance for the Workplace on Ventilation has also been quietly updated in recent weeks to recommend the use of ultraviolet air filtration systems, which are proven to kill airborne contaminants. Key communication issue These UK regulations are now, at last, starting to get more aligned to other global institutions’ recommendations such at the renowned Centers for Disease Control and Prevention (CDC) who support the importance of ventilation and UV devices to significantly reduce infection risk. This is a positive step, but the key communication issue is that if the government don’t fully endorse and be more vocal about the airborne threat of COVID-19, and regulatory changes being made, then neither will the wider public. This is a huge issue because the government is already preparing for this virus to be around in some form for many years to come. With 40 million doses of vaccine set to arrive in 2022 and an overall supply line that is set to last until 2025, it’s clear that there is an acknowledgment that this will be a long fight. The SAGE scientists like Professor Chris Whitty and Sir Patrick Vallance are also referring to this virus as endemic now. Long-Term readiness The government is already building long-term readiness and diluting the risks by using different suppliers With 407 million doses of vaccine on order, the government is already building long-term readiness and diluting the risks by using different suppliers, but without the acknowledgment of the airborne risks, this can only do so much – it needs to be a joined-up, blended approach. Prevention is better than the alternative because in this case, there is unlikely to be a cure for a virus that spreads and mutates at the rate this one does. Trying to keep ahead of this virus is a dangerous game. It is incredibly adaptable and there is an awful lot of guesswork about predicting the spread and virulence of new and more easily spread strains. Ongoing lockdowns are simply not an option and are increasingly ineffective as people struggle with the monotony and isolation they bring. We need to get on the front foot and not only rely purely on medicine to help solve this crisis. Air filtration systems Engineered solutions like UV-C (also known as UVGI) and air filtration systems are needed wherever possible to help cut this virus at the knees and stop transmission in the first instance. These solutions are now being brought in by several industries and many countries around the world are specifically recommending them because they are recognizing that the guidelines in their current form aren’t doing enough. Those industries such as food manufacturing and production that rely on having people on the ground and in their factories are having to look beyond what they are advised and finding solutions that actually do work. Hospitals, schools, and hotels are the next places that need to be looking at this kind of response, especially with the government’s travel regulations meaning that potentially infected travelers are being kept in potentially inadequately ventilated spaces that could actually accelerate contagion spread to other travelers or staff. Action needs to be taken now, or we risk the further unnecessary spread of this dangerous pathogen.
The modern technological world is filled with ‘extrusions’. They are all around us, in the form of small and not-so-small cross sections. The function of an extrusion is to form seals between components of complex machinery and keep them functional. And, depending on the ‘type’ used, they can make a big difference to how a machine operates. Some of the most desirable types of extrusion — and especially for use in HVAC systems — are those made from silicone. Silicone, which is a type of rubber, has a robust set of properties. For one, silicone can withstand extreme temperatures, both high and low. Semi-Exterior environments Ranging from -60°C to temperatures exceeding 200°C. (And there are even higher grades that can be manufactured to withstand temperatures well above 200°C.) Ideal for HVAC units that work round the clock to keep large numbers of people in large buildings comfortable in summer and winter conditions. In addition to this, silicone is also one of the more resistant properties to the constant vibrations of working machinery. It can be difficult to locate the source of the problem if a tiny extrusion has dislodged. Vibration-resistant properties make silicone extrusions less likely to disengage or fall out of place, therefore minimizing the need for costly repairs. Finally, silicone is also more durable than most other materials when it comes to exterior or semi-exterior environments, such as that of rain or ultraviolet light. Protecting electrical components Silicone is useful in HVAC systems because it offers enhanced sealing and compression protections As a result of this favorability, there is already a considerable number of different types of silicone extrusions that can be found in a lot of HVAC systems. These include HVAC sealing gaskets, hatch seals and vibration isolation pads. But also silicone sponges, which act as a protective layer of thermal insulation. As well as providing thermal insulation, silicone sponges can double-up as a form of acoustic insulation, with considerable noise reduction and anti-squeal properties. Silicone enclosure gaskets protect electrical components, and environmental seals — as the name suggests — help to keep everything protected from the sometimes harsh elements of the environment outside. Silicone is useful in HVAC systems because it offers enhanced sealing and compression protections over most other materials. Closed cell structure On a material level, silicone has a ‘closed cell structure’, which helps to keep out moisture ingress, along with water and dust. The combination of a closed cell structure, along with sealing and compression benefits, makes silicone ideal for exterior seals and gaskets in and around HVAC systems. The softer grades of Silicone have an excellent memory and low stress relaxation, which in turn helps to prevent common faults with HVAC systems — usually caused by gasket failures made from other materials that soften and compress inaccurately. The low stress relaxation properties require minimal force on behalf of the engineers sealing the enclosures, while the memory-properties of the silicone allow it to conform to awkward shapes and gaps of various widths. Manufacturing HVAC systems proactively with silicone in mind can allow more design flexibility on behalf of the engineers. Inevitable rapid movements General purpose solid silicone or silicone sponge is suitable for many HVAC applications And, as mentioned above, vibration isolation pads work as dampers to protect against the inevitable rapid movements of the systems as they power along. But also to help withstand the vibrations of HVAC units on transport systems, such as buses and trains, which naturally vibrate as they run over imperfections on rail and road tracks. As it happens, general purpose solid silicone or silicone sponge is suitable for many HVAC applications, not just those discussed above. The designs of the extrusions would be different, reflective of their function, but the material would be the same. In some instances, customers may also require a flame retardant silicone — certified to UL94 specifications — in order to meet safety standards in certain situations or environments. Great temperature ranges For all its material advantages, silicone is generally more expensive than the other types of material rubber that are used to manufacture extrusions, such as ethylene propylene diene monomer (EPDM). And while other materials do of course have stand-out benefits of their own — EPDM for example is more hard-wearing than silicone — silicone is still often the extrusion ‘type’ of choice because of its ability to withstand great temperature ranges. This is very important for heating and air conditioning systems. Because some of the most common factors that cause HVAC systems to break down are as a result of seal and gasket failure, which can come about as a result of an overheating unit. Very cold environment Chances of a unit overheating can be just as likely — in fact perhaps more so — where the system has to operate in a very cold environment. With the threat of climate change etched more than ever into the public discussion, we can predict that there will be a steady increase in the amount that this material is used to make up the HVAC seals. And not just because, as temperatures continue to increase and summers get hotter and more prolonged, there will be an increased demand for them. Effective public relations It is no secret that HVAC systems can be relatively expensive to run It will become a matter of effective public relations for managers, building regulators and transport officers to make sure that the equipment they are using — and making — is ‘green’. By using the right materials that help conserve energy and increase efficiency, this will not only sit right with the general public, it should also be more economical, too. It is no secret that HVAC systems can be relatively expensive to run. Minimizing wastage, and the time spent on call outs and repairs will make a notable difference. Of course there are many other ways to also set about making air conditioning and heating units more efficient. Using seals or gaskets made from silicone is just one small piece of the puzzle. But utilizing them will almost certainly be more beneficial than you might imagine. And anything that is a step in the right direction is a welcome change.