So, does the solution lie within the facility’s HVAC systems? In most cases, no, for the simple reason that most buildings are engineered to provide general comfort and not to provide disease abatement. Education and conscious effort are key for prevention of COVID-19. The best practices regarding containment will remain with sanitation of surfaces, exercising judgement across the board, and plain common sense. The best prevention still lies with good personal hygiene, sanitation, a conscientious effort to avoid public or private gathering if sick and to a minor degree, the facility systems. The COVID-19 situation is still a developing story during this writing, so I hope some general guidelines help in establishing priorities and strategy for engineers at Hotels or Hotels turned into Hospitals or quarantine rooms/areas.
While the above helps, you still need people to operate and maintain your hotels and facilities. Digitization is the first step, not only to help in controlling contamination, but also enabling you to seek support from the best engineering resources available from outside your organization. Connect your facility for remote monitoring, controls and automation.
Let’s understand, how much the story has unfolded for this virus till date. According to the WHO (World Health Organization), “the COVID-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or sneezes etc.” Talking and breathing can also release droplets and particles. Droplets generally fall to the ground or other surfaces in about 1 m (3 ft), while particles (aka aerosols), behave more like a gas and can travel through the air for longer distances, where they can transmit to people and also settle on surfaces. The virus can be picked up by hands that touch contaminated surfaces (called fomite transmission) or be re-entrained into the air when disturbed on surfaces. However, if the droplet gets a chance to evaporate, since the base of the droplet is water, then it would become droplet nuclei that might circulate in HVAC system. How do we avoid or control this circulation into air?
Any air purifier that removes particles has
some potential to get rid of coronavirus? I’m not a doctor, but I’m not sure this
is the best prevention.
The question is, which filter is effective enough
that it will have a significant impact on how likely people are to get affected
by the airborne route?
Even HEPA filters which have been tested in
the laboratory with viruses will have some level of penetration. Not much — 2
percent. But if anything gets through, and if it’s a very virulent pathogen,
that doesn’t mean that you’re perfectly protected against infection by that
filter. Same goes for UV. There’s UV susceptibility of coronaviruses … it’s
maybe somewhat less than the net of influenza, but still susceptible. So, if
you were treating contaminated air or contaminated surfaces with UV, can expect
to reduce the concentration of coronavirus on it by some amount. In reality, it
can’t be confirmed that HEPA filers or UV lamps disinfect COVID-19.
What are those best engineering practices
Some of the best practices can be applied if not all are below
related to HVAC system to prevent or control this contamination:
1. Ventilation: One thing that reduces risk is having 100 percent outside air system and negative pressure in guest room. This can help to prevent spreading to outside corridors or common areas.
- Run 24×7 PAHU (Pre-cooled Air handling units) for thermal comfort
- Increase outdoor air ventilation by opening windows if outside air quality is good
- Disable Demand-Controlled Ventilation (DCV)
- Further open minimum outdoor/fresh air dampers, as high as 100%, thus eliminating re-circulation of air
- Negative pressure can help to prevent spreading, 100% exhaust and run FCU/AHU at lower speed/VSD controls.
2. Humidity: Increased/higher humidity may not let the droplet evaporate so fewer chances of circulating into HVAC System, this may help to prevent the droplet from drying out and floating freely in the air
3. Air filtration: Although, it CANNOT be confirmed that HEPA filers or UV lamps disinfect COVID-19, however good care should be taken to avoid contamination.
- Improve air filtration to the MERV-13 or the highest
compatible with the filter rack, and seal edges of the filter to limit
- If one doesn’t have MERV 13 or a better filter, please do not change
filters at all. Chocked filters are better to avoid small particulates,
more its chocked, better it is for particulates reduction.
- Use UV lights in return ducts if you can’t avoid
re-circulation of air.
Some addition measure to think about:
- Create an Isolation room in hotels: Use separate
HEX and AHU for such areas with separate controls and automation
- Use additional damper actuators to avoid
re-circulation of air across different areas
- Quarantine areas to be negative pressure area,
use automation and controls to create negative pascal, keep minimum 02 AC/H.
- Don’t switch off the area room’s ventilation
& exhaust even if you need to switch off air-conditioning for the hotel
during shut down. Let it run and disable the ventilation control.
- Run boilers to produce hot water on secondary
side above 50C+ to avoid infections.
Some actionable during the facility shutdown:
- Run the condenser water through the cooling tower to avoid formation of algae, molds/ fungi at least once a day for 4 hours or completely shut down the condenser system and drain the water from the cooling tower.
- Run chilled water pumps for at least 02 hours in a week to ensure no formation of algae.
- Run FCU and AHU fans at least once a day for 02 hours to create air changes.
- Keep the ventilation and exhaust/ especially toilet exhaust fans On 24×7 with minimum 02 air changes per hour.
- Keep the U-trap of AHU filled with water to avoid cross infection
- WC flush and urinals to be cleaned daily.
- Run the Boiler for hot water above 50C+ at least once in 15 days with water drain for 15 minutes for both wash basin and shower.
- Cover the bedsheets and mattress with vacuum plastic covers to avoid smells and moisture.
- Fabric and carpet to be cleaned with hot air once a week.
Remote monitoring and retro commissioning
(Air and water balancing) is required by an experienced team once you start
back in business or recommissioning the system after COVID-19.
This document is by no means
definitive or attempts to deal with all aspect of COVID-19. As the situation is
always evolving, this allows the hotel teams to adopt measures to better manage
health risks. Local Authorities and WHO directives will have to be followed
where applicable. Precautionary measures although not proven in its entirety to
eliminate COVID-19, are still better than NO measures at all.
I’m happy to connect and contribute my best
to help the engineering community. Feel free to connect for more. We are by
your side during this critical time. Stay safe and stay healthy.