HVAC Cabin Systems

[sabrefan]

Right now I am booked for a cruise on the Crown Princess in August 2021. I am curious to know if Princess is doing anything in terms of updating their HVAC systems and filtration on their fleet. I believe the Crown is about 15 years old and it would be nice to know if their system is updated even if their is a Covid vaccine by then.

[HUNKY]

Since the Diamond Princess HVAC systems have not been updated, although sanitized and disinfected, it is unlikely the Crown has had any HVAC upgrades.  It would be in Princess Cruises best interest to release any information regarding any completed upgrades.

[chengkp75]

While upgrading filters will provide "cleaner" air, there is to date no data to suggest that viruses like covid can travel through an HVAC system and return to a space in a viable form.  There have been no tests to see if there is a significant virus load at the filter inlet, so without knowing what needs to be removed, there is no way of knowing if an upgraded filter is doing much of anything besides costing money and looking good for PR.

 

To date, all studies of covid transmission with regards to HVAC systems deals with airflow within a space causing aerosolized virus to travel further than droplets can carry, so ideally even more distancing is needed.  The other area brought up is recirculation, but not because the recirculated air can return viruses from one space to another.  Rather, the problem is that with a typical HVAC system, only 20% of the air volume is exchanged (20% out to the outside, 20% fresh air in from outside) every minute, and so the air in the space (potentially carrying aerosolized virus) remains in the space longer than if you have 100% air exchange.  Now, ship cabins recirculate air, but only within that cabin, and public spaces recirculate air to the space, but since the doors are generally open, there can be co-mingling of air from various spaces.  But, even if a ship goes to "no recirculation", that does not mean it will have a 100% per minute air exchange rate, without having to change fans and rip out ducting to increase duct sizes.  And, even with 100% air exchange, the airflow through the space (from the supply registers to the exhaust registers) would be so great that it would encourage aerosol transmission even more.  A final problem is that going to 100% air exchange would require a more than 4 fold increase in cooling energy required, and that would require nearly every ship to add additional chillers, for which there likely isn't any room in the engine room for.