the newsletter of tbd consultants - Autumn/Winter 2020

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In this Edition

The New Abnormal
Clearing the Air
Healthy Home Working

Construction Management Specialists

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The New Abnormal

Uncertainty seems to the order of the day currently. In this article at how people and businesses are adapting to the constantly changing environment.


Clearing the Air


We are all being encouraged to wear face masks to prevent the spread of the novel coronavirus, and that is because the virus is known to travel through the air from one person to another. But is there a way of removing the virus from the air inside a building before it can spread too far?

There are three potential ways of getting rid of an airborne virus, namely removing it from the area and disposing of it outside, killing it, and thirdly by filtering it from the air. The first option may sound like it is simply shifting the problem from one location to another, but the virus does not survive long outside of a living host and an outdoor environment is less conducive to it than an indoor one. That is why outdoor dining was allowed at reopening restaurants before indoor dining was, and it is still safer to dine outdoors. However, to ensure that any virus gets removed quickly enough to provide a reasonable measure of protection would normally mean increasing the number of air changes. It is a fact that most of the moisture droplets carrying the virus will fall out of the air within a short distance, hence the six foot ‘social distancing’, but studies indicate that some smaller droplets can remain airborne for two or three hours, so ventilation systems would provide positive, if limited, protection. One easy way of increasing air changes is to open the windows, if possible.

One of the reasons that the virus is likely to survive for a shorter time outdoors is that it is susceptible to ultraviolet light. HVAC system may already incorporate ultraviolet (UVC) systems in them to kill off any viruses before recirculating the air, so a building owner may just want to check that the ultraviolet light is still working. For new construction and HVAC upgrades, including a requirement for such a system might be advisable because this won’t be the last pandemic and killing off viruses is normally a good thing anyway. Some portable air purifiers also incorporate ultraviolet light, but the main benefit from air purifiers is in the filtration they do, and that’s what we’ll look at next.

HVAC systems and portable air purifiers incorporate filters, but they may be designed more to trap particulate matter (e.g. dust) rather than viruses. HEPA (high-efficiency particulate air) filters are seen as the best type of filter and are used in airliners to clean the recirculated air, and they are used in laboratories and hospitals. Portable air purifiers frequently use them, and they may be incorporated in your HVAC system. HEPA filters are designed to trap 99.97% of particles that are 0.3 microns in diameter, but the coronavirus is about 0.125 microns in diameter, less than a half of the size of the particles that the filter is specifically rated for. Some of the virus samples have been identified as being as small as 0.06 microns. So, does that mean that HEPA filters are useless for stopping viruses? Not really. The virus is unlikely to be traveling through the air by itself, but in a droplet of water vapor that is likely to be around 0.5 microns in size and would get stopped easily. Plus, the filter is not like a net, where the virus can just find a suitable hole to go through. It is a dense mat of fibers that a free floating virus would have to weave its way through, avoiding fibers constantly, and electrostatic charges on the fibers would be trying to reel the virus in along the way. So, such filters can be very effective, even against viruses.

That said, the air and the viruses in it still has to travel from whoever expelled them to the HVAC vent and on to the filter, and that is likely to be beyond the six foot separation distance recommended for avoiding infection. So, filtering, killing viruses with ultraviolet light, even expelling viruses from buildings are worthwhile processes, especially since Covid-19 will not be the last pandemic to hit planet Earth. However, such technologies should not be considered to be the first line of defense, but one that can help to some degree. For instance, should you be in the unfortunate position of having to care for someone suffering from Covid-19, then having an air purifier close to their bed that could capture at least some of the airborne viruses would be an advantage, but don’t let down on any other protective measures. Wearing a mask, social distancing, washing hands, and disinfecting surfaces that might have been contaminated are all still essential.

With air purifiers and HVAC systems, the faster they can cycle the air, the more effective they will be, but they’ll also be noisier. So, getting an air purifier that can handle a larger volume of air and running it at a lower speed may be the way to go.

The filters in an air purifier or in your HVAC system will need to be changed at certain intervals, to prevent them from getting clogged. Take appropriate protective measures at those times too. Any virus that had been captured in the filter is probably long dead, but there’s other matter in there that can be noxious, and potentially damaging to your health. For instance, bacteria can survive as spores for millennia, and hopefully the time between filter changes is less than that. When changing a filter, it can be worthwhile checking to see if a higher grade filter is available as the replacement.


Healthy Home Working

Telecommuting has been talked about for decades, and some people actually tried it. Now it has been forced on us, and here we look at some aspects that help you get the most benefit out of the experience.




Design consultant: Katie Levine of Vallance, Inc.