Air Plenum ceilings using the entire ceiling as an air return is suppose to save money ,when building ? A look at the myth and dangers this construction causes

Your building a new office  addition when the contractor tells you he can save you all kinds of money by eliminating the return air ducts on the H/VAC system and use the entire ceiling  as an air plenum return  system . Really?
This is the last thing you want to do because you are setting your self up for many more expenses and even your personnel health  with this type of construction.
With 35+ years of working in ceilings I have seen the deadly results these ceilings can lead to.
First off when you use a ceiling as an air return it doubles and triples the cost of installing low voltage electrical wiring in this ceiling because  air is moving past the wiring it must now be either installed in steel conduit or  fire resistant Plenum wire must be used so smoke from wire if a fire would break out in building is not spread. This also means you can not use  plastic romex type wire either for 120/240 volt wiring  if the building code  would otherwise allow it . This wiring also has to be in steel piping.

So wheres the savings the answer is there is no savings it actually cost more in the long run.

Then there is the issue with dirt and filth which these ceiling attract as you can see in picture below

This is the typical plastic Egg Crate  intake which is laid into an air plenum ceiling   and as you can see look how filthy it gets and that means all the ceiling tiles above your head look just as bad and any time you have to remove those tiles for any kind of maintenance work that dust and filth gets all over the office.
Every time I work in Air Plenum Ceilings I have to put on filter masks and still end up getting sick  as well as workers around me do to the build up in these ceilings which leads to sick building syndrome which sends hundreds of thousands of workers home sick every year .
Then if your roof leaks and it gets into these dirty ceiling tiles it can lad to deadly black mold forming . Walk into any office building with these air plenum ceilings vs regular ceiling with duct work and see for your self the air quality. If your in there all day working then you know why so many office workers get sick in the winter time.
If there going to do these type of ceiling they need to design these egg crates with filters in them that can be easily changed to keep all the dust and filth in the filter instead of up in the ceiling .
But until they decide to do this sick employees will be the norm .
No one wants to address this issue  and even admit these ceilings are such a problem but those of us who have to work in them know better.